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August 5, 2007

Changing PCB finish from FR2 OSP to FR4 HASL-Lead Free

We have changed PCB finish from FR2 OSP to FR4 HASL-LEAD FREE and have encountered pinholes in the PCB solder joints.

We have tried different wave settings but are still unable to solve this problem. We did not have this problem when using FR2 OSP.

Is there a way to keep these pin holes from occurring?



R.B.

Experts Comments

Pin holes as well as blow holes are usually a sign of excess moisture in the PCB or poor PTH plating. The moisture in the PCB heats up over the wave and ruptures the PTH plating, then the steam escapes through the bottom of the fillet causing a pin hole or the larger blow hole.

Bottom line is that you have boards from your vendor that are of poor quality. The only thing that may help you is to bake the boards at 120C for 4-6 hours. If it is just too much moisture this will fix the problem but if the plating in the PTH is bad it may not make a difference. Either way your board vendor needs to work on their process..

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Greg Hueste
Senior Applications Engineer
Speedline Technologies
Greg joined Electrovert in February 1984. Based out of the Electrovert applications laboratory in Camdenton Missouri, Greg has been in the process applications support role since 2000. His primary responsibilities include providing process and machine applications support for the wave soldering lines as well as process, machine and operations training. He also provides applications support for the reflow and cleaner lines. Greg is a PBET certified trainer and holds two patents on wave solder nozzle design.
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