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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Re: Handsoldering ceramic capacitor's

Bill Chrisitian

#15263

Re: Handsoldering ceramic capacitor's | 24 June, 1998

| Dennis, thanks for your input. I myself can't remember having any caps fail due to thermal stress/cracking. But the guru's here says it happens and since the assembly is for space flight, it's a requirement to preheat. Also, your process is exactly what our's is for soldering assemblies for ground support, except the temperature range of the soldering iron is 600�F � 35� per NASA-STD-8739.3.

| | Hi Sherry: | | You know, we solder thousands of ceramic caps by hand daily. 1206 to 0402, on rigid and flexible circuits. We have never had a problem with cracking components. The most important item to consider here is to have a temperature controlled soldering iron. Normally you don't need more than 600 degrees F. We normally use 580 to 650 degrees F, depending on the size of the pad. Use a 63/37 type solder and add some liquid flux to help the temperature conduct. This will work faster and save you the time of preheating every board. We see a lot of damage at our facility caused by using the one temperature type of solder guns that range for 700 to 800 degrees F and more. With todays microsized technology, low temp soldering guns are the key. Does anyone know how to find NASA-STD-8739.2. Is it available on the net? I would like to read it.

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Earl Moon

#15265

Re: Wavesoldering Organic Copper Coated Vias | 25 June, 1998

| I have a single-sided board with test vias that pass through the board. The test vias are pasted and reflowed with the SMT components on the top side. When the boards are wavesoldered, the solder coverage on the vias is spotty. Some will solder, others will not. The coating is an organic copper coating (that's what we call it). We are using an aqueous flux. | The major problem is our in-circuit tester will reject a board because the probes don't make good contact. | Some other info: | I sent a raw board through the wave and it soldered much better. (not 100%) | The board layout is divided into two "sections" - one solders well, the other does not. (I'm not sure what's different) | The vias in the different sections are "nested" differently. The vias on the good side are raised off the rest of the board, whereas the vias on the poor side seem to be in the same plane as the board surface around it. (There is a recessed square cut-out area where vias sit) | We have a very similar board with a HASL coating with no reported problems. | I have talked to others who say there is little that can be done to improve soldering bottom-side vias with the organic coating. | Does anyone have more encouraging ideas? | Thanks | - Henry

Henry, Could you be more definitive about "organic" copper? This is an interesting issue if it is what I think. We might all benefit if you could clarify - say from your board supplier just what the "coating" is. Earl Moon

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Henry Lee

#15266

Re: Wavesoldering ENTEK PLUS Coated Vias | 25 June, 1998

| | I have a single-sided board with test vias that pass through the board. The test vias are pasted and reflowed with the SMT components on the top side. When the boards are wavesoldered, the solder coverage on the vias is spotty. Some will solder, others will not. The coating is an organic copper coating (that's what we call it). We are using an aqueous flux. | | The major problem is our in-circuit tester will reject a board because the probes don't make good contact. | | Some other info: | | I sent a raw board through the wave and it soldered much better. (not 100%) | | The board layout is divided into two "sections" - one solders well, the other does not. (I'm not sure what's different) | | The vias in the different sections are "nested" differently. The vias on the good side are raised off the rest of the board, whereas the vias on the poor side seem to be in the same plane as the board surface around it. (There is a recessed square cut-out area where vias sit) | | We have a very similar board with a HASL coating with no reported problems. | | I have talked to others who say there is little that can be done to improve soldering bottom-side vias with the organic coating. | | Does anyone have more encouraging ideas? | | Thanks | | - Henry | | Henry, | Could you be more definitive about "organic" copper? | This is an interesting issue if it is what I think. | We might all benefit if you could clarify - say from | your board supplier just what the "coating" is. | Earl Moon

Earl, As I've added onto the title, by "Organic Copper" I mean the Entek Plus copper protective coating (or OSP). I found out the name right after posting my message. - Henry

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Dave F

#15264

Re: Handsoldering ceramic capacitor's | 25 June, 1998

| | Dennis, thanks for your input. I myself can't remember having any caps fail due to thermal stress/cracking. But the guru's here says it happens and since the assembly is for space flight, it's a requirement to preheat. Also, your process is exactly what our's is for soldering assemblies for ground support, except the temperature range of the soldering iron is 600�F � 35� per NASA-STD-8739.3. | | | | Hi Sherry: | | | You know, we solder thousands of ceramic caps by hand daily. 1206 to 0402, on rigid and flexible circuits. We have never had a problem with cracking components. The most important item to consider here is to have a temperature controlled soldering iron. Normally you don't need more than 600 degrees F. We normally use 580 to 650 degrees F, depending on the size of the pad. Use a 63/37 type solder and add some liquid flux to help the temperature conduct. This will work faster and save you the time of preheating every board. We see a lot of damage at our facility caused by using the one temperature type of solder guns that range for 700 to 800 degrees F and more. With todays microsized technology, low temp soldering guns are the key. | Does anyone know how to find NASA-STD-8739.2. | Is it available on the net? I would like to read it.

Bill: Try the following link. Dave F

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