Greg,



Concerning the EMMA Program, you may want to contact ACI - (610) 362

1200 - directly for their reports. Ask for the Technical Applications

Guidelines (TAG) Handbook. They are available on CD.



Good Luck.



Lee Whiteman, PMP

Senior Member Engineering Staff

L-3 Communications East

Telephone: (856) 338-3508

FAX: (856) 338-2906

E-Mail: [log in to unmask]

 

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

From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman

Sent: Thursday, July 31, 2008 7:56 AM

To: [log in to unmask]

Subject: Re: [TN] Use of QFN devices in high reliability applications



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

[log in to unmask]









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

Sent by: TechNet <[log in to unmask]>

07/30/2008 04:26 PM

Please respond to

TechNet E-Mail Forum <[log in to unmask]>; Please respond to

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





To

[log in to unmask]

cc



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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