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Subject:
From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M.
Date:
Wed, 20 Aug 2008 10:01:27 -0400
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Attached is the HASL thickness requirements that were in a
 Jim,



Attached is the HASL thickness requirements that were in a Lucent X-Spec

many years ago.  These thickness requirements were really more in line

of what HASL was capable of providing if you controlled the process

rather than requirements of what we wanted.  Since this X-Spec was first

written there has been a little more control (but not much) to the HASL

process.  If anything, rather than control I believe what occurred is

they would blow a little harder to make sure the HASL was thin for fine

pitch surface mount.  You know the old choices in electronics (Cost -

Quality - Speed pick any two of the three)  Well the big problem I see

with HASL is that you can only have a choice of one out of two (Thin or

Solderable pick only one).







Regards,

 

George

George M. Wenger

Andrew Wireless Solutions

Senior Principal FMA / Reliability Engineer

40 Technology Drive, Warren, NJ 07059

(908) 546-4531 (office) (732) 309-8964 (cell)

[log in to unmask]

 



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey

Sent: Wednesday, August 20, 2008 8:01 AM

To: [log in to unmask]

Subject: Re: [TN] Maximum HASL thickness for SMT of QFN





 

R&D Assembly is a subsidiary of R&D Circuits. Our facility is located in

Allentown PA. Circuits is in South Plainfield NJ. 



I can't answer your question. 



About a year ago Circuits relocated, expanding from a 10,000 sqft

building into a 26,000. I don't think they have turned on the HASL

equipment since the move. 



It isn't often they fabricate a board suited to the finish.







 



-----Original Message-----

From: James Verrette [mailto:[log in to unmask]]

Sent: Tuesday, August 19, 2008 4:58 PM

To: [log in to unmask]

Subject: RE: [TN] Maximum HASL thickness for SMT of QFN



Guy,



Since it looks like you work for a PCB fabricator. Do you know what is

your typical target mean and std deviation for the surface thickness of

SnPb HASL process? 



Thanks,

Jim    



-----Original Message-----

From: Guy Ramsey [mailto:[log in to unmask]]

Sent: Tuesday, August 19, 2008 3:49 PM

To: 'TechNet E-Mail Forum'; James Verrette

Subject: RE: [TN] Maximum HASL thickness for SMT of QFN



I would not recommend HASL, choose one of the flat alternative finishes.





Remember type 3 paste is about 50% solder by volume. A 100 um of

variation in the HASL is more than the total applied volume of solder in

the paste deposit. This type package will not work well with 100%

variation in solder volume in the solder connection. 

You might be successful with 25 um of variation in the HASL finish. 



-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of James Verrette

Sent: Tuesday, August 19, 2008 1:22 PM

To: [log in to unmask]

Subject: [TN] Maximum HASL thickness for SMT of QFN



What is the maximum SnPb HASL thickness/uniformity that can be tolerated

in the SMT assembly of a .5mm pitch QFN package?  Is there anyone else

out there putting .5mm pitch parts on HASL finished boards that is

willing to share their experiences?

 

Jim

Senior Electrical Engineer

 



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