Glenn (or anyone else), could you elaborate on your statement that slow
rates of change affect solder joints more than fast rates of change.
Thanks,
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
-----Original Message-----
From: Pelkey, Glenn [SMTP:[log in to unmask]]
Sent: Friday, March 08, 2002 3:27 PM
To: [log in to unmask]
Subject: Re: [TN] Thermal Shock
Hi Nancy,
Question 1:
Thermal Shock has some room for interpretation, but in
general, it is a high rate of temperature change. When I say high, I mean
greater than 30 C/min. Even within the mil specs there is some confusion:
Mil-Std-883, Method 1010 is termed "Temperature Cycling" and requires less
than 1 minute transfer time between extremes. However, a similar test
method in Mil-Std-202, Method 107 is termed "Thermal Shock" and allows up to
5 minutes transfer time. Other Thermal Shock test methods use liquid as the
medium of heat exchange rather than air, but I'm assuming you're using air.
Question 2:
If the failure mechanism from the Thermal Shock test is the
same as would be expected in the field, then there is an Acceleration Factor
you can use to relate the two. Just do an internet search for
"Coffin-Manson" for the equation or let me know if you need further help...I
can set you up a quick spreadsheet. However, the key is same failure
mechanism. As pointed out by others in this group, most soldered assemblies
experience slow rates of change, which affect solder joints more than fast
rates of change. But, your end use environment may be different.
Question 3:
I'm not sure what you're asking here. Can you elaborate?
Glenn
-----Original Message-----
From: Nancy Trumbull [ mailto:[log in to unmask]
<mailto:[log in to unmask]> ]
Sent: Friday, March 08, 2002 5:40 AM
To: [log in to unmask]
Subject: [TN] Thermal Shock
Hi Everyone,
It has been awhile for me. I have had so much work that I've
had no time to take part in Technet. So please forgive me.
My Question :
1)What is the equivalent of a Thermal shock cycle?
2) How do I evaluate a failure if it fails with-in 80 cycles?
3) How do I break down a cycle so it would pretain to the
part?
The cycle we have been told to use and evaluate our parts with is
the following:
160 cycles
At -30°C ½ hr ® + 80°C ½ hr
If needed this is an assembled board.
As it is now I can only say it passed or it failed. I can not say
how long the part will last, good or bad.
I have looked in IPC Test Method book TM-650 but could not find any
thing.
Well if any one has any thing let me know. If not I thank each and
every one of you for your time.
Have a good week end.
Nancy T.
----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
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 delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm
<http://www.ipc.org/html/forum.htm> for additional
information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
----------------------------------------------------------------------------
-----
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
