Hi Amorjot,
You may have two things coming together acting in concert. (1) the SM of your SMD geometry prevents solder from touching until very late in the pass, and then (2) the ground plane simply is too got a heat sink—ergo, insufficient temperature for wetting.

Werner

 


 

 

-----Original Message-----
From: Amarjot Singh <[log in to unmask]>
To: [log in to unmask]
Sent: Thu, Jan 21, 2010 2:59 pm
Subject: Re: [TN] Skipping pads in wave solder


Hi Gang:

My customer is having a problem in wave soldering. The board has surface 
mount and through hole components on top side and there are some test 
points on the bottom side. While passing through wave solder, the holes are 
filling nicely but solder is not being coated on some of the test points. Some 
test points are in the ground plane (solder mask defined) and the others is 
isolated but sorrounded by ground plane. I can cover those pads using solder 
iron without any problems. 

When performing the similar process at some other assembly house in wave 
solder, I noticed the same problem. I played with higher pre-heat 
temperatures, slower and faster speed but same result. Any thought on this 
issue?

Thanks,

Amarjot

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