TECHNET Archives

April 2016

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:
George Wenger <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 19 Apr 2016 00:28:26 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (181 lines)
Ricardo, 

What is the case metal or what is it's CTE? My suggestion is to do XRF measurements of the gold thickness on the connector lead as well as EPd and ImmAg thickness measurements on the PCB as well as a cross section through the temperature cycled solder joint. 

What is your primary concern? Are you just interested in the reason for why you see the movement and the appearance of the solder joint? Or are you afraid that you might actually see solder joint failures in field use? 

George 

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

From: "Ricardo Moncaglieri" <[log in to unmask]> 
To: [log in to unmask] 
Sent: Monday, April 18, 2016 5:57:43 PM 
Subject: Re: [TN] Solder Cracking After Thermal Cicling 

Steve, 
Responding your question. 

Soldered connection is not put under vibration during temp cicling. 

This terminal belongs to a connector which is screwed on a case and its 
terminal passes through this metalic case and lyies on the pcb ENEPIG 
pad. 
So that there are following CTEs playing and intercating each other all 
together: 

PCB CTE 
Solder CTE 
Case CTE where is screwed the conector 
Terminal CTE 

brgds,Ricardo 

>>> Steve Gregory <[log in to unmask]> 18/04/2016 18:47 >>> 
Hi Ricardo, 

I finally have your pictures up, they are here: 

http://stevezeva.homestead.com/A15_Photos_of_pre__post_100_temp_cycling_CSC-10_SN12.pdf 

Boy, that looks like a big CTE mis-match. A question; are the boards 
going 
through ESS? Vibration along with the temp cycling? 

Steve 

On Mon, Apr 18, 2016 at 2:35 PM, Ricardo Moncaglieri < 
[log in to unmask]> wrote: 

> Steve, 
> Attached arethe pictures. 
> Thank you a lot. 
> Await for your comments. 
> brgds,Ricardo 
> 
> >>> Steve Gregory <[log in to unmask]> 18/04/2016 15:22 >>> 
> Hi Ricardo, 
> 
> The Technet server strips the attachments, send your photo directly 
to me 
> and I'll get it posted... 
> 
> Steve 
> 
> On Mon, Apr 18, 2016 at 11:43 AM, Ricardo Moncaglieri < 
> [log in to unmask]> wrote: 
> 
> > Dear colleagues; 
> > 
> > Steve Gregory, could you please upload the enclosed picture? 
> > 
> > Solder become perturbated / cracked after thermal cicling: 
> > 
> > This picture corresponds to a plane (not circular) conector 
terminal 
> > solded to a pcb pad ENEPIG finished. 
> > The connector terminal has been gold removed by twice pretin. 
> > Solder used is Sn63Pb37. 
> > Thermal cicling: 50°C to 125°C 
> > 
> > As picture showed there are stretch marks toward left direction 
and 
> > showed solder crack. 
> > 
> > Our provider reported temperature didnt pass over 125°C and solder 
used 
> > 63/37. 
> > 
> > Question: 
> > 
> > How could these kind of gooves or stretch marks have been produced 
> > taking into account they are just toward one direction (left) and 
of 
> > considerable length? 
> > Just mecanic stress? 
> > Temperature overpassing on any cicle? 
> > Need of use of different alloy, ie.: In, Bi etc? 
> > Provider reported the process is being useed from them since long 
ago 
> > (same solder alloy, temperature, pcb, terminal conector, thermal 
> > cicling) but this is the first time they faced with such a 
cracking. 
> > 
> > Do you have any comment in order to anlyse/solve this trouble. 
> > 
> > Appreciate your feedback we are in middle of a providing 
acceptance 
> > tests space quality level (IPC class 3). 
> > 
> > brgds,Ricardo 
> > 
> > 
> > 
> > 
______________________________________________________________________ 
> > This email has been scanned by the Symantec Email Security.cloud 
service. 
> > For more information please contact helpdesk at x2960 or 
> [log in to unmask] 
> > 
______________________________________________________________________ 
> > 
> 
> -- 
> 
> 
> This email and any attachments are only for use by the intended 
> recipient(s) and may contain legally privileged, confidential, 
proprietary 
> or otherwise private information. Any unauthorized use, 
reproduction, 
> dissemination, distribution or other disclosure of the contents of 
this 
> e-mail or its attachments is strictly prohibited. If you have 
received 
> this 
> email in error, please notify the sender immediately and delete the 
> original. 
> 
> 
______________________________________________________________________ 
> This email has been scanned by the Symantec Email Security.cloud 
service. 
> For more information please contact helpdesk at x2960 or 
[log in to unmask] 
> 
______________________________________________________________________ 
> 


______________________________________________________________________ 
This email has been scanned by the Symantec Email Security.cloud service. 
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________ 
-- 


This email and any attachments are only for use by the intended 
recipient(s) and may contain legally privileged, confidential, 
proprietary 
or otherwise private information. Any unauthorized use, reproduction, 
dissemination, distribution or other disclosure of the contents of this 

e-mail or its attachments is strictly prohibited. If you have received 
this 
email in error, please notify the sender immediately and delete the 
original. 

______________________________________________________________________ 
This email has been scanned by the Symantec Email Security.cloud 
service. 
For more information please contact helpdesk at x2960 or 
[log in to unmask] 
______________________________________________________________________ 


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

ATOM RSS1 RSS2