Agreed.  It's funny how it is assumed lead-free components are bad all
of a sudden.  Reality is that we have had some lead-free component
finishes in use for decades - Texas Instrument's NiPd finish on their
SOIC type parts jumps to mind.  

We are majorly concerned with two classes of lead finish for use in our
assemblies:
 - pure tin finish in any form
 - BGA parts with non PbSn balls (e.g. a BGA with SAC alloy balls)

but you (Badri) really need to evaluate it on a part by part basis. 
Even if the part is acceptable from a reliability perspective, it may
solder differently and therefore require a modified process relative to
your regular production.  

 - Graham C

>>> [log in to unmask] 05/10/07 01:10PM >>>
It really "depends" and doesn't seem to have as much to do with
solderability as it does with the dreaded tin whiskers. We don't do
medical but we do some DOD and they are hell on tin whiskers and tin
finished component leads.

KennyB

-----Original Message-----
From: John Burke [mailto:[log in to unmask]] 
Sent: Thursday, May 10, 2007 8:45 AM
To: [log in to unmask] 
Subject: Re: [TN] PCB assembly for medical devices

WOW,

Before someone says "it depends" can I just point out that the medical
device manufacturer should be controlling the BOM and also should in
most
cases be requiring FDA tracking of the actual components used in the
assembly.

John

 
 
John Burke
 
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of BADRI
Sent: Thursday, May 10, 2007 6:01 AM
To: [log in to unmask] 
Subject: [TN] PCB assembly for medical devices

Dear All,

We have just started assembling some PCBA's to a medical device
manufacturer. They hate lead free. The question is as follows:

The components are leadfree and the paste used is leaded. Is it ok or
do
I
have to pretin all the components with lead and then process. 

We have processed couple of boards without pretinning and we have not
faced
any issue. Will the devise manufacturer accept it.

Please advise on the right process.

Advance thanx

Badri

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