Has anyone experience Power FET leads cutting causing ESD damage to the
die.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Monday, August 07, 2006 8:30 AM
To: [log in to unmask]
Subject: Re: [TN] Lead Cutting/Fractured Solder Joints
Leads had to be cut, a little too long, prior to being sent to
the wave solder, or not cut at all and solder by hand. If wave soldered
the leads were trimmed shorter, which caused the fracture. If the leads
were half clinched towards the outside and then cut to the right length,
prior to being sent to the wave solder, there would not be a need to
trim. Rewaving the boards, as recommended by others will correct the
fracture. Half clinch towards the outside and cut to length will speed
up the process and avoid trimming after solder.
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of P. Langeveld
Sent: Saturday, August 05, 2006 8:28 AM
To: [log in to unmask]
Subject: Re: [TN] Lead Cutting/Fractured Solder Joints
Hi Sue,
Although cutting protruding leads looks very simple, cutting the leads
is more difficult than it looks like.
First of all you need sharp cutting blades.
Secondly during cutting no mechanical force on the solder joint is
allowed. Most of the time one revolves the wrist while cutting and makes
a pull force to the joint that can harm the solder joint. One has to
train to cut without wrist revolving!!!
In my soldering training long years ago I was learned that every lead
cut on a soldered lead in a single sided board has to be resoldered by
hand. Even so when the solder rise in a plated hole had been less than
75%.
Best solution, but not always possible, is to cut the leads to the
correct length before inserting.
Regards,
Peer Langeveld
Consultant Soft Soldering Processes
5502 VH 8 The Netherlands
2006/8/4, Suzanne Runals <[log in to unmask]>:
> We are experiencing fractured solder joints in our manufacturing
> process. We know it is caused from the lead trimming we are doing. We
> do not have automated equipment that will cut and clinch the leads.
>
> I wanted to reflow the boards a second time until we get our process
> under control but not everyone agrees with that. They are afraid of
> damage to the components caused by the heat of the reflow. Has anyone
> else experienced this issue before and what did you temporarily do to
> alleviate the problem while working on the real issue of the lead
> cutting process. I have tried visual inspection but these boards are
> dense boards and we missed some joints and they were returned to us
> again by our Customer.
>
> IPC 610 section 7.5.5.8 states you may reflow and it is not considered
> rework. However they mention nothing about reliability if we do this.
>
> Thanks
> Sue Runals
> QA Mgr.
>
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