4% rings a bell. can't remember when and where got the number....jk
On Jan 8, 2008, at 3:13 AM, Hernefjord Ingemar wrote:
> How could you write a warpage spec with all hundreds variants of
> boards,
> from a single layer to twelve, size from an inch to fifty, various
> prepregs, variations of components, weight variations and a lot more
> design matters? Seems a little unrealistic to me. We looked for such a
> spec when we started the production of large brass backed teflon
> boards,
> but we did not find a suitable spec.
> Inge
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: den 7 januari 2008 22:10
> To: [log in to unmask]
> Subject: Re: [TN] Warpage of components
>
>
> Most BGAs are built on a FR4-8 circuit board. Like any other FR-4 pwb,
> they can warp for all of the same reasons, copper imbalance, excess
> moisture content, etc. only it is easier for them to do because
> they are
> built on .031 thick material.
> I do find that pre-baking at 105 for 3-5 hours helps quite a bit,
> and a
> longer soak time at reflow also seemed to help. But some BGAs like a
> Universal 366 ball and the infamous Altera 484 I sometimes cannot do a
> darn thing to get them to reflow properly. Likewise, some BGAs do not
> have the potting over the top of the die fully cured, and it tends to
> shrink during reflow. Not much you can do except use shims. But try
> baking first.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
> Sent: Monday, January 07, 2008 2:29 PM
> To: [log in to unmask]
> Subject: Re: [TN] Warpage of components
>
> Thanks, Guy. That's what I told my VP, but he was not inclined to
> believe me.
> Bev
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
> Sent: Monday, January 07, 2008 3:28 PM
> To: [log in to unmask]
> Subject: Re: [TN] Warpage of components
>
> Got a BGA warping on you?
>
> We saw this problem on an Altera Flex484. A contact at Lucent put
> me in
> touch with a package designer at Altera. With his advice we were
> able to
> develop a reflow profile and rework procedure that worked with the !
> @?%%
> thing.
>
> We could not find a JEDEC spec with which to beat the supplier.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
> Sent: Monday, January 07, 2008 9:30 AM
> To: [log in to unmask]
> Subject: [TN] Warpage of components
>
> Technetters,
>
> Are there any IPC or JEDEC specs that talk about component warpage AT
> REFLOW TEMPERTURES?
>
> Bev
>
> RIM
>
>
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