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