Hi Greg - I recommend you conduct a literature search for published papers 

on the following project:



Electronic Miniaturization for Missile Applications (EMMA)

Time frame: October 2001

Funding Agency: American Competitiveness Institute



A QFN style device was included in the EMMA study which conducted both IPC 

Class 3 thermal cycle and vibration testing as part of their assessment 

program of SMT components. The data you are looking for is included in the 

EMMA reports. Good Luck.



Dave Hillman

Rockwell Collins

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"Temkin, Gregg" <[log in to unmask]> 

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Subject

[TN] Use of QFN devices in high reliability applications













Our team is working on several new electronic devices whose application is 

primary, flight critical hardware for commercial aircraft.



Our initial component selection includes many QFN packaged devices 

(leadless, bottom side termination only) which will be mounted on .063" 

FR4 boards using SN63.  The devices range from 20 to 44 terminations.



From studies that are available on the web, a picture has emerged that QFN 

packages have reduced long term solder joint reliability when compared 

with leaded or some of ball grid array devices.  Board thickness, flexing 

and whether the device has a central solderable heat sink seem to have a 

significant affect on reliability.  Problem is there are no absolute 

numbers, so for critical applications it seems that thorough testing is 

required.  We'd rather not wait until the end of a lengthy test regimen to 

find we've gone down the wrong path.  Is there newer information 

abbailable?   Two of the studies stated that further testing was being 

performed to support the reliability requirements for aerospace and other 

high-rel applications however I cannot find any updated information on the 

web.



We have decided to replace several of the QFN's with leaded devices, 

however there are no direct crosses for 3 of the devices. One of them will 

require a number of components to create the same function; possibly an 

additional circuit card.



Is anyone aware of information or recommendations that would be useful for 

our assessment?  Is there any specific information that would drive us to 

use or not use them?



Thanks for your help



Gregg













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