Jowan,
I think you need to do two things:
1. identify the plating material and measure its thickness on the shoulders of the leads on a new non-soldered component.
2. Cross section a new non-soldered component as well as one that shows the shorts through one of the leads.
I think what is happening is that there is too much plating on the leads and when you put the component through reflow the plating that is on the portion of the lead under the molding compound melts and gets pushed outward to the shoulder and there is enough to short to adjacent leads. I've seen this happen one in the past.
Regards,
George
George M. Wenger
Andrew Solutions
Senior Principal FMA/Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 (Office) (732) 309-8964 (cell)
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Iven, Jowan
Sent: Monday, June 28, 2010 8:53 AM
To: [log in to unmask]
Subject: Re: [TN] QFP short at top of the leads
Jerry,
The component was not dipped before placement
In the picture you can see the original component placed on top of the
soldered one. It's not dipped.
Jowan
-----Original Message-----
From: Jerry Dengler [mailto:[log in to unmask]]
Sent: maandag 28 juni 2010 13:40
To: TechNet E-Mail Forum; Iven, Jowan
Subject: RE: [TN] QFP short at top of the leads
Jowan,
Was this part dipped in solder before placing? It looks like solder has
coated the whole lead right up to the body.
Jerry
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Iven, Jowan
Sent: Monday, June 28, 2010 5:08 AM
To: [log in to unmask]
Subject: [TN] QFP short at top of the leads
Has anyone ever seen a QFP where shorts occur after soldering at the top
of the leads?
And the leads look pretty dull after soldering. Any ideas?
A picture is available at
http://ipc-technet.groupsite.com/uploads/galleries/x/000/020/5ba/technet
01.jpg
Jowan Iven
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