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SMT electronics assembly manufacturing forum.


OSP and getting full pad wetting??

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#71973

OSP and getting full pad wetting?? | 17 April, 2014

Hello All....we have several hundred PCBs that we need to run with a no-clean solder process and the surface finish is OSP. Our preliminary testing has found that the solder will not wet the entire pad even if the pad is over printed? We have contacted the solder paste provider but information is slow in coming and these PCBs are not going to go away. These PCBs came from either China or Taiwan so we are not sure which OSP they are using. Anyone with any pointers no matter how trivial please put in your 2 cents please....Thanks Anvil

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#71979

OSP and getting full pad wetting?? | 18 April, 2014

what is the technology? Is there fine pitch, double sided, number of layers, lead free? If the pcbs are not of the highest quality you may be set up for failure with no clean process. Couple things to look at is your paste flux content versus medal content. Higher flux content might help. Also make sure ramp and soak temps on profile are not to high, or you will flash off the flux before it gets the job done. I was in contract manufacturing and basically refused to build OSP. Anyhow good luck.

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#71981

OSP and getting full pad wetting?? | 18 April, 2014

Methods that can reduce the wettability of OSP: * Previous heat cycles * Previous cleaning cycles * IPC-1601 "Printed Board Handling and Storage Guidelines" says do not bake prior to soldering * Using improper handling methods

BR ... davef

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