TECHNET Archives

May 2017

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Wed, 17 May 2017 14:17:51 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (1 lines)
Agreed.



-----Original Message-----

From: Fox, Ian [mailto:[log in to unmask]] 

Sent: Wednesday, May 17, 2017 9:11 AM

To: TechNet E-Mail Forum; Stadem, Richard D.

Subject: RE: [TN] IMC Formation Thickness in OSP



Have to agree with these statements. In my opinion the only instance where IMC thickness may impact reliability is under very high g-loading conditions and even then I'm not convinced it would.   Typically joints crack and hence fail in the region of highest strain, which is usually adjacent to a soldered interface whic, is where the IMC is located.  The crack doesn’t typically go through the IMC, it just runs along the interface between it and the solder, well at least it has on the umpteen examples I've sectioned over the last 30 years.



Ian





Ian Fox

Electronics Materials and Process Specialist – Control Systems Civil Aerospace



Rolls-Royce

The Derwent Building, 5000 Solihull Parkway Birmingham Business Park Solihull B37 7YP

T: +44 (0) 121 273 3763

Mob: +44 (0) 7429 673874

E-mail: [log in to unmask]







-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.

Sent: 17 May 2017 14:44

To: [log in to unmask]

Subject: Re: [TN] IMC Formation Thickness in OSP



I could not agree with you more, Dave!

What a lot of people do not understand also is that IMC formation is self-limiting. Rework temperatures do NOT “double the thickness of the IMC and therefore reduces reliability by half” as one solder company’s PhD stated recently when attempting to sell low-melting –point solder alloys. IMC thickness normally has little effect on reliability.



We in the electronics industry have to constantly beware of hucksters trying to make a buck with “easy” technical solutions, only to find you never get something for nothing, and sometimes you get nothing for something more, such as those green RoHS-compliant ESD footstraps for $49 per pair (still laughing and stepping down from soapbox also).

Odin



From: David Hillman [mailto:[log in to unmask]]

Sent: Wednesday, May 17, 2017 8:21 AM

To: Stadem, Richard D.

Cc: TechNet E-Mail Forum

Subject: Re: [TN] IMC Formation Thickness in OSP



Hi Dean - good summary! There is currently a soldering iron manufacturer (who shall remain nameless) who is claiming their system manages the solder joint creation making the "ideal" IMC for a reliable joint. I have requested a copy of the data or research conducted on how the "ideal" IMC for solder joint integrity was derived and am still awaiting the information. I think we are causing some unnecessary waste of industry resources  many times with the topic of IMC comes up. Ok, I'll get off my soap box!



Dave



On Wed, May 17, 2017 at 7:29 AM, Stadem, Richard D. <[log in to unmask]<mailto:[log in to unmask]>> wrote:

Most IMC failures are actually design issues related to delta CTEs between components and substrates, and to varying degrees. I respect the challenge you have of summarizing the perfect storm of these design issues, alloy factors (including nucleation and brittleness), aging, and incorrect or abusive solder joint processes (including rework)  that could contribute or lead to catastrophic SJ failure.



And yet, we all manage to do this every day in this industry.

Dean



-----Original Message-----

From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of David Hillman

Sent: Wednesday, May 17, 2017 7:16 AM

To: [log in to unmask]<mailto:[log in to unmask]>

Subject: Re: [TN] IMC Formation Thickness in OSP



Hi TechNet! I was holding off to see what folks posted. My question is "why does it matter?". An industry colleague and I are collaborating on a paper that covers "industry soldering myths" and intermetallic compound (IMC)  failure is right at the top of the list. Its a true statement that IMCs are brittle but, as an industry, we seem to translate/proliferate that statement into a solder joint defect. There are very very very few industry reports/publications of solder joint integrity failures due to IMC in product use environments. There are tons of reports of IMC failures created because of grossly incorrect or abusive solder joint processes which isn't the same thing. Victor - my suggestion is to focus on having a correct soldering process using acceptable time/temperature parameters regardless if its the initial soldering process or a rework activity. If the solder process is correct, whatever the IMC thickness turns out to be, it will be acceptable.



Dave Hillman

Rockwell Collins

[log in to unmask]<mailto:[log in to unmask]>



On Tue, May 16, 2017 at 4:58 PM, George Wenger <[log in to unmask]<mailto:[log in to unmask]>>

wrote:



> Victor,

>

> I haven't seen and TechNetter responses but I'll give you my two cents.

> The

> IMC thickness numbers you heard sound much too high.  I think the IMC 

> thickness should be half as thick as those numbers.

>

>

> Regards,

> George Wenger

>

>

>

> -----Original Message-----

> From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On 

> Behalf Of 

> [log in to unmask]<mailto:[log in to unmask]>

> Sent: Tuesday, May 16, 2017 8:35 AM

> To: [log in to unmask]<mailto:[log in to unmask]>

> Subject: [TN] IMC Formation Thickness in OSP

>

> Fellow TechNetters:

>

>    What is the acceptable guideline for IMC Formation thickness on OSP 

> after

> 2x rework..   IPC-4555 is still pending.  I've heard of 3-5 microns on

> first

> pass and 5-10 microns on 2x RW.   All comments/suggestions welcomed.

>

> Victor,

>




ATOM RSS1 RSS2