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July 2016

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Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Thu, 7 Jul 2016 06:36:48 -0400
Content-Type:
text/plain
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text/plain (85 lines)
Yes, but didn't you say in an earlier post that you duplicated the problem
in a test oven at 230C? So, the warp happens in two different ovens and
reflow temps? But, not in the ERSA? Sounds like maybe it doesn't happen all
the time? Some of the shields are not stressed.

On Wed, Jul 6, 2016 at 10:34 PM, Deng RongJun <[log in to unmask]> wrote:

> The shield one corner lift about 2-4mm, more solder paste on corner seems
> cannot fix this issue. Because the shielding should be lift/deform before
> solder go to liquid during reflow.
> Current reflow oven is Heller 1890L the old oven with 9 zone, but now we
> put the boards to go through Ersa reflow oven with 10 zone and 3 cool zone,
> then have no issues. Is the profile will effect this?
>
>
> Best regards
> Deng
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
> Sent: Wednesday, July 06, 2016 8:11 PM
> To: [log in to unmask]
> Subject: Re: [TN] Shielding cans deformation during reflow
>
> Deng,
> Besides Bob's good suggestion, here are a few others:
> 1) Relay out the board with a new can shape (yuck)
> 2) Get a new supplier (yuck)
> 3) Have supplier try a slightly different mold shape
> 4) If the can is a square, try turning the can 90 degrees
> 5) Change you stencil and put down more paste in the corners that are
> lifting
> 6) How bad is the lift? If no RF signal is escaping/entering to interfere
> and you are not violating any cosmetic standard, what do you care?
>
> Regards,
> Bev Christian
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann
> Sent: Wednesday, July 06, 2016 5:43 AM
> To: [log in to unmask]
> Subject: Re: [TN] Shielding cans deformation during reflow
>
> Just like BGAs we have found success with small weights (pieces of
> stainless or coins) if such bowing happens.
>
> You have to make sure it is no too much weight else you will solder shorts.
>
> Bob Wettermann
>
> On Wed, Jul 6, 2016 at 1:39 AM, Deng RongJun <[log in to unmask]> wrote:
>
> > Hello fellow Techies,
> >
> > I have got a problem with shielding cans deformation issue. There are
> > several kinds of shielding cans on board, we have found one shielding
> > have deformation after reflow, one side of shielding lift and not
> > solder on board.
> > We also do a test, bake the individual shielding in oven with 230
> > degree, the shielding still have deformation and two corner have lift.
> > Take out
> the
> > shielding from oven and temperature go down, then shielding go back to
> good.
> > Any one of you have experience on this case?
> >
> > Pictures:
> > https://goo.gl/photos/xQLbFT1AEwTR2iV68
> >
> > Thank you very much.
> >
> > Best regards
> > Deng
> >
>
>
>
> --
> Bob Wettermann
> BEST Inc
> [log in to unmask]
> Cell: 847-767-5745
>

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