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March 2007

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Subject:
From:
Jack Crawford <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jack Crawford <[log in to unmask]>
Date:
Thu, 15 Mar 2007 16:58:20 -0500
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Because IPC standards are developed by your peers in the industry, staff makes an effort to defer to committee members and technology experts to respond. Lots of messages and it's pretty hard to track every msg to see if anyone has responded.

As suggested in Mike Fenner's response, the content of standards is often carried forward from referenced documents, sometimes of many years and revision levels.

I've just looked at J-STD-006, 006 with Amendment 1, 006A and 006B. The acceptable impurities tables have changed over time in these standards.

For instance, Sn63 with or without antimony, as indicated in various versions by presence or lack of an asterisk or some letter, has always been blank in the Indium column. However, the original release standard and with Amendment 1 have a note "1. Except where otherwise indicated, the component elements in each alloy shall not vary from their tabulated percentage by more than ±0.20 when their tabulated percentage is equal to or less than 5.0..." That would suggest that if the tabulated percentage is "0" that it could have up to 0.20%.

However, in looking at 006A and 006B, that note is missing from the tin-lead tables, but clause 3.2 Alloy Composition states "Except where otherwise indicated, the component elements in each alloy shall deviate from their nominal mass percentage by not >0.10% of the alloy mass when their nominal percentage is =/-1.0%..." so it seems to have tightened a "0" tabulated percentage from 0.20 to 0.10.

I did the same review on J-STD-001B (1996), C (2000) and D (2005) and the contaminant limits table and notes haven't changed. If there's a conflict, it isn't between 001 and 006 but rather within 001 itself, because Clause 3.2 states "Solder alloys shall be in accordance with J-STD-006 or equivalent." yet the table doesn't list Indium as could be accepted by 006. 

The next sentence in J001 gives a way out, but not without some documentation requirements: "Solder alloys other than Sn60A, Pb36B, and Sn63A which provide the required electrical and mechanical attributes may be used if all other conditions of this standard are met and objective evidence of such is available for review."

At this point about all I can add is that J-STD-001 (and 610) have been begun Rev E work. They are both two years old already and in the approx two years it'll take to complete Rev E they'll be near the end of their five-year ANSI life. NOW is the time to submit recommendations/substantiation for changes.

Jack

Jack Crawford, IOM
IPC Director Certification and Assembly Technology
[log in to unmask]
847-597-2893
FAX  847-615-5693
3000 Lakeside Drive, Suite 309 S
Bannockburn, IL, 60015

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Thursday, March 15, 2007 7:40 AM
To: [log in to unmask]
Subject: [TN] Solder Purity


Good morning,
      A little over a week ago I posed a question regarding solder purity
   and a perception of conflict between J-STD 001 & J-STD 006. Luck was not
   with me as there were no replies. Alas, I will try one more time in
   hopes that the tech gurus here can provide some insight or solutions
   based on similar experience.

   Previous post:

   I am hoping that someone can help us with a clarification regarding
   solder purity/composition requirements. Specifically the following:

   ANSI J STD 006 on page 3 lists allowable impurities in the solder alloy
   when purchased. One component in particular is indium @ 0.10 allowable
   limit.
   However, ANSI J STD 001 which is the assembly specification used in
   daily production lists on page 5 allowable solder impurities which does
   not include/allow Indium.
   ANSI J STD 001 which is also the specification used for testing lists on
   page 5 allowable solder impurities which also does not allow Indium.

   Perhaps we are interpreting the sentence associated with the table on
   both 001 and 003 wrong, however the sentence does state:  "the balance
   of the bath shall be lead and/or the items listed above." How can you
   allow Indium in the raw purchased solder and not allow it in the
   production solder?

   Thank you in advance for your thoughts and clarifications.



Brian Guidi
Senior Product Engineer / N.P.I.
Teledyne Printed Circuit Technology
Tel: (603) 889-6191  X:310
Fax: (603) 886-2977
E-mail: [log in to unmask]

Visit us @ http://www.tetpct.com

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