|Ask the Experts|
September 3, 2020
MSD Components Baked Too Long
If MSD components are baked for more time than specified in J Std, can this cause potential failures or other problems? For example, components baked at 125C for 68 hours instead of 48 hours.
|Expert Panel Responses|
The biggest risk of baking too long is loss of solderability. Many parts today have pure (or nearly pure) tin finishes. At high temperature, the intermetallic (IMC) layer between the tin finish and the underlying metal grows, until finally it consumes the entire tin layer, and solderability is irreparably lost.
Before the IMC layer grows through to the surface, the surface will grow a thick oxide layer which will also impede solderability, though not as drastically as exposed IMC.
From a soldering perspective, you could have some issues. Depending upon the plating on the leads and thickness of the plating, extra time in the ovens will enhance the development of the tin/copper intermetallics which will impact the solderability of the leads. This will happen with solid state diffusion.
If the leads are gold plated, the porosity of the gold could allow the nickel underlayer plating to passivate and this would degrade the solderability of the lead.
I'm not sure aboutt he electrical functionality of the product itself but I'm sure there will be responses who address this issue.
Vice President, Technical Director
I really don't see an issue here. Moisture sensitive product can be baked out more than once, so the accumulated exposure, allowed by JEDEC, is sometimes more than 48 hours, say 96 hours in total if baked out twice. So baking the parts for 68 hours does not present excessive exposure.
Global Product Manager
The answer begs the question. Are you asking because you have already baked the parts at the longer stated time & you are questioning whether they are still viable.
Obviously you have gone 20 hours past the spec. Has this caused heat fractures? Internal bond issues?
Component manufacturers spend a great deal of time & money testing & creating specs. My opinion has always been ... stick to the manufacturers specifications... that's why they publish them.
Not being a component engineer I cannot answer the question of have you caused any damage but I think your question should be directed to the manufacturer of the particular part.
|Submit A Comment|
Free Newsletter Subscription
Circuitnet is built for professionals who bear the responsibility of looking ahead, imagining the future, and preparing for it.
Insert Your Email Address