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January 22, 2007

Small component rework to IPC spec.

This question is on the "low tech" end of the spectrum compared to most that I have seen here.

We have always prided ourselves on our excellent quality and it has become one of our major selling points. Recently it was pointed out to us that we are not using the approved IPC method for small component replacement/rework.

When doing replacement our associates typically use (and prefer) two soldering irons, one on each side of the component to remove and replace the part. The IPC manual says to use hot tweezers for this task. Is there an inherent problem using the 2 irons vs. the tweezers that could end up affecting our quality?



R.W.

Experts Comments

There is no inherent problem in using 2 soldering irons to remove chip components. Soldering tweezers are simply two irons in one assembly making easier to manipulate when removing the components.

If the operator has the dexterity and the correct size solder iron tips, there is no reason the quality should be any different one way or the other.

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Leo Lambert
Vice President, Technical Director
EPTAC Corporation
At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee.

Irons are easier than tweezers? This is contradictory to my experience, but the end results should be about the same. Note, it is important to not use either method when reworking ceramic chip capacitors. Hot air is the preferred method in this situation.

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Dr. Craig D. Hillman
CEO & Managing Partner
DfR Solutions
Dr. Hillman's specialties include best practices in Design for Reliability, strategies for transitioning to Pb-free, supplier qualification, passive component technology and printed board failure mechanisms.

This is a common solution for removal of two sided devices in the rework area. Some of the common reasons operators use this method are; ease of getting the second iron, thermal capacity of two irons and the unavailability of a tweezers hand piece.

But when you introduce two separate irons into the mix you also add additional variables to the solder joint that can affect quality. Both irons have to be calibrated, both have to be the same temperature and both soldering tips must be the same size and shape.

Any inconsistencies with any of these points can create a damaging thermal delta across the component possibly causing latent damage. The use of a thermal tweezers eliminates these variables and also increases throughput in the rework area, and it makes it easier on the operator.

Finally conductive heating tools must only be used to replace components where solder paste is not used and with components that are rated for the rapid thermal ramp that occurs with soldering irons.

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Edward Zamborsky
Regional Sales Manager
OK International Inc.
Mr. Zamborsky serves as one of OK's technology advisers to the Product Development group. Ed has authored articles and papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead Free Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
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