TECHNET Archives

November 1998

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Jim Marsico 516-595-5879 <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 11 Nov 1998 08:18:00 -0500
Content-Type:
TEXT/PLAIN
Parts/Attachments:
TEXT/PLAIN (65 lines)
We went into production with a similar component few years ago, with the same
start-up problems.  We use a ceramic 164 quad flat pack (QFP), which we form
the gull wing leads in-house, for a military application.  To answer your
questions:

1) I have been dealing with Fancort Industries to design a die for stamping
out the Gull wing form. Are there any other companies who specialize in
forming equipment for this kind of part ?

We also use Fancort and had good success.  There are others out there... Knight
Tool comes to mind.

2) Is there a correct pad geometry for this part ?? IPC spec ?? Reference ??

The pad geometry is directly related to your lead foot design.  Our pads are
.110" x .015".  This accommodates a .050" long foot that is .012" wide.  The
pad length ensures that we meet the heel-to-end of pad requirement in
MIL-STD-2000.

3) Anybody out there familiar with the process that I've just described ?
Hopefully there's someone out there in a "been there, done that" mode that
can give me some pointers.

Been there, done that.  That's why we have switched most of our QFP devices
(except 1 QFP164) to BGAs.

4) Among the users of CQ132 QFP's, have you used your parts in a military
environment capable of meeting vibration and thermal requirements ??

This depends on your environment.  Our Finite Element Analysis (FEA) showed
that thermal (temperature cycling) wasn't a major problem (as long as we used
the .050" long foot), but vibration was.  To compensate, we had to design our
lead bends for a shoulder length (distance from the component body to the first
bend) of .090".  We also had to use a thermal adhesive under the component for
both heat dissipation and stability for vibration.  Just imagine how difficult
it is to maintain lead coplanarity with leads that have a .090" shoulder and a
.050" foot!  Needless to say, due to the lead planarity concern and the thermal
adhesive requirement, these parts were not installed automatically.

5) Anybody with forming equipment out there who can tell me how easy or
difficult it was to generate a die design ?? Any advice ??

Fancort does the die design.  Just give them the lead bend dimensions and
they'll do the rest.


If you want to discuss this further, please call or e-mail me.

Jim Marsico
AIL Systems Inc.
(516) 595-5879
[log in to unmask]

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################


ATOM RSS1 RSS2