[time-nuts] Working with surface mount components

[John Green]

I have been reading the posts regarding working with surface mount
components with great interest. One thing I think I should caution against.
That is soldering capacitors with a soldering iron. Some years ago, when
the folks I work for were just changing over to surface mount from through
hole, I was making all my prototypes using a soldering iron. I used a
fairly low temperature and thought it was perfectly acceptable. That is
until one of my prototypes failed at a customer's location. They called,
returned the part, and demanded to know exactly why it failed. Plus, they
wanted a "corrective action." Those familiar with ISO 9000 will know what
that means. After a brief investigation, I found a capacitor that was
intermittent. I could flex the board and the thing would work. Let it go
and it failed. So, I un soldered the cap and called the manufacturer. I
didn't really expect them to do anything but I insisted on sending the part
back for them to look at. A week or two later, one of their engineers
called me and asked how I soldered the parts. I told him I used a soldering
iron. He said that was my problem. I was causing micro fractures by uneven
heating. He said never, ever solder a surface mount capacitor with a
soldering iron. I took his advice and we have had no more problems with bad
caps. Most of our products are injection molded and we do have a problem
with the plastic blowing inductors off the board during molding. That, and
the plastic drasticlly changes the RF characteristics of the circuit.