Aquino, Thanks for your response.
The supplier had provided the information about stencil design to us, like
what you said, the stencil openings are broken into 4 smaller openings and
the area is less than 50％ of pad area.
what’s more, the incoming part has not be found the open issue for solder
joint.
but I think the QFN standoff should be less than some value(3mil?)
Min Jun
H3C process engineer
Tel:+86-010-82774234
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-----邮件原件-----
发件人: Aquino Quek [mailto:[log in to unmask]]
发送时间: 2008年5月8日 7:57
收件人: [log in to unmask]
主题: Re: [TN] QFN's open in SMT power module after second reflow
Modify the stencil opening for center pad with few square and the area
should be 50% of pad area.
Aquino
2008/5/7 Min Jun <[log in to unmask]>:
We recently qualified a SMT power module which has a small QFN part on the
board bottom side （the QFN package is intersil ISL6522 5mm×5mm）.
After the module was soldered to our board, We often found solder jointer
open in QFN terminal for remelting
We also find one doubtful point, in general, if the standoff of QFN has
obviously height and the solder jointer has beautiful fillet,
The module will easily have the open issue after reflow.
So we think the problem reason is caused from the incoming parts PCBA
process control and DFM design although the incoming is good,
Also we think the standoff of QFN in module should be controlled, otherwise
the solder jointer will have open issue in our PCBA.
Who have encountered the same issue or could give me any idea? Thanks in
advance!
Min Jun
H3C process engineer
Tel:+86-010-82774234
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This e-mail and its attachments contain confidential information from H3C,
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intended recipient(s) is prohibited. If you receive this e-mail in error,
please notify the sender by phone or email immediately and delete it!
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Best regards,
Aquino Quek
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