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From:
Joyce Koo <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Joyce Koo <[log in to unmask]>
Date:
Thu, 8 Aug 2013 10:37:26 +0000
Content-Type:
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text/plain (97 lines)
50% is sufficient? It depends. What power dissipation requirement, do you have a cool ground or surrounded by hot plane with out escape of the heat? Qfn is for high speed, high dissipation, and low profile requirements.   Otherwise, you will get a BGA or CSP package. My 2cents (prototype is a different story. You out it in the one that easy to debug and measure parameters. Qfn is not bad).

From: Kerr, Bryan (UK)
Sent: Thursday, August 8, 2013 3:55 AM
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] QFN solder voiding


Hi All

Thanks for all the responses. I'm sure that in most cases we have little choice but to develop our processes to suit these problematic component styles however I think the aspirations of the expected soldering standards vary considerably. I think there is a general acceptance that 50% coverage of the base is enough although some people, customers and component suppliers, are beginning to demand more. Peripheral pads are not specified within any standard I know of and these can show a level of voiding too so this still needs to be developed.

Bryan

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: 08 August 2013 01:12
To: [log in to unmask]
Subject: Re: [TN] QFN solder voiding

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From: [log in to unmask]
Sent: Wednesday, August 7, 2013 7:47 PM
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] QFN solder voiding


Steve and all others.
 Void free center pads are achievable but you have to really think out of the box to arrive at a solution. I have worked with parts 1.6mm square to parts as large as a postage stamp and the same basic techniques work.

Helpful hints;
Solder mask is your enemy and the proper aperture will look very different than what you usually see.
 Little blocks of solder paste will only result in voids.
Think out of the box.

Due to my work I really cannot reveal the secrets but the results can be achieve.

John

 On Wed, 7 Aug 2013 14:12:02 -0600, Steve Gregory <[log in to unmask]>
wrote:
> (background chorus) I want my...I want my...parts void free!
>
> Steve
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey
> (EHCOE)
> Sent: Wednesday, August 7, 2013 1:47 PM
> To: [log in to unmask]
> Subject: Re: [TN] QFN solder voiding
>
> Striking a familiar chord; Excellent!
> Dewey
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