Hi,
Without seeing the photos it really is not possibly to make specific comments.

 Generally, getting nly partial wetting is not good---it indicates either solderability or processing problems,
Werner


 

 

-----Original Message-----
From: Uppina Nagaraj <[log in to unmask]>
To: [log in to unmask]
Sent: Sat, May 29, 2010 12:04 am
Subject: [TN] Query on Solder wetting


Hello All,

We have some issue on the solder wettability
and I need your inputs on this.

One of our customer has informed us that there
is a problem with solder wetting of SMT pads.

The said PCBs are with 1.6mm thick and we've used
63Sn/37Pb for HASL.

We had taken some samples for solder paste printing
and conducted reflow (without component) at our customer's
premises. Our customer is telling us that the solder wetting
is not acceptable to them.

I've attached the photos of the said phenomenon.

I have a few questions on this solder wetting issue.....

a) Is this level of wetting where the solder has not completely
   wetted until the perepheriy of the SMT pads considered
   as reject?

b) If we do a reflow with the components mounted, will the
   components lead "push" the solder paste completely to
   cover the SMT pads completely.

Your reply on the above queries and/or any other relevant
inputs will be of great help to me.

Thanks & Best Regards,
U.Nagaraj

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