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Wavesolder PCBs encounter pinholes

Thomas

#29544

Wavesolder PCBs encounter pinholes | 18 July, 2004

Hi all,

Need some advice on wavesolder pinholes issues.

The PCBs are stored in a warehouse for 6 months and not vacuum packed. Before wavesodlering, boards are baked 2 hrs at 110 deg. But every piece of it has pinholes at random locations.

PCB is HASL and running on water soluble flux (Solid content : 10 %)

Is there any way I could adjust the wave profile or process before I start the production to prevent this problem ??

Kindly advise

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Thomas

#29545

Wavesolder PCBs encounter pinholes | 18 July, 2004

Hi all,

Need some advice on wavesolder pinholes issues.

The PCBs are stored in a warehouse for 6 months and not vacuum packed. Before wavesodlering, boards are baked 2 hrs at 110 deg. But every piece of it has pinholes at random locations.

PCB is HASL and running on water soluble flux (Solid content : 10 %)

Is there any way I could adjust the wave profile or process before I start the production to prevent this problem ??

Kindly advise

reply »

#29569

Wavesolder PCBs encounter pinholes | 19 July, 2004

Are you talking about small 'volcanos' that burst through PTH solder connections? If so, you have moisture outgassing through the PTH barrels: * Plating on the hole of your bare board is too thin. It should be greater than 1 thou [25um]. * Your bake recipe will do nothing to remove the moisture from your boards. It's too short. [Your "110*" is C, and not F. Correct? ;-)] Search the fine SMTnet Archives for bake recipes.

If this is an outgassing problem, adjusting your wave recipe is a total waste of time. And don't go about trying to "touch-up" these pathetic boards. Your customer will not thank you when they find-out.

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vwhipple@sono-tek.com

#29577

Wavesolder PCBs encounter pinholes | 20 July, 2004

Pin Holes can be caused by many things.

Does the problem come and go?? If so, see if there is a correlation to lot numbers on the boards or vendor. This could indicate a supplier issue.. possibly with the mask.

Look at your soldered assemblies under a scope. Look for board fibers or other contaminants. I recall chasing a "pin hole" issue that turned out to be a contamination issue.

Look at your populated/ unsoldered assemblies under a scope for contaminants.

Dump your flux when you are having the issue and replace with fresh flux. If the problem goes away, this should point you in a direction as well.

What is your measured topside temperature on a board having the issue? Is in the manufacturers recommended range? If not, all bets are off.

As Dave asked, are you at C or F??

Does baking help? if so, what are the differences?

If you have any answers to the above, I will be happy to hear what info you have and see what can be done to help. Or.. I can just repeat my questions. Best of luck, Vince W

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Thomas

#29579

Wavesolder PCBs encounter pinholes | 21 July, 2004

Hi, It is in Celcius. Baking at 2hrs at 110�C , did not help. The problem is consistent and happens at random locations. Fresh flux and new foaming tank has not done the trick also. But I am looking into the contamination issue under scope. The profile is within suppliers recommendation also.

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John

#29581

Wavesolder PCBs encounter pinholes | 21 July, 2004

It is a solderability probems with components or pcb's

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#29584

Wavesolder PCBs encounter pinholes | 21 July, 2004

Thomas,

The first thing I would suggest you to do is identify the type of problem your dealing with �pinhole� or �blowhole� before you can take the appropriate action to correct the problem.

A pinhole is a void or cavity caused by non-wettable parts of the component lead and/or the board plating. If the pinhole is located close to the component the component is the suspect creating the problem and visa versa.

A blowhole on the other hand looks like a small crater and is caused by outgassing, and as Dave mentioned nothing will help to correct this problem except at the source (the board shop).

Out gassing is caused by imperfections in the plating allowing laminate gasses to escape during soldering. The main cause for the imperfections is a poor or non-existing maintenance program for drill change or drill sharpening in the board shop. Unsharp drills create a carbon layer in the holes and since carbon is conductive the plating is incomplete.

A simple way to identify an outgassing problem is to re-heat the defective solderjoint with a soldering iron and watch the bubbling effect when the solder solidifies.

Is your flux water-based or alcohol based and do you have solderballing before cleaning (if not forget about the question).

Hope this helps, Patrick Interflux USA, Inc.

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greg york

#29617

Wavesolder PCBs encounter pinholes | 23 July, 2004

Hi Thomas

Ever considered that this maybe HASL flux left on PCB as this is extremely hygroscopic and has heat transfer fluids that cannot be baked out unless you go to a temperature of around 600C. One way of testing is to leave iron tip on joint and see if a black/dark deposit wicks to the tip there will also be a noticeable smell along with eruptions and popping from the joints. Only way to remove this is to do a saponifier wash followed by rinse then bake and believe me it works. You may also notice shallow inverted solder joints as well.You may also be seeing field failures due to SIR problems or worst case electromigration would also be possible Best regards Greg York Technical Sales Manager BLT Circuit Services Ltd England

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Thomas

#29651

Wavesolder PCBs encounter pinholes | 25 July, 2004

Thanks to all you guys for the advice. I will take your suggestions and work it out. THis is a great site to visit when you are lost in finding a direction. Ha !! Take care guys !!

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Bryan Sherh

#29778

Wavesolder PCBs encounter pinholes | 31 July, 2004

Hi,Please 1.X-ray your board where you found pinholes.perhaps you'll found much voids in your joints,but not only the pinhole.this must be caused by the poor solderability of PCB mostly...or components. 2.Cross-section the pin hole or void in the joints,and to see if you can find the wetting angle is more than 90degrees...if yes...ok... Thanks &Regards! Bryan Sherh

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