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July 2014

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Subject:
From:
Wayne Thayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wayne Thayer <[log in to unmask]>
Date:
Tue, 8 Jul 2014 16:55:10 +0000
Content-Type:
text/plain
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text/plain (47 lines)
Hi Ricardo-

Pix get stripped. Either post them somewhere and provide a link or send them to Steve Gregory ([log in to unmask]), who has graciously offered to post them.

Your email is a bit confusing to me: HASL does not specify solder plating. Solder plating is no longer conventional practice. With HASL, the board is plunged into a very large solder pot, and then hot air jets blow most of the clinging solder back into the solder pot (and blow it out of the through-holes).

So it isn't surprising that the surface is non-planar. We will tentatively use it on "0402" passives, but only if we've qualified the fabricator doing the job (equivalently 1mm pitch BGA). Going higher resolution than this can present problems due to the lack of planarity.

Your verbal description sounds like totally acceptable product, but the pix may say differently.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ricardo Moncaglieri
Sent: Tuesday, July 08, 2014 12:16 PM
To: [log in to unmask]
Subject: [TN] HASL Plated PCB Matter

Dear Colleagues,
I´m working in the aerospace industry at INVAP SE - ARGENTINA and my rol is QA Electronic Service Manager.
Would like to know your comments on following matter:
 
Have requested to a new PCB provider some HASL plated pcb specimens in order to verify its quality and found out what enclosed pictures show:
100% of plated pads have its plating drained or slided off toward the same direction from left to right affecting coplanarity.
As per our visual inspection at first conclusion we stated that it is an Indicator Process (not necessary dewetting related issue) and could be caused between others, from:
1) Pb % degraded.
2) Low air flow temperature trend.
3) Angle of impact of air flow.
 
We asked the provider to define cause of this issue. We didnt do a metallographic analisys to verify Cu6Sn5 presence to confirm intermetallic fusion.
 
We run the J-STD-003 test "C" to verify solderability and it is 100% Ok well wetted, furthermore we soldered a desoldering ribbon (previously tin plated) directly to a pad without using of Flux nor solder and verified that its adherence is very good which indicates pad surface would be well plated.
 
As per your experience: Do you agree with us on our conclusions specially that it seems to be not a strictly dewetting matter?
 
Appreciate too much your feedback on such a matter.
 
Brgds, Ricardo Moncaglieri





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