Hi Jon:
Solder wicks up between the walls of the Throughole
and the leads. It has been said in this forum that lead free solder has
a harder time to wick up the same as 63/37, but only 75 vertical fill is
expected to be within spec. Also the machine's requirements need to be
accommodated. Build a small batch of boards, inspect and make
adjustments, if they are called for, perhaps adjust the hole down 3
mils. You are in unknown territory.
Best of Luck,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, January 30, 2006 3:49 PM
To: [log in to unmask]
Subject: Re: [TN] Optimum dia of thru-holes
Jon, I noticed that you are not getting any replies. It may be that no
one has addressed this particular issue with that much of a hole aspect
ratio difference yet with Pb-free solder.
A hole diameter .020" larger than the lead is on the high end of the
ratio for a standard .062" board thickness. There are standards for this
listed in IPC 6012 and elsewhere. But they deal with 63/37, and this may
have to be re-visited with Pb-free solder.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jon McDowell
Sent: Monday, January 30, 2006 1:08 PM
To: [log in to unmask]
Subject: [TN] Optimum dia of thru-holes
Group
I recently sent the message below, and would like to ask another
question. For SAC305 what is the optimum over sizing of though holes,
as compared to the lead diameter.
Hello group
My name is Jon McDowell, and I work as a Quality Technician at ECCO in
Boise ID. We manufacture back-up warning alarms for the auto/truck
industries.
I have a question for you.
We are using the Pansert AVKII through hole insertion machine, which
call out that the diameter for through holes be .020 larger than the
upper tolerance of the wire diameter being inserted in that hole.
However I have been informed that a hole which is .020 over the lead
diameter may cause problems with soldering, particularly with the SAC95
solder. Can anyone advise on this.
Thank You
Jon McDowell
Electronic Controls Co (ECCO)
833 W Diamond St
Boise Id 83705
P 208 395-8025
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