TECHNET Archives

January 2011

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:
Werner Engelmaier <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Werner Engelmaier <[log in to unmask]>
Date:
Mon, 3 Jan 2011 22:06:37 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (411 lines)
 
Hi John,
Being in an airport kept my answer brief, too brief.
This is not an altogether trivial question; I dealt with it in detail in one of my reliability columns in Global SMT &Packaging magazine: 

 
 Engelmaier, W., “SolderJoint Reliability Prediction for Chip Components, MELFs, TSOPs, SOTs, etc.,” GlobalSMT & Packaging, Vol. 9, No. 6, June 2009, pp. 30-32.  I have attached it for your convenience [the rest of the 'Netters need to ask for it or get it directly from the GSMTP website, since IPC strips attachments].
Werner

 

 

-----Original Message-----
From: Werner Engelmaier <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, Jan 3, 2011 2:40 pm
Subject: Re: [TN] solder joint height values (h) for leadless SMT components?



 Woah John,

You sure need to read the parameter definitions again. Whatyou are refering to 

is fr compliant 'leaded' components, not leadless. For leadless, you had better 

measure h; fllets do not count.

Please read IPC-D-279 or one of my papers.

Werner



 





 



 



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

From: Nieznanski, John A - GS <[log in to unmask]>

To: [log in to unmask]

Sent: Mon, Jan 3, 2011 1:24 pm

Subject: [TN] solder joint height values (h) for leadless SMT components?





Happy 2011 TechNetters!







The solder joint height parameter "h" is a very sensitive parameter in the E-W 



solder fatigue equations per IPC-D-279 and IPC-SM-785, particularly for leadless 





components.







For leadless components, it is common to use half the solder stencil height for 



"h", in lieu of measured values. So for example, given a 6 mil thick solder 



stencil, "h" is often assumed to be 3 mils with some acceptably small 



variations, to be quantified and confirmed.







However there are many leadless SMT components that have solder joints that can 



not be characterized by a single "h" value. For example, SMT resistors often 



have a solder fillet that is between 50% and 100% the thickness of the component 





along the outside edge of the terminals and much less under the terminals. 



Similary for leadless MELF diodes and castellated LCC packages.







Ideally it would be great to build test boards with all these configurations to 



get failure data and correlate these results with DPA measurements of solder 



joint cross sections. Are you aware of any published papers that discuss this 



type of analysis and/or attempt to derive and correlate an "effective h" for 



leadless component types and terminals based on measurements?







In lieu of any published efforts, does it seems plausible or reasonable to 



develop the concept of an "effective h" or "average h" based on several design 



and assembly parameters such as solder pad dimensions, wetted terminal 



dimensions, solder stencil thickness, component-to-pad misregistration, etc? Is 



this just wishful thinking? Alternatively, I suppose one could make the "weakest 





link" argument and say that the "minimum h" is going to dominate the behavior of 





the solder joint, not the "average h" or "effective h", since the "minimum h" is 





where the shear stresses and strains will concentrate and initiate wearout.







Thanks in advance for any results, comments, thoughts or suggestions that you 



can provide............







Regards,







John Nieznanski











________________________________



This e-mail and any files transmitted with it may be proprietary and are 



intended solely for the use of the individual or entity to whom they are 



addressed. If you have received this e-mail in error please notify the sender.



Please note that any views or opinions presented in this e-mail are solely those 





of the author and do not necessarily represent those of ITT Corporation. The 



recipient should check this e-mail and any attachments for the presence of 



viruses. ITT accepts no liability for any damage caused by any virus transmitted 





by this e-mail.







______________________________________________________________________



This email has been scanned by the MessageLabs Email Security System.



For more information please contact helpdesk at x2960 or [log in to unmask] 



______________________________________________________________________







---------------------------------------------------



Technet Mail List provided as a service by IPC using LISTSERV 15.0



To unsubscribe, send a message to [log in to unmask] with following text in



the BODY (NOT the subject field): SIGNOFF Technet



To temporarily halt or (re-start) delivery of Technet send e-mail to 



[log in to unmask]: SET Technet NOMAIL or (MAIL)



To receive ONE mailing per day of all the posts: send e-mail to 



[log in to unmask]: SET Technet Digest



Search the archives of previous posts at: http://listserv.ipc.org/archives



Please visit IPC web site http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums 





for additional information, or contact Keach Sasamori at [log in to unmask] or 



847-615-7100 ext.2815



-----------------------------------------------------





 



______________________________________________________________________

This email has been scanned by the MessageLabs Email Security System.

For more information please contact helpdesk at x2960 or [log in to unmask] 

______________________________________________________________________



---------------------------------------------------

Technet Mail List provided as a service by IPC using LISTSERV 15.0

To unsubscribe, send a message to [log in to unmask] with following text in

the BODY (NOT the subject field): SIGNOFF Technet

To temporarily halt or (re-start) delivery of Technet send e-mail to 

[log in to unmask]: SET Technet NOMAIL or (MAIL)

To receive ONE mailing per day of all the posts: send e-mail to 

[log in to unmask]: SET Technet Digest

Search the archives of previous posts at: http://listserv.ipc.org/archives

Please visit IPC web site http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums 

for additional information, or contact Keach Sasamori at [log in to unmask] or 

847-615-7100 ext.2815

-----------------------------------------------------


 

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

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2