Rob,
Firstly, presence of a toe fillet would nicely complete a near perfect
solder joint where fillets are concerned. I don't think IPC specifically
references toe fillets - the existence of a heel fillet being mandatory with
side fillets present to varying degrees due to allowances for side overhang
etc. Heel fillet height being determined by solder bed+lead
height/thickness.
However our recent experience with leads on some ICs is that the toes edge
does not always solder well as some leads are not coated at this end -
probably due to lead cutting during the fabrication process.
Grant
-----Original Message-----
From: Rob Day [mailto:[log in to unmask]]
Sent: Wednesday, September 26, 2001 2:09 PM
To: [log in to unmask]
Subject: [TN] solder reflow question
Hello folks,
We have a problem with some IC's and solder quality on a board that we are
running. The inspector told me we had problems with the toe solder joints.
The reflow throughout the rest of the board looks pretty good. This solder
problem around the IC is not a consistent one. The solder is not rejectable,
but we would like it to look better.
I have tested our profile with some profiling tools and the profile is very
good. Our paste is only 1 day old. Could it be some of the pads on the raw
board?
Is there anything else that you folks would check as part of a typical
problem solving approach as I am relatively new to the industry.
Your comments would be greatly appreciated.
Thanks,
rob day
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