Last time I looked at J-std-001 (and IEC 61191 is a virtual carbon copy of it), gold removal is only required on through hole, to which I read wave soldered, components when the gold thickness is >2,5um. Personally if its an electrolytic gold finish I'll double dip tin to remove the gold regardless. Whilst the wave will scavenge the gold off the lead in the hole, assuming the pin/hole ratio isn't too tight, it will typically leave it in the top 10% of the hole and lead to premature crack formation
RegardsIan Fox
Lead Materials and Process Engineer
Aero Engine Controls
A Rolls-Royce plc and Goodrich Corporation Joint Venture
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: 31 July 2009 18:06
To: [log in to unmask]
Subject: Re: [TN] AW: [TN] AW: [TN] FORMULA FOR DETERMINING GOLD PERCENTAGE IN A SOLDER JOINT
Who ever made doc and approved it should get shot at... seriously. Not a Friday joke.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jeremias, Michael
Sent: Friday, July 31, 2009 12:17 PM
To: [log in to unmask]
Subject: [TN] AW: [TN] AW: [TN] FORMULA FOR DETERMINING GOLD PERCENTAGE IN A SOLDER JOINT
Unfortunately it is not (!) a typo from me . The document DIN EN 61191-1 contains this value 2,5 µm . But I am not confident, that this is low enough for any process cases so we use for PTH the same rule as above as mentioned below
Sincerely
Michael Jeremias
-----Ursprüngliche Nachricht-----
Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Joyce Koo
Gesendet: Donnerstag, 30. Juli 2009 12:22
An: [log in to unmask]
Betreff: Re: [TN] AW: [TN] FORMULA FOR DETERMINING GOLD PERCENTAGE IN A SOLDER JOINT
Must be a typo. Should be 0.25 micron? 10 micro-inches?
--------------------------
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----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Thu Jul 30 04:26:14 2009
Subject: [TN] AW: [TN] FORMULA FOR DETERMINING GOLD PERCENTAGE IN A SOLDER JOINT
IEC 61191-1
chapter 6.2.2 contains the rules
< 1,4% Volume Au, < 3% Wt Au in the final solder interconnection
< 2,5 µm for PTH Wave soldering (I am not confident, that this is low enough for any process cases so we use for PTH the same rule as above)
You have to take into consideration solder paste volume(stencil-thickness), wetted Au-surface, wetted Au thickness
Own investigations show, that Au brittelness may occure from 1,6% Vol and really will occure from 2,3% Vol.
Sincerly
Michael Jeremias
Industrial Engineering (OPPI41)
Electronics Production
((( Defence Electronics
EADS Deutschland GmbH
89077 Ulm
Tel.: +49 (0) 7 31.3 92-5533
Fax: +49 (0) 7 31.3 92-73 15
E-Fax: +49 (0) 7 31.3 92-20 5533
P Before printing, think about the environment !
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