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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Tom B

#12772

White layer appearance on PCB | 28 January, 1999

Hello Netters,

I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide enough output (lumens) to cure mask.

Is there a way with out a test lab to be positively certain, that soldermask is the problem?.

Can I bake the PCB's to cure the mask or is there another solution?

Process

1. Kester OA 2331-ZX flux 2. Wave temp 205-215F until 490F 3. Conveyor 4.5ft/min 4. Wash cycle 8min at 145-160F in DI no chemical 5. 3 rinse cycles, 1min at 145F

Thanks

Tom B

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Dave F

#12773

Re: White layer appearance on PCB | 28 January, 1999

| Hello Netters, | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | enough output (lumens) to cure mask. | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | Can I bake the PCB's to cure the mask or is there another solution? | | Process | | 1. Kester OA 2331-ZX flux | 2. Wave temp 205-215F until 490F | 3. Conveyor 4.5ft/min | 4. Wash cycle 8min at 145-160F in DI no chemical | 5. 3 rinse cycles, 1min at 145F | | | Thanks | | Tom B | Tom: Good troubleshooting!!! Sounds like your board fabricator put it to you. He should be doing back-flips to make it right by you. I'm not real excited about you trying to cure these boards. Good luck. Dave F

reply »

Dave F

#12774

Re: White layer appearance on PCB | 28 January, 1999

| | Hello Netters, | | | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | | enough output (lumens) to cure mask. | | | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | | | Can I bake the PCB's to cure the mask or is there another solution? | | | | Process | | | | 1. Kester OA 2331-ZX flux | | 2. Wave temp 205-215F until 490F | | 3. Conveyor 4.5ft/min | | 4. Wash cycle 8min at 145-160F in DI no chemical | | 5. 3 rinse cycles, 1min at 145F | | | | | | Thanks | | | | Tom B | | | Tom: Good troubleshooting!!! Sounds like your board fabricator put it to you. He should be doing back-flips to make it right by you. I'm not real excited about you trying to cure these boards. Good luck. Dave F | Tom: Sorry I ditz'd-out responding to you on the test you should run to test for solder mask cure. Earl chattered about MEK a while ago, but I can't find it in the archive. Anyhow:

1 MEK (methyl ethyl keytone) & acetone are OSHA prohibited, try hypersolve (Great Lakes Chemical) 2 Use citrius terpine cleaners in-stead of MEK

In truth, as I mentioned in an earlier post on this thread get your supplier involved. Your are 95%+ sure it is uncured mask, have him prove it is cure properly.

TTYL

Dave F

reply »

Tom B

#12775

Re: White layer appearance on PCB | 28 January, 1999

Okay,

Another question, if the soldermask in not cured, then it is washed will water ingress (from wash or ambient ) play havoc with capacitance or dielectric of PCB. I mean will my crystal and clock circuits start "Y2K'n" on me. OR will my PCB go from "8080" to "Pentium 450" or resets have extreme "daylight savings time".

All jokes aside, I am concerned that if moisture is "seeping" in will it have deletorious affects on the assembly operation. I would think it should.

TTYL ( I like this sign off !)

Tom B

| | | Hello Netters, | | | | | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | | | enough output (lumens) to cure mask. | | | | | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | | | | | Can I bake the PCB's to cure the mask or is there another solution? | | | | | | Process | | | | | | 1. Kester OA 2331-ZX flux | | | 2. Wave temp 205-215F until 490F | | | 3. Conveyor 4.5ft/min | | | 4. Wash cycle 8min at 145-160F in DI no chemical | | | 5. 3 rinse cycles, 1min at 145F | | | | | | | | | Thanks | | | | | | Tom B | | | | | Tom: Good troubleshooting!!! Sounds like your board fabricator put it to you. He should be doing back-flips to make it right by you. I'm not real excited about you trying to cure these boards. Good luck. Dave F | | | Tom: Sorry I ditz'd-out responding to you on the test you should run to test for solder mask cure. Earl chattered about MEK a while ago, but I can't find it in the archive. Anyhow: | | 1 MEK (methyl ethyl keytone) & acetone are OSHA prohibited, try hypersolve (Great Lakes Chemical) | 2 Use citrius terpine cleaners in-stead of MEK | | In truth, as I mentioned in an earlier post on this thread get your supplier involved. Your are 95%+ sure it is uncured mask, have him prove it is cure properly. | | TTYL | | Dave F |

reply »

Earl Moon

#12776

Re: White layer appearance on PCB | 28 January, 1999

| | | Hello Netters, | | | | | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | | | enough output (lumens) to cure mask. | | | | | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | | | | | Can I bake the PCB's to cure the mask or is there another solution? | | | | | | Process | | | | | | 1. Kester OA 2331-ZX flux | | | 2. Wave temp 205-215F until 490F | | | 3. Conveyor 4.5ft/min | | | 4. Wash cycle 8min at 145-160F in DI no chemical | | | 5. 3 rinse cycles, 1min at 145F | | | | | | | | | Thanks | | | | | | Tom B | | | | | Tom: Good troubleshooting!!! Sounds like your board fabricator put it to you. He should be doing back-flips to make it right by you. I'm not real excited about you trying to cure these boards. Good luck. Dave F | | | Tom: Sorry I ditz'd-out responding to you on the test you should run to test for solder mask cure. Earl chattered about MEK a while ago, but I can't find it in the archive. Anyhow: | | 1 MEK (methyl ethyl keytone) & acetone are OSHA prohibited, try hypersolve (Great Lakes Chemical) | 2 Use citrius terpine cleaners in-stead of MEK | | In truth, as I mentioned in an earlier post on this thread get your supplier involved. Your are 95%+ sure it is uncured mask, have him prove it is cure properly. | | TTYL | | Dave F | Dave,

It was methelyne chloride not methyl ethyl keytone. How some ever, that stuff might work too - just don't have any test methods for that stuff.

You're right about not being able to effect a cure once the mask is applied and the board is shipped. Molecular cross linking must take place within reasonably tight process windows.

And Tom B, I've heard about some problems with this type mask but have no details. However, those things related to fabrication process control more than the mask supplier capabilities. Also, old Dave is right about paying your local sheriff a visit to drive those outlaws out of town or make you some new boards.

Best wishes,

Earl Moon

reply »

Dave F

#12777

Re: White layer appearance on PCB | 28 January, 1999

| Okay, | | Another question, if the soldermask in not cured, then it is washed will water ingress (from wash or ambient ) play havoc with capacitance or dielectric of PCB. I mean will my crystal and clock circuits start "Y2K'n" on me. OR will my PCB go from "8080" to "Pentium 450" or resets have extreme "daylight savings time". | | All jokes aside, I am concerned that if moisture is "seeping" in will it have deletorious affects on the assembly operation. I would think it should. | | | TTYL ( I like this sign off !) | | Tom B | Tom: If these boards will function fine without soldermask, then it's probably OK to use them, providing you (and your boss) don't mind that they look ugly and are willing to put-up with people asking about them for the next five or so years. HAND Ya'hear. Dave F

reply »

Jeff Sanchez

#12778

Re: White layer appearance on PCB | 31 January, 1999

| Hello Netters, | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | enough output (lumens) to cure mask. | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | Can I bake the PCB's to cure the mask or is there another solution? | | Process | | 1. Kester OA 2331-ZX flux | 2. Wave temp 205-215F until 490F | 3. Conveyor 4.5ft/min | 4. Wash cycle 8min at 145-160F in DI no chemical | 5. 3 rinse cycles, 1min at 145F | | | Thanks | | Tom B | Tom, I am jumping on this thread alittle late but here we go. If this cloudy white stuff happens to look like marbled formica than I have had the same problem! Your cure is to use hot air unfortunantly it was the only thing that worked for me and I had hundreds of boards that this happened to.The demon was that stupid water type flux! So for a quick test try using rosin flux on a few of the same boards and walah no more smokey aftermath.Trust me! Then you can scratch your head like I did trying to figure out why your AO 2331-ZX flux did this mean and unsightly thing to you. By the way that was the same exact flux I was using when it happened. If you would like a few gallons I will send them to you free of charge, Just kidding the flux is free but you can pay for the shipping. Back to your problem, I don't know why the flux reacted to the finnish of the board this way but I must point out that if it was the board house not properly curing the mask than what are the odds of us both using the same board house? This is where Earl and Dave should step in....hehe, Why does this type of flux at that temp ( 490 F, exact same temp I run my line at), do this? I am at home so I do not have an MSDS sheet on hand but if we could tell these guys what is in it that may give a clue? Personaly I don't like the 2331, If you like the smell of rotting fish when it's being used than it's a must have..lol Good luck, Jeff Sanchez

reply »

Dennis O'Donnell

#12779

Re: White layer appearance on PCB | 31 January, 1999

| | Hello Netters, | | | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | | enough output (lumens) to cure mask. | | | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | | | Can I bake the PCB's to cure the mask or is there another solution? | | | | Process | | | | 1. Kester OA 2331-ZX flux | | 2. Wave temp 205-215F until 490F | | 3. Conveyor 4.5ft/min | | 4. Wash cycle 8min at 145-160F in DI no chemical | | 5. 3 rinse cycles, 1min at 145F | | | | | | Thanks | | | | Tom B | | | Tom, | I am jumping on this thread alittle late but here we go. | If this cloudy white stuff happens to look like marbled formica than I have had the same problem! Your cure is to use hot air unfortunantly it was the only thing that worked for me and I had hundreds of boards that this happened to.The demon was that stupid water type flux! So for a quick test try using rosin flux on a few of the same boards and walah no more smokey aftermath.Trust me! Then you can scratch your head like I did trying to figure out why your AO 2331-ZX flux did this mean and unsightly thing to you. By the way that was the same exact flux I was using when it happened. If you would like a few gallons I will send them to you free of charge, Just kidding the flux is free but you can pay for the shipping. Back to your problem, I don't know why the flux reacted to the finnish of the board this way but I must point out that if it was the board house not properly curing the mask than what are the odds of us both using the same board house? This is where Earl and Dave should step in....hehe, Why does this type of flux at that temp ( 490 F, exact same temp I run my line at), do this? I am at home so I do not have an MSDS sheet on hand but if we could tell these guys what is in it that may give a clue? Personaly I don't like the 2331, If you like the smell of rotting fish when it's being used than it's a must have..lol Good luck, Jeff Sanchez | I have also had the same problem using 2331ZX. same process, same convewyor speed and solder temp.. It only happens on some boards from specific vendors I use. I think that it is part flux problem, but also mask type or curing problem. I found that dipping the boards in a freon based substitute also removes the cloudy look. I switched to a new Alpha Metals VOC free, water soluble flux. Can't remember the part numer. Works great. Smells like bubble gum, low residue, less bridging, less smoke than the 2331 ZX.

reply »

Jeff Sanchez

#12780

Re: White layer appearance on PCB | 3 February, 1999

| | | Hello Netters, | | | | | | I need some info, Earl or Dave, I have a PCB that exhibits a white layer on solder side. It does not appear to be surface residues (IPA has no effect), but looks like its under solder mask. My first guess is that the LPI solder mask is uncured. I can use solder/hotair tool to heat area and it dissappears. I dug through the archives here and IPC, and found that others have had problems with TAIYO brand soldermask, " WELL Guess What!" My soldermask is also TAIYO (Z-100), which makes me wonder. I am believing that the UV cure thay are using may not provide | | | enough output (lumens) to cure mask. | | | | | | Is there a way with out a test lab to be positively certain, that soldermask is the problem?. | | | | | | Can I bake the PCB's to cure the mask or is there another solution? | | | | | | Process | | | | | | 1. Kester OA 2331-ZX flux | | | 2. Wave temp 205-215F until 490F | | | 3. Conveyor 4.5ft/min | | | 4. Wash cycle 8min at 145-160F in DI no chemical | | | 5. 3 rinse cycles, 1min at 145F | | | | | | | | | Thanks | | | | | | Tom B | | | | | Tom, | | I am jumping on this thread alittle late but here we go. | | If this cloudy white stuff happens to look like marbled formica than I have had the same problem! Your cure is to use hot air unfortunantly it was the only thing that worked for me and I had hundreds of boards that this happened to.The demon was that stupid water type flux! So for a quick test try using rosin flux on a few of the same boards and walah no more smokey aftermath.Trust me! Then you can scratch your head like I did trying to figure out why your AO 2331-ZX flux did this mean and unsightly thing to you. By the way that was the same exact flux I was using when it happened. If you would like a few gallons I will send them to you free of charge, Just kidding the flux is free but you can pay for the shipping. Back to your problem, I don't know why the flux reacted to the finnish of the board this way but I must point out that if it was the board house not properly curing the mask than what are the odds of us both using the same board house? This is where Earl and Dave should step in....hehe, Why does this type of flux at that temp ( 490 F, exact same temp I run my line at), do this? I am at home so I do not have an MSDS sheet on hand but if we could tell these guys what is in it that may give a clue? Personaly I don't like the 2331, If you like the smell of rotting fish when it's being used than it's a must have..lol Good luck, Jeff Sanchez | | | I have also had the same problem using 2331ZX. same process, same convewyor speed and solder temp.. It only happens on some boards from specific vendors I use. I think that it is part flux problem, but also mask type or curing problem. I found that dipping the boards in a freon based substitute also removes the cloudy look. I switched to a new Alpha Metals VOC free, water soluble flux. Can't remember the part numer. Works great. Smells like bubble gum, low residue, less bridging, less smoke than the 2331 ZX. | Bubble gum????, better than dead fish any day!

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