Hi John:

	I agree with your comment regarding the size of the pad. The pad size is
between 1 mm to 1.17mm. There is a function in the wave solder machine
called chip wave. This is used if there are surface mounts on the bottom
side. When this function on, I see improvement in soldering of test pads.
Now, some of the test pads are connected to vias  as these are test points
to test ICs on component side and there are no thermal connections on the
inner layers. Based on your experience, what is the minimum size pad that
can be soldered without any issues. Just to clarify, these are ENIG boards.

Thanks,

Amarjot Singh


-----Original Message-----
From: John Burke [mailto:[log in to unmask]]
Sent: Thursday, January 21, 2010 3:25 PM
To: 'TechNet E-Mail Forum'; 'Amarjot Singh'
Subject: RE: [TN] Skipping pads in wave solder


You need more Z axis wave energy by the sound of it, I have had this problem
in the past (first occurrence 17 years ago) where the solder mask is higher
than the pads and the solder does not touch down on the copper as the system
is at that point airtight if there is no via hole in the test pad.

Increasing wave agitation will fix this or you could consider making the
test points bigge or putting via holes in them which is generally not an
option.


John Burke
(408) 515 4992


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amarjot Singh
Sent: Thursday, January 21, 2010 11:59 AM
To: [log in to unmask]
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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