Reply:
Hi, JFB, what a true french name! Sounds as the name of a good liqeur. May I have a glass of Bisonette from 1910. Yum-yum. Also sounds like the name of a small sports car. Marlon Brando used a Bisonette GL in the film Goldfinger.....
Now, you see what an association you went into...poor man, you'll be changed...

OK, sorry for my fiddlesticks..about large ceramic caps, I have seen this and that during the years. First: the bumble-bee cannot fly if you simulate its capability in a avionic calculator program...but the obstinate creature does...does not give a penny (sorry for using this english medevial expression) for the science and takes off like a rocket. In the same way ceramic caps can survive and behave well even in many crazy designs. That is for gamblers to use as an excuse. Making millions of boards and promise 20 years living is something else. So, we have found that a golden rule is :
a) avoid fat solder joints that will drown the cap terminals. The joints should rather be meagre.
b) create a "pedestal" geometry if possible. Can be done by printing a dielectric material under the caps middle section. Or using same method as you do making a solder dam. So, lots of solder does not work, because large caps will sink down in the molten solder, and press the solder aside. Think instead of IBMs C4 process for FlipChip.

The books are filled with pages and pages about the issue, but many a times you just get more confused. If you really want to be knocked down by kilos of reports, I know a guy who has been studying the ceramic cap solderings for years, he will probably give you more precise advice in scientific terms.

Good Luke!

Ingemar Hernefjord
Ericsson Microwave Systems



Hello technetters!

Well thank You for your enthousiastic answers concerning
your identities.  I'll give you some details about my
occupations ounce I get rid of some fires here (it's funny,
nobody mentioned firefighter!!!).

Some people here are getting pretty nervous about one
IPC-A-610 criteria here and honestly I dont know what
what to tell them to ease their worries.

Par. 3.2.4 says that class 1 & 2 permits coating meniscus
of capacitor to be mounted into PTH.  But is'nt there a
risk of preventing the solder to be conform to criteria
4.1 table 1 (saying that the solder must fill 75% of
the hole)?  What is the risk of not respecting this criteria
(3.2.4).  Personnaly I would fear craquing for the capacitor
on the long run (plus the solder fill), this thing will be submit
to constant vibrations (It goes on a train, near the braking system).
So I would prefer to have it above the meniscus.  But here they
are concerned with the overall costing... Well I guess I need
some of these 5000 years of experience now!

Thank You!  See you around!

JF

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