Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


solder mask

Jacqueline Coia

#10237

solder mask | 9 August, 1999

I am having cleaning problems when processing PCB's which have TAIYO solder mask on them. After processing, hand soldering and cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? Thanks in advance.

reply »

JohnW

#10238

Re: solder mask | 9 August, 1999

| I am having cleaning problems when processing PCB's which have | TAIYO solder mask on them. After processing, hand soldering and | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | Thanks in advance. | Jacqueline,

I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed.

JohnW

reply »

Earl Moon

#10239

Re: solder mask | 9 August, 1999

| | I am having cleaning problems when processing PCB's which have | | TAIYO solder mask on them. After processing, hand soldering and | | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | | Thanks in advance. | | | Jacqueline, | | I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. | What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. | Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed. | | JohnW | Folks,

All photoimageable soldermasks are epoxy/resin based. They must properly be applied and cured. This means, as they are epoxies/resins of some form (polymers) they must adhere through polymerization or cross linking molecular structures - both with themselves and the surface upon which they must adhere. Process management, when failures occur, is the key to defect prevention. If they're not properly administered and applied, they will do wierd things - as in being sticky.

Earl Moon

reply »

Brian

#10240

Re: solder mask | 10 August, 1999

| | | I am having cleaning problems when processing PCB's which have | | | TAIYO solder mask on them. After processing, hand soldering and | | | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | | | Thanks in advance. | | | | | Jacqueline, | | | | I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. | | What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. | | Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed. | | | | JohnW | | | Folks, | | All photoimageable soldermasks are epoxy/resin based. They must properly be applied and cured. This means, as they are epoxies/resins of some form (polymers) they must adhere through polymerization or cross linking molecular structures - both with themselves and the surface upon which they must adhere. Process management, when failures occur, is the key to defect prevention. If they're not properly administered and applied, they will do wierd things - as in being sticky. | | Earl Moon | I agree with the others: this sounds like a fab problem. I don't know your particular mask but photoimageable resists generally work on a pre-polymerisation due to partial cross-linking of the epoxy by means of an e.g. cinnamate-activated acrylic molecule, leaving free radicals in the structure. This pre-polymerisation is hard enough to allow the developer to dissolve or wash away the unexposed stuff and not the exposed stuff. After development, the polymerisation must be completed, usually thermally, allowing the free radicals to do their stuff in completing (hopefully) the cross-linking. It sounds as if your board vendor may have forgotten the post-development polymerisation bake. :-(

Easy goods-in polymerisation check: clean, white, cotton cloth: wrap it round a suitably gloved finger and pour a few drops of methylene chloride (! toxic) onto the end of the finger and rub it onto the bare board for a minute or so. If it comes away coloured, reject the boards. (These simple tests are often forgotten in this day and age of sophisticated instrumentation, but we old-timers were brought up on them!)

Hope this helps.

Brian

reply »

Earl Moon

#10241

Re: solder mask | 10 August, 1999

| | | | I am having cleaning problems when processing PCB's which have | | | | TAIYO solder mask on them. After processing, hand soldering and | | | | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | | | | Thanks in advance. | | | | | | | Jacqueline, | | | | | | I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. | | | What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. | | | Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed. | | | | | | JohnW | | | | | Folks, | | | | All photoimageable soldermasks are epoxy/resin based. They must properly be applied and cured. This means, as they are epoxies/resins of some form (polymers) they must adhere through polymerization or cross linking molecular structures - both with themselves and the surface upon which they must adhere. Process management, when failures occur, is the key to defect prevention. If they're not properly administered and applied, they will do wierd things - as in being sticky. | | | | Earl Moon | | | I agree with the others: this sounds like a fab problem. I don't know your particular mask but photoimageable resists generally work on a pre-polymerisation due to partial cross-linking of the epoxy by means of an e.g. cinnamate-activated acrylic molecule, leaving free radicals in the structure. This pre-polymerisation is hard enough to allow the developer to dissolve or wash away the unexposed stuff and not the exposed stuff. After development, the polymerisation must be completed, usually thermally, allowing the free radicals to do their stuff in completing (hopefully) the cross-linking. It sounds as if your board vendor may have forgotten the post-development polymerisation bake. :-( | | Easy goods-in polymerisation check: clean, white, cotton cloth: wrap it round a suitably gloved finger and pour a few drops of methylene chloride (! toxic) onto the end of the finger and rub it onto the bare board for a minute or so. If it comes away coloured, reject the boards. (These simple tests are often forgotten in this day and age of sophisticated instrumentation, but we old-timers were brought up on them!) | | Hope this helps. | | Brian | Ah, the days of methelyne chloride and WHAT? No wonder I can't rember all I forgot. Don't you forget, boys and girls, the stuff is available in some paint and/or hardware stores. It also is an ingredient in some paints and my brain - but Brian is right. It will tell the tail/tale - damn I forgot again.

Moonman

reply »

#10242

Re: solder mask | 10 August, 1999

| | | | | I am having cleaning problems when processing PCB's which have | | | | | TAIYO solder mask on them. After processing, hand soldering and | | | | | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | | | | | Thanks in advance. | | | | | | | | | Jacqueline, | | | | | | | | I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. | | | | What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. | | | | Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed. | | | | | | | | JohnW | | | | | | | Folks, | | | | | | All photoimageable soldermasks are epoxy/resin based. They must properly be applied and cured. This means, as they are epoxies/resins of some form (polymers) they must adhere through polymerization or cross linking molecular structures - both with themselves and the surface upon which they must adhere. Process management, when failures occur, is the key to defect prevention. If they're not properly administered and applied, they will do wierd things - as in being sticky. | | | | | | Earl Moon | | | | | I agree with the others: this sounds like a fab problem. I don't know your particular mask but photoimageable resists generally work on a pre-polymerisation due to partial cross-linking of the epoxy by means of an e.g. cinnamate-activated acrylic molecule, leaving free radicals in the structure. This pre-polymerisation is hard enough to allow the developer to dissolve or wash away the unexposed stuff and not the exposed stuff. After development, the polymerisation must be completed, usually thermally, allowing the free radicals to do their stuff in completing (hopefully) the cross-linking. It sounds as if your board vendor may have forgotten the post-development polymerisation bake. :-( | | | | Easy goods-in polymerisation check: clean, white, cotton cloth: wrap it round a suitably gloved finger and pour a few drops of methylene chloride (! toxic) onto the end of the finger and rub it onto the bare board for a minute or so. If it comes away coloured, reject the boards. (These simple tests are often forgotten in this day and age of sophisticated instrumentation, but we old-timers were brought up on them!) | | | | Hope this helps. | | | | Brian | | | Ah, the days of methelyne chloride and WHAT? No wonder I can't rember all I forgot. Don't you forget, boys and girls, the stuff is available in some paint and/or hardware stores. It also is an ingredient in some paints and my brain - but Brian is right. It will tell the tail/tale - damn I forgot again. | | Moonman

It's also a major part of many of the more aggressive aerosol spray flux removers and, if i'm not forgetting, many paint removers. John Thorup

reply »

Earl Moon

#10243

Re: solder mask | 10 August, 1999

| | | | | | I am having cleaning problems when processing PCB's which have | | | | | | TAIYO solder mask on them. After processing, hand soldering and | | | | | | cleaning, a sticky residue is remains, resulting in a cosmetically poor finish with tide marks etc. Other soldermasks do not show the same problems after similar processing. Is there any known inherent problems when using TAIYO? Or could this relate to an incidence during PCB manufacturing process? | | | | | | Thanks in advance. | | | | | | | | | | | Jacqueline, | | | | | | | | | | I run a number of board's with Taiyo resist and have had no problems at all so I don't think it's something inherent in the actual mask but you may be pointing in the right area when you ask about the PCB fab process, there is the posibility the mask isn't cured right and it's this that's causing the problems. | | | | | What would be helpful is to know what waterwash paste your using and what the process is e.g. SMd tops, SMD Botoms, wash , wavesolder..and so on. It may be a paste flux or pure flux compatibility issue with the mask. | | | | | Of course it could also be the waterwash and what ever chemical's are in there so I guess more info is needed. | | | | | | | | | | JohnW | | | | | | | | | Folks, | | | | | | | | All photoimageable soldermasks are epoxy/resin based. They must properly be applied and cured. This means, as they are epoxies/resins of some form (polymers) they must adhere through polymerization or cross linking molecular structures - both with themselves and the surface upon which they must adhere. Process management, when failures occur, is the key to defect prevention. If they're not properly administered and applied, they will do wierd things - as in being sticky. | | | | | | | | Earl Moon | | | | | | | I agree with the others: this sounds like a fab problem. I don't know your particular mask but photoimageable resists generally work on a pre-polymerisation due to partial cross-linking of the epoxy by means of an e.g. cinnamate-activated acrylic molecule, leaving free radicals in the structure. This pre-polymerisation is hard enough to allow the developer to dissolve or wash away the unexposed stuff and not the exposed stuff. After development, the polymerisation must be completed, usually thermally, allowing the free radicals to do their stuff in completing (hopefully) the cross-linking. It sounds as if your board vendor may have forgotten the post-development polymerisation bake. :-( | | | | | | Easy goods-in polymerisation check: clean, white, cotton cloth: wrap it round a suitably gloved finger and pour a few drops of methylene chloride (! toxic) onto the end of the finger and rub it onto the bare board for a minute or so. If it comes away coloured, reject the boards. (These simple tests are often forgotten in this day and age of sophisticated instrumentation, but we old-timers were brought up on them!) | | | | | | Hope this helps. | | | | | | Brian | | | | | Ah, the days of methelyne chloride and WHAT? No wonder I can't rember all I forgot. Don't you forget, boys and girls, the stuff is available in some paint and/or hardware stores. It also is an ingredient in some paints and my brain - but Brian is right. It will tell the tail/tale - damn I forgot again. | | | | Moonman | | It's also a major part of many of the more aggressive aerosol | spray flux removers and, if i'm not forgetting, many paint removers. | John Thorup | John,

As I light up a Bud, I see you. How can we forget this. Again, no matter, the stuff will tell epoxy resin cure. So will process control - done up front.

See you man,

MoonMan

reply »

Brian

#10244

Re: solder mask | 11 August, 1999

| | | Easy goods-in polymerisation check: clean, white, cotton cloth: wrap it round a suitably gloved finger and pour a few drops of methylene chloride (! toxic) onto the end of the finger and rub it onto the bare board for a minute or so. If it comes away coloured, reject the boards. (These simple tests are often forgotten in this day and age of sophisticated instrumentation, but we old-timers were brought up on them!) | | | | | | Hope this helps. | | | | | | Brian | | | | | Ah, the days of methelyne chloride and WHAT? No wonder I can't rember all I forgot. Don't you forget, boys and girls, the stuff is available in some paint and/or hardware stores. It also is an ingredient in some paints and my brain - but Brian is right. It will tell the tail/tale - damn I forgot again. | | | | Moonman | | It's also a major part of many of the more aggressive aerosol | spray flux removers and, if i'm not forgetting, many paint removers. | John Thorup | John

You're quite right. However, anyone who uses MeCl in an aerosol spray needs his head examining. I'll go further: if he continues, he will most CERTAINLY need his head, the rest of his CNS and his liver examining a little later on. It has not been proven as carcinogenic but, boy, is it toxic or is it toxic? Some countries put the OEL/PEL as low as 10 ppm, although most are around the 50 ppm mark. After all, MeCl (a.k.a. dichloromethane) is not far removed from carbon tet (a.k.a. tetrachloromethane), and would you spray that stuff for a hobby? Used outdoors as an occasional brush-on paint stripper is fairly safe, at least for the operator, or used occasionally as I described is reasonable provided the operator is not doing such testing 8+h/day with his nose glued to the job.

Quite apart from the H&S aspect, it is not clever to emit ANY excessive chlorocarbons into the atmosphere and spraying is one helluva way of doing just this. The environmental effects are not brilliant, although MeCl is not the worst, by far. It has a very low ozone-depleting potential in mid-latitudes but may have a higher ODP at low latitudes (research is currently under way about the mechanisms whereby low lifetime halocarbons reach the ozone layer). It is not significantly global warming, because it has a poor atmospheric stability, but it and some of its decomposition products are VOCs and precursors of some leguminous crop yield-reducers. Again, the litre bottle to wet the cotton rag in a goods-in department is not going to make any difference, because it will last 2 years, but a 500 g aerosol can or so per day is a horse of another colour.

I enjoin all NEVER to use an aerosol spray (or other type of spray, for that matter) which contains any chlorinated, brominated or fluorinated solvent. (... please???...) for environmental reasons (all of them) or H&S reasons (all of them except possibly those with HFCs, HFEs or PFCs).

Wow! That's got that off my chest! Sorry for the sermon, but you may guess I feel a little strongly about the subject, having worked with solvents since before many of you were even a gleam in your father's eye and having worked to moderate their use to the strict necessary with many international and national government agencies and NGOs for decades.

Best regards

Brian

PS I have a page on chlorocarbon solvents on our web site (also pp on bromo- and fluoro-carbon ones) under environment|air for further entertainment.

reply »

#10245

Re: solder mask | 11 August, 1999

(snip) | | You're quite right. However, anyone who uses MeCl in an aerosol spray needs his head examining. I'll go further: if he continues, he will most CERTAINLY need his head, the rest of his CNS and his liver examining a little later on. It has not been proven as carcinogenic but, boy, is it toxic or is it toxic? Some countries put the OEL/PEL as low as 10 ppm, although most are around the 50 ppm mark. After all, MeCl (a.k.a. dichloromethane) is not far removed from carbon tet (a.k.a. tetrachloromethane), and would you spray that stuff for a hobby? Used outdoors as an occasional brush-on paint stripper is fairly safe, at least for the operator, or used occasionally as I described is reasonable provided the operator is not doing such testing 8+h/day with his nose glued to the job. | | Quite apart from the H&S aspect, it is not clever to emit ANY excessive chlorocarbons into the atmosphere and spraying is one helluva way of doing just this. The environmental effects are not brilliant, although MeCl is not the worst, by far. It has a very low ozone-depleting potential in mid-latitudes but may have a higher ODP at low latitudes (research is currently under way about the mechanisms whereby low lifetime halocarbons reach the ozone layer). It is not significantly global warming, because it has a poor atmospheric stability, but it and some of its decomposition products are VOCs and precursors of some leguminous crop yield-reducers. Again, the litre bottle to wet the cotton rag in a goods-in department is not going to make any difference, because it will last 2 years, but a 500 g aerosol can or so per day is a horse of another colour. | | I enjoin all NEVER to use an aerosol spray (or other type of spray, for that matter) which contains any chlorinated, brominated or fluorinated solvent. (... please???...) for environmental reasons (all of them) or H&S reasons (all of them except possibly those with HFCs, HFEs or PFCs). | | Wow! That's got that off my chest! Sorry for the sermon, but you may guess I feel a little strongly about the subject, having worked with solvents since before many of you were even a gleam in your father's eye and having worked to moderate their use to the strict necessary with many international and national government agencies and NGOs for decades. | | Best regards | | Brian | | PS I have a page on chlorocarbon solvents on our web site (also pp on bromo- and fluoro-carbon ones) under environment|air for further entertainment. | | Hey Brian, that's a bunch of bad, voodo science. The ozone hole has increased in size since the Montreal Protocol was implemented!!!! See the link. My2�. Dave F

reply »

Brian

#10246

Re: solder mask | 12 August, 1999

| | (snip) | | | | You're quite right. However, anyone who uses MeCl in an aerosol spray needs his head examining. I'll go further: if he continues, he will most CERTAINLY need his head, the rest of his CNS and his liver examining a little later on. It has not been proven as carcinogenic but, boy, is it toxic or is it toxic? Some countries put the OEL/PEL as low as 10 ppm, although most are around the 50 ppm mark. After all, MeCl (a.k.a. dichloromethane) is not far removed from carbon tet (a.k.a. tetrachloromethane), and would you spray that stuff for a hobby? Used outdoors as an occasional brush-on paint stripper is fairly safe, at least for the operator, or used occasionally as I described is reasonable provided the operator is not doing such testing 8+h/day with his nose glued to the job. | | | | Quite apart from the H&S aspect, it is not clever to emit ANY excessive chlorocarbons into the atmosphere and spraying is one helluva way of doing just this. The environmental effects are not brilliant, although MeCl is not the worst, by far. It has a very low ozone-depleting potential in mid-latitudes but may have a higher ODP at low latitudes (research is currently under way about the mechanisms whereby low lifetime halocarbons reach the ozone layer). It is not significantly global warming, because it has a poor atmospheric stability, but it and some of its decomposition products are VOCs and precursors of some leguminous crop yield-reducers. Again, the litre bottle to wet the cotton rag in a goods-in department is not going to make any difference, because it will last 2 years, but a 500 g aerosol can or so per day is a horse of another colour. | | | | I enjoin all NEVER to use an aerosol spray (or other type of spray, for that matter) which contains any chlorinated, brominated or fluorinated solvent. (... please???...) for environmental reasons (all of them) or H&S reasons (all of them except possibly those with HFCs, HFEs or PFCs). | | | | Wow! That's got that off my chest! Sorry for the sermon, but you may guess I feel a little strongly about the subject, having worked with solvents since before many of you were even a gleam in your father's eye and having worked to moderate their use to the strict necessary with many international and national government agencies and NGOs for decades. | | | | Best regards | | | | Brian | | | | PS I have a page on chlorocarbon solvents on our web site (also pp on bromo- and fluoro-carbon ones) under environment|air for further entertainment. | | | | | Hey Brian, that's a bunch of bad, voodo science. The ozone hole has increased in size since the Montreal Protocol was implemented!!!! See the link. My2�. Dave F | Whoa, Dave, them's fighting words.

I've been very heavily involved in this subject for many, many years. Among my qualifications, I'm a founder member of and Swiss Government delegate to the Montreal Protocol Solvents Technical Options Committee and I chair the Electronics Working Group, so please excuse me if I pull rank and say that I do know what I'm talking about. Sorry about starting with the heavy hand.

An explanation of why ozone depletion is still increasing is in order. You are quite right that this is so and it will continue to do so for another 20-30 years, yet. However, as you can see from your chart, the RATE of increase is beginning to show signs of slowing down, thanks to the measures already taken. If you really want to know more, the Scientific Assessment Panel of the Montreal Protocol has published a 1998 Report (2 50 mm thick A4 volumes) which I'll forebear from reproducing here :-)

Briefly, most ozone-depleting substances, including carbon tet, CFC refrigerants, propellants, foam blowers, solvents, etc. Have an atmospheric lifetime (1/e) of typically 80-100 years. This means that much of the stuff we emitted 2 or more decades ago is still reaching the ozone layer and causing depletion. Halons (fire extinguishers) are worse, with a lifetime of typically 300 years. Until this "store" of OD substances diminishes, then depletion will continue. It will take at least 100 years before we see pre-CFC ozone levels in the lower stratosphere and upper troposphere. The encouraging thing is with 1,1,1-trichloroethane. This has a shorter lifetime and consequently smaller ODP but the massive quantities used means that the effect of stopping its use is much more immediate and part of the slow-down may be attributed to this. Similarly, methyl bromide, used as an agricultural fumigant, has a short lifetime and its diminishing use will have a fairly rapid effect, although 1/3 of the MeBr in the stratosphere comes from natural sources.

Recent research on new brominated solvents has revealed that short lifetime substances has a latitude-sensitive effect on their ODP. The so-called non-OD solvents, such as trichloroethylene, perchloroethylene and methylene chloride, actually are ozone-depleting, but their ODP, calculated using the old 2-D models have been classed as negligible, Trike, for example has a calculated ODP of 0.0004. It is possible that this will be increased by more than an order of magnitude greater in certain latitudes when all the current research is finished. This would still be low, but not quite as negligible as before (there is almost no risk of regulation of these substances under the Protocol). This is not the case with n-propyl bromide, currently unregulated, where the ODP may be higher than that of 1,1,1-TCA in some places. The forthcoming Meeting of the Parties to the Montreal Protocol, to take place in Beijing, has been requested to take interim measures to limit the damage due to nPB. (I won't discuss here the H&S aspects of nPB, but I can hear the litigation lawyers beginning to rub their hands in anticipation).

In summary: we can expect further increases in ozone depletion for decades.

I hope this very short diatribe will explain better what I said previously. Believe me, Dave, the science is very real and not at all voodoo. If you wish me to predict some voodoo things, let me loose on fluorinated solvents, especially PFCs.

Best regards

Brian

reply »

#10247

Re: solder mask | 12 August, 1999

| | | | (snip) | | | | | | You're quite right. However, anyone who uses MeCl in an aerosol spray needs his head examining. I'll go further: if he continues, he will most CERTAINLY need his head, the rest of his CNS and his liver examining a little later on. It has not been proven as carcinogenic but, boy, is it toxic or is it toxic? Some countries put the OEL/PEL as low as 10 ppm, although most are around the 50 ppm mark. After all, MeCl (a.k.a. dichloromethane) is not far removed from carbon tet (a.k.a. tetrachloromethane), and would you spray that stuff for a hobby? Used outdoors as an occasional brush-on paint stripper is fairly safe, at least for the operator, or used occasionally as I described is reasonable provided the operator is not doing such testing 8+h/day with his nose glued to the job. | | | | | | Quite apart from the H&S aspect, it is not clever to emit ANY excessive chlorocarbons into the atmosphere and spraying is one helluva way of doing just this. The environmental effects are not brilliant, although MeCl is not the worst, by far. It has a very low ozone-depleting potential in mid-latitudes but may have a higher ODP at low latitudes (research is currently under way about the mechanisms whereby low lifetime halocarbons reach the ozone layer). It is not significantly global warming, because it has a poor atmospheric stability, but it and some of its decomposition products are VOCs and precursors of some leguminous crop yield-reducers. Again, the litre bottle to wet the cotton rag in a goods-in department is not going to make any difference, because it will last 2 years, but a 500 g aerosol can or so per day is a horse of another colour. | | | | | | I enjoin all NEVER to use an aerosol spray (or other type of spray, for that matter) which contains any chlorinated, brominated or fluorinated solvent. (... please???...) for environmental reasons (all of them) or H&S reasons (all of them except possibly those with HFCs, HFEs or PFCs). | | | | | | Wow! That's got that off my chest! Sorry for the sermon, but you may guess I feel a little strongly about the subject, having worked with solvents since before many of you were even a gleam in your father's eye and having worked to moderate their use to the strict necessary with many international and national government agencies and NGOs for decades. | | | | | | Best regards | | | | | | Brian | | | | | | PS I have a page on chlorocarbon solvents on our web site (also pp on bromo- and fluoro-carbon ones) under environment|air for further entertainment. | | | | | | | | Hey Brian, that's a bunch of bad, voodo science. The ozone hole has increased in size since the Montreal Protocol was implemented!!!! See the link. My2�. Dave F | | | Whoa, Dave, them's fighting words. | | I've been very heavily involved in this subject for many, many years. Among my qualifications, I'm a founder member of and Swiss Government delegate to the Montreal Protocol Solvents Technical Options Committee and I chair the Electronics Working Group, so please excuse me if I pull rank and say that I do know what I'm talking about. Sorry about starting with the heavy hand. | | An explanation of why ozone depletion is still increasing is in order. You are quite right that this is so and it will continue to do so for another 20-30 years, yet. However, as you can see from your chart, the RATE of increase is beginning to show signs of slowing down, thanks to the measures already taken. If you really want to know more, the Scientific Assessment Panel of the Montreal Protocol has published a 1998 Report (2 50 mm thick A4 volumes) which I'll forebear from reproducing here :-) | | Briefly, most ozone-depleting substances, including carbon tet, CFC refrigerants, propellants, foam blowers, solvents, etc. Have an atmospheric lifetime (1/e) of typically 80-100 years. This means that much of the stuff we emitted 2 or more decades ago is still reaching the ozone layer and causing depletion. Halons (fire extinguishers) are worse, with a lifetime of typically 300 years. Until this "store" of OD substances diminishes, then depletion will continue. It will take at least 100 years before we see pre-CFC ozone levels in the lower stratosphere and upper troposphere. The encouraging thing is with 1,1,1-trichloroethane. This has a shorter lifetime and consequently smaller ODP but the massive quantities used means that the effect of stopping its use is much more immediate and part of the slow-down may be attributed to this. Similarly, methyl bromide, used as an agricultural fumigant, has a short lifetime and its diminishing use will have a fairly rapid effect, although 1/3 of the MeBr in the stratosphere comes from natural sources. | | Recent research on new brominated solvents has revealed that short lifetime substances has a latitude-sensitive effect on their ODP. The so-called non-OD solvents, such as trichloroethylene, perchloroethylene and methylene chloride, actually are ozone-depleting, but their ODP, calculated using the old 2-D models have been classed as negligible, Trike, for example has a calculated ODP of 0.0004. It is possible that this will be increased by more than an order of magnitude greater in certain latitudes when all the current research is finished. This would still be low, but not quite as negligible as before (there is almost no risk of regulation of these substances under the Protocol). This is not the case with n-propyl bromide, currently unregulated, where the ODP may be higher than that of 1,1,1-TCA in some places. The forthcoming Meeting of the Parties to the Montreal Protocol, to take place in Beijing, has been requested to take interim measures to limit the damage due to nPB. (I won't discuss here the H&S aspects of nPB, but I can hear the litigation lawyers beginning to rub their hands in anticipation). | | In summary: we can expect further increases in ozone depletion for decades. | | I hope this very short diatribe will explain better what I said previously. Believe me, Dave, the science is very real and not at all voodoo. If you wish me to predict some voodoo things, let me loose on fluorinated solvents, especially PFCs. | | Best regards | | Brian | Yes your Generalosity!!!! No amount of "wall paper," "we�re getting results, but you can�t see them for 30 years," and cartoons of happy / unhappy children will overcome the fact that the model is a theoretical doomsday assessment with no scientific support. Deep pocketed social engineers at the UN have bulled this through. Brush-up on:

� Cyclamates. � Geologic uniformity versus plate tectonics and Velikovsky�s "Worlds In Collision."

As examples of popular, high minded theory that over a long time couldn�t hold-up to popular, high minded theory.

And they�re doing it again with this Euro-lead ban, where the most sensible explanation was: Danes incinerate everything and they don�t want to have dispose of the lead residues left over from burning boards. Gee, I wonder if there�s a connection between ozone depletion and Danes burning their trash??? I�m thinking of a nine letter word the first letter is "re" and the last letter is "cycling."

my2�

Dave F

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Boca

#10248

Re: solder mask | 13 August, 1999

| | | | | | (snip) | | | | | | | | You're quite right. However, anyone who uses MeCl in an aerosol spray needs his head examining. I'll go further: if he continues, he will most CERTAINLY need his head, the rest of his CNS and his liver examining a little later on. It has not been proven as carcinogenic but, boy, is it toxic or is it toxic? Some countries put the OEL/PEL as low as 10 ppm, although most are around the 50 ppm mark. After all, MeCl (a.k.a. dichloromethane) is not far removed from carbon tet (a.k.a. tetrachloromethane), and would you spray that stuff for a hobby? Used outdoors as an occasional brush-on paint stripper is fairly safe, at least for the operator, or used occasionally as I described is reasonable provided the operator is not doing such testing 8+h/day with his nose glued to the job. | | | | | | | | Quite apart from the H&S aspect, it is not clever to emit ANY excessive chlorocarbons into the atmosphere and spraying is one helluva way of doing just this. The environmental effects are not brilliant, although MeCl is not the worst, by far. It has a very low ozone-depleting potential in mid-latitudes but may have a higher ODP at low latitudes (research is currently under way about the mechanisms whereby low lifetime halocarbons reach the ozone layer). It is not significantly global warming, because it has a poor atmospheric stability, but it and some of its decomposition products are VOCs and precursors of some leguminous crop yield-reducers. Again, the litre bottle to wet the cotton rag in a goods-in department is not going to make any difference, because it will last 2 years, but a 500 g aerosol can or so per day is a horse of another colour. | | | | | | | | I enjoin all NEVER to use an aerosol spray (or other type of spray, for that matter) which contains any chlorinated, brominated or fluorinated solvent. (... please???...) for environmental reasons (all of them) or H&S reasons (all of them except possibly those with HFCs, HFEs or PFCs). | | | | | | | | Wow! That's got that off my chest! Sorry for the sermon, but you may guess I feel a little strongly about the subject, having worked with solvents since before many of you were even a gleam in your father's eye and having worked to moderate their use to the strict necessary with many international and national government agencies and NGOs for decades. | | | | | | | | Best regards | | | | | | | | Brian | | | | | | | | PS I have a page on chlorocarbon solvents on our web site (also pp on bromo- and fluoro-carbon ones) under environment|air for further entertainment. | | | | | | | | | | | Hey Brian, that's a bunch of bad, voodo science. The ozone hole has increased in size since the Montreal Protocol was implemented!!!! See the link. My2�. Dave F | | | | | Whoa, Dave, them's fighting words. | | | | I've been very heavily involved in this subject for many, many years. Among my qualifications, I'm a founder member of and Swiss Government delegate to the Montreal Protocol Solvents Technical Options Committee and I chair the Electronics Working Group, so please excuse me if I pull rank and say that I do know what I'm talking about. Sorry about starting with the heavy hand. | | | | An explanation of why ozone depletion is still increasing is in order. You are quite right that this is so and it will continue to do so for another 20-30 years, yet. However, as you can see from your chart, the RATE of increase is beginning to show signs of slowing down, thanks to the measures already taken. If you really want to know more, the Scientific Assessment Panel of the Montreal Protocol has published a 1998 Report (2 50 mm thick A4 volumes) which I'll forebear from reproducing here :-) | | | | Briefly, most ozone-depleting substances, including carbon tet, CFC refrigerants, propellants, foam blowers, solvents, etc. Have an atmospheric lifetime (1/e) of typically 80-100 years. This means that much of the stuff we emitted 2 or more decades ago is still reaching the ozone layer and causing depletion. Halons (fire extinguishers) are worse, with a lifetime of typically 300 years. Until this "store" of OD substances diminishes, then depletion will continue. It will take at least 100 years before we see pre-CFC ozone levels in the lower stratosphere and upper troposphere. The encouraging thing is with 1,1,1-trichloroethane. This has a shorter lifetime and consequently smaller ODP but the massive quantities used means that the effect of stopping its use is much more immediate and part of the slow-down may be attributed to this. Similarly, methyl bromide, used as an agricultural fumigant, has a short lifetime and its diminishing use will have a fairly rapid effect, although 1/3 of the MeBr in the stratosphere comes from natural sources. | | | | Recent research on new brominated solvents has revealed that short lifetime substances has a latitude-sensitive effect on their ODP. The so-called non-OD solvents, such as trichloroethylene, perchloroethylene and methylene chloride, actually are ozone-depleting, but their ODP, calculated using the old 2-D models have been classed as negligible, Trike, for example has a calculated ODP of 0.0004. It is possible that this will be increased by more than an order of magnitude greater in certain latitudes when all the current research is finished. This would still be low, but not quite as negligible as before (there is almost no risk of regulation of these substances under the Protocol). This is not the case with n-propyl bromide, currently unregulated, where the ODP may be higher than that of 1,1,1-TCA in some places. The forthcoming Meeting of the Parties to the Montreal Protocol, to take place in Beijing, has been requested to take interim measures to limit the damage due to nPB. (I won't discuss here the H&S aspects of nPB, but I can hear the litigation lawyers beginning to rub their hands in anticipation). | | | | In summary: we can expect further increases in ozone depletion for decades. | | | | I hope this very short diatribe will explain better what I said previously. Believe me, Dave, the science is very real and not at all voodoo. If you wish me to predict some voodoo things, let me loose on fluorinated solvents, especially PFCs. | | | | Best regards | | | | Brian | | | Yes your Generalosity!!!! No amount of "wall paper," "we�re getting results, but you can�t see them for 30 years," and cartoons of happy / unhappy children will overcome the fact that the model is a theoretical doomsday assessment with no scientific support. Deep pocketed social engineers at the UN have bulled this through. Brush-up on: | | � Cyclamates. | � Geologic uniformity versus plate tectonics and Velikovsky�s "Worlds In Collision." | | As examples of popular, high minded theory that over a long time couldn�t hold-up to popular, high minded theory. | | And they�re doing it again with this Euro-lead ban, where the most sensible explanation was: Danes incinerate everything and they don�t want to have dispose of the lead residues left over from burning boards. Gee, I wonder if there�s a connection between ozone depletion and Danes burning their trash??? I�m thinking of a nine letter word the first letter is "re" and the last letter is "cycling." | | my2� | | Dave F |

Thanks Dave, I agree.

With regard for Brian's credential which are impressive. Evidence has been provided by other serious and respected people to the contrary view of CFC's and ozone depletion. I am not qualified to represent the case they have made, but I have followed it for years.

The whole CFC phase out has been based on probable but not solid science. It has cost billions of dollars, a burden on the global economy. I think they are doing it again with lead.

My apologies for a non technical note, more of a controlled rant. But science is not always as cut and dried as some would have us believe.

Thanks, Boca

reply »

Brian

#10249

Re: solder mask | 15 August, 1999

Boca, Dave

Sorry, but I cannot let this go.

I'll go along with you that, at the time that the Montreal Protocol was initially signed (September 1987), there was no scientific proof that CFCs etc. were causing ozone depletion. There was, however, very strong circumstantial evidence that this was the case and that, if this later proved right, any delay in introducing corrective measures may prove very harmful. The first real scientific proof came just one year later when gas samples taken from the Antarctic vortex by a modified U2 aircraft, flying at 20-30 km, substantiated exactly the simulations produced by practical lab experiments. On the day NASA announced these results, the last remaining scientific doubt fell. The following week, even DuPont acknowledged that Freon was a major contender of ozone depletion and, in a remarkable volte face, announced that it was favourable to a programmed phase-out.

Since then, every scientific advance in the fields of the atmospheric sciences has confirmed that this is so. Today, there are hundreds of universities throughout the world researching the jig-saw of the different sciences, each regularly providing new pieces that narrow down the scope for error and the various interactions between the disciplines involved. To say there is no scientific proof today is to say that the earth is flat. I can't remember all the universities and research organisations involved, but a few of them include University of Cambridge University of Oxford University of Reading University of Edinburgh National Physical Laboratories University of Berne University of Zurich (which has run the oldest stratospheric ozone measuring system in the world, at Davos, since the 1930s) Swiss Federal Institute of Technology WMO WHO MIT University of Illinois Washington State University Colorado State University University of Southern California Irving University (spelling???) Tokyo University Nagoya University Singapore Inst. of Standards Melbourne University and many more. What you imply is that the hundreds of Professors and others who are spending their lives researching this and related phenomena are a bunch of charlatans. Just a wee bittie strong, IMHO. I am not saying that everything is fully understood (if it were, research would not be necessary to fine down the blanks), any more than it is possible for scientists to understand everything about weather or ocean currents, at their current state of knowledge.

On this aspect, there is one peer review process which is the most meticulous in the world: that of awarding the scientific Nobel Prizes. This process is so long that it takes many years between a discovery and the granting of a prize (e.g. 9 years in the case of Watson and Crick for the DNA structure and for Shockley & Co for the transistor). In the case of Molina and Rowlands, they published their original findings in 1974 but did not receive their prize for the study of ozone depletion mechanisms until (I think, � 1 year) 1996. This long delay was because it took the peer reviewers, including a number of devil's advocates, this length of time to become convinced that their original theory was substantiated by scientific proof. In reality, from the first empirical proof, in 1988, to 1996 was actually shorter than average.

I am aware that I'm cutting water with a sword by trying to convince sceptics, but, believe me, the weight of scientific evidence is overwhelming.

By this, I am not saying that man-made halocarbons are the ONLY cause of ozone depletion. There are even natural halocarbons (about 1/3 of the MeBr emitted is natural and there is even natural trichloroethylene in minute quantities). However, these natural sources, including short-lived sulfate aerosols from volcanoes, provide the natural balance of the baseline. With little doubt, commercial and military aviation also cause a small amount of extra depletion. What I can say, very categorically, is that something in the region of 90% of man-made depletion is caused by halocarbons, notably CFCs, carbon tet, halons and suchlike.

To compare such phenomena with cyclamates and plate tectonic or opposing theories is ridiculous. New theories are emitted every day by some persons or groups of persons and which do not hold water. In fact, the US attitude to cyclamates and saccharine, promoted by a quango, was held to ridicule elsewhere. Even today, the strongest selling synthetic sweetener in Switzerland and some other countries is Assugrin which is a mixture of saccharine and cyclamate derivatives. Ozone depletion is accepted in about 180 countries, the signatories of the Montreal Protocol and associated observer states which have not signed (e.g. Vatican, Albania, etc.). There is therefore no comparison.

I'd like to take issue on your "Deep pocketed social engineers at the UN". Before making outrageous statements like this, please check your facts. The UNEP Ozone Secretariat has an anuual budget of less than $10 million. Out of this, they have to pay rent for their premises in Nairobi, Geneva and Bangkok, pay all their staff and finance the annual Meeting of the Parties and the semestrial OEWG meetings, as well as to pay travelling expenses to developing country experts to meetings of the various panels and committees. This is a shoe-string budget and even the Secretary-General of the UNEP OS (the guy who runs it all, a Mr. Sarma) has a salary which would make a Hicksville bank manager with two tellers under his charge blush with shame - in fact, probably less than one of his tellers. Nobody on any of the Panels or Committees is paid for his work or even his expenses (except travelling expenses for a small minority from certain designated developing nations under Article 5(1) of the Protocol). The time and expenses of all these delegates are paid for by their employers, commissioners or, in a few cases, by themselves. I therefore think that your phrase is insulting to the dedication of the thousands of persons and companies involved and who have so generously contributed.

I agree with you that the lead issue in solder is scandalous and that the real solution is recycling. I do not necessarily agree with you that it is of European origin. In fact, the sensitisation about this came from a Bill before the US Congress about 8 years ago (if my memory serves me right) which tried to ban lead in solder then. Fortunately, it did not pass, but it started the technocrats, especially in the Nordic countries, thinking with, as a result, the current propositions. What may surprise you is that lead in solder is not the greatest source of lead pollution from electronics. I have, in front of me, a 21" monitor that weighs 39 kg. About half of this is lead, but I doubt whether there is more than 20 or 30 g of lead in solder in the box. The other 19 or 20 kg is protecting me from X-rays and is in the envelope of the CR tube, notably in the 15 mm thick faceplate. When this monitor or a TV set hits a landfill, it is reasonable to suppose that the tube will break, sooner or later, by the pressure of the bulldozers compressing the rubbish or the weight of the rubbish itself. Lead glass (aka crystal) is notorious for its solubility (hence the bad press for crystal drinking ware) and the shattered tubes will slowly leach kilos of lead into the infiltrating water, much more than the solder in the same monitor, perhaps more slowly, but certainly more inexorably. I have written many articles pro lead in solder with recycling (of glass, as well) but con the indiscriminate disposal of electronic waste into the environment. Unfortunately, mine is a low, lonely voice crying in the wilderness of technocracy.

Sorry if I appear harsh.

Best regards

Brian

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