Any more issue£żI am very interesting with it
Jan
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Thursday, November 11, 2010 10:54 AM
To: [log in to unmask]
Subject: Re: [TN] the reliability of capped vias in pads
The 6012C cap requirements are intended to assure a minimal structural
feature. As such, IMO wrap continues to be the most important reliability
feature.
If your fabs are laying down 2-4 mil caps that's a different story.
Chris
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey
Sent: Tuesday, November 09, 2010 10:33 PM
To: [log in to unmask]
Subject: Re: [TN] the reliability of capped vias in pads
Bob,
I don't know I can give definitive proof of but I am pretty sure (good
Engineering reference) capped via in pad can be considerably more reliable
in manual rework than standard pad. With the additional copper going through
the board it should give considerably better resistance against thermal
caused pad lift (more surface area to adhere to board, plus pads on both
sides). I would always be more comfortable hand soldering through hole than
SMT. Due to the mechanical definitions of a capped via I would expect
through hole soldering rules may apply better than surface mount. As to your
specific questions, I think those all must be determined internally
depending on your available skill levels and reliability needs.
Sorry I don't have better, maybe Werner will take a break from golf to
answer.
Hope it helps some,
FNK
Frank N Kimmey CID+
Manager - PCB Design
Powerwave Technologies Inc
Mobile - 916-670-0645
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Landman
Sent: Tuesday, November 09, 2010 10:50 AM
To: [log in to unmask]
Subject: [TN] the reliability of capped vias in pads
A colleague asked me for information about the reliability of capped vias in
pads:
1) How many allowed repairs?
2) Is it acceptable to hand solder wire lead components on those pads?
3) How many allowed repairs are allowed for hand soldered component leads
on thes pads?
4) What is the recommended soldering iron tip temperature? (for lead-free
and tin/lead solders)
5) Is the solder tip "touch up" time controlled well enough by the average
repair technican when done manually to be acceptable or is only reflow
soldering recommended (no rework)?
6) Is the touch up time more variable, longer, when the solder is Lead
Free? (I would say yes it is and we only use eutectic tin/lead solder on
COTS lead-free boards when we do a repair)
7) Are there any restrictions on placing a via in a pad if the component
leads are hand soldered to this pad?
Bob Landman
H&L Instruments, LLC
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