TECHNET Archives

October 2013

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:
"Stadem, Richard D." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Stadem, Richard D.
Date:
Tue, 1 Oct 2013 16:06:45 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (31 lines)
There is always a thermal shock concern with any ceramic component. However, if properly pre-heated to alleviate any large thermal gradient, the risk of thermal shock is greatly diminished. This is true whether the component is being soldered using wave solder, selective solder, as well as hand-soldering and even in the reflow oven (ramp times must be controlled).
For the selective and wave solder machines, there should not be a huge jump in temperature from the preheat zone to the solder contact spike. There will be a jump, it should just be minimized, and the pre-heat should still be balanced so it is not too hot, either.
Hand-soldering (including touchup after reflow) of leadless ceramic chip resistors and caps and glass diodes should always be done on a hot plate or IR pre-heater to minimize the shock of the iron, if an iron must be used. In any case, training the operator to never actually touch the component itself with the iron should be performed. Getting the operators skilled in the use of a hot air wand is greatly preferred. 
And in answer to your last question: yes, larger/flatter  leadless ceramic components present a greater danger of thermal shock and cracking, because there is less solder under the component endcaps to absorb the contractions/expansions of thermal excursions.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard Krug
Sent: Tuesday, October 01, 2013 10:42 AM
To: [log in to unmask]
Subject: [TN] Wave Solder 2512 Resisters?

Due to business acquisitions we now have an assembly that has been assembled using SMT adhesive followed by wave soldering.  
I know larger multilayer ceramic capacitors are subject to cracking due to thermal shock.  Is there a similar concern with large chip resistors.  

Dick Krug, CSSBB, CSMTPE
Senior Process Engineer
Sparton Complex Systems
30167 Power Line Road
Brooksville, FL  34602-8299
p (352) 540-4012  (Internal Ext. 2012)
[log in to unmask]

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

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

ATOM RSS1 RSS2