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SMT electronics assembly manufacturing forum.


Dave Hammond

#16288

temp stress reliability test for SMT solder bonds | 9 April, 1998

I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice?

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Earl Moon

#16292

Re: temp stress reliability test for SMT solder bonds | 9 April, 1998

| I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice? There have been many such studies both in the military and industry. Do you intend stress or shock or both? I will discuss this issue more off forum if you wish. Earl Moon

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Mike C

#16290

Re: temp stress reliability test for SMT solder bonds | 9 April, 1998

| I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice? Temp ramp tests may not be enough to completly test the joint reliability, you may consider Vibration testing also, I am working with Hobbs Engineering to test some new designs for our fish finders. Contact them at 1-303-465-5988 Hope this helps Mike

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Earl Moon

#16291

Re: temp stress reliability test for SMT solder bonds | 9 April, 1998

| | I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice? | Temp ramp tests may not be enough to completly test the joint reliability, you may consider Vibration testing also, I am working with Hobbs Engineering to test some new designs for our fish finders. Contact them at 1-303-465-5988 | Hope this helps | Mike

I certainly agree with all required testing as thermal stress, thermal shock, mechanical (as vibration and shock), environmental, and electrical. Start with x-ray analysis of solder joints. If volume exceeds 20% you must proceed with all other testing. Also, you must be aware, and have control of, solder process management. If not, all factors will produce defects. Earl Moon

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Earl Moon

#16293

Re: temp stress reliability test for SMT solder bonds | 9 April, 1998

| | I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice? | There have been many such studies both in the military and industry. | Do you intend stress or shock or both? | I will discuss this issue more off forum if you wish. | Earl Moon Correction should be 20% voiding by volume of solder joint by x-ray and/or x-sectional analysis.

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Jean-Paul Clech

#16289

Re: temp stress reliability test for SMT solder bonds | 10 April, 1998

| I am currently involved in a reliability project related to SMT QFP and TSSOP fine pitch solder joint reliability. I have decided to use a temp chamber for stress testing. Is there a test standard that covers this? I am also a bit unsre as to whether my temp chamber can provide the ramp needed to properly stress the solder bonds. Anyone out there gone through this practice? David, One common test that is used in the commercial world is: ramp rates of 5 to 10C/min with thermal cycling air chambers; 0 to 100C (with whatever rate you can get), 5 to 10 minute dwells at the extremes. This gives you 48 to 72 cycles per day. The important thing is to have a test that reflects what your product will see in the field, with adequate acceleration. The test should also lead to failure modes that are identical to failure modes in the field. I am suggesting the above because there are lots of solder joint test results under those conditions (for comparison purposes). My guess is that your QFP solder joints will survive a large number of cycles. If the leadframe of your TSSOP is Alloy 42, you can expect much shorter fatigue lives (on FR-4). Last, once you have your test results, you need an acceleration factor to extrapolate failure rates to field conditions. My company has a software tool (called Solder Reliability Solutions) that can be of help to derive these acceleration factors, as well as to do upfront predictions and optimize your test conditions. The techniques that were implemented in the software have been verified against 50+ experiments, including QFP and TSOP solder joint fatigue failures. Visit my home page (below) or contact me off line if you'd like more information. Jean-Paul Clech EPSI Inc., P.O. Box 1522, Montclair, NJ 07042 tel: (973)746-3796, fax: (973)655-0815

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