Here are my comments on two technology information sources which have been
around for a few months. The publishers some times take a little time to get
them to my office in sunny Chelmsford, Essex, England its out in the sticks a
lot of cart horses out this way and it takes time for the mail to get to me..
Flip Chip Technologies By John Lau
Yet another book co-ordinated by John Lau, we will all need a book shelf just
for his books soon. The use of direct chip attachment has been available as an
assembly technique for many years. Pressure from customers, design engineers and
now wider commercial availability of good silicon is making it a more accessible
technique.
As this reviewer is currently completing a new video tape on "Chip on Board"
this relatively new publication is of great value as a reference. Chapters cover
high and low pin out devices, bumping techniques, soldering, conductive
adhesives plus test and quality assurance of the die. All in all an A-Z of the
technology.
The first chapter is an introduction to the whole technology, ten pages contain
a listing of just some of the patents. The technique dates back to the early
1960s when IBM looked for a replacement for wire bonding as an interconnection.
An interesting chapter examines the many benefits of polymer interconnection.
Details are given of the compatibility issues of different substrates. There
are may references to the type of joint formation. In many instances the joint
structure can be complex. Each case is well explained as well as highlighting
the possible failure modes. This material is well illustrated with many diagrams
and sections. It is interesting just how many different methods are available
for flip chip interconnection. Things have moved on a way from the original
collapse bump technology.
A good book, a little heavy on some of the reliability stuff but that's my poor
understanding of the subject. Its well illustrated but could have done with more
practical application examples. Comparing how similar companies in similar
markets approached its commercial use.
Very good book worth the investment.
(Its about time John invited me for a beer all the nice things I say).
No Clean Technology published by Elsevier
This no clean report was produced in late 1995 to provide a complete overview of
the issues leading to the wide adoption of no clean low residue fluxes. Well it
is fair to say that the swing to no clean has be large. The last SMART Group
survey put the percentage of companies with a no clean policy at over 80% of the
market.
The report covers the whole story of why eliminate cleaning, Montreal Protocol,
technology trends, no clean materials, equipment and other references. For a
report on no clean there is a lot of material on cleaning which should have been
confined to jig, stencil and manual techniques. It is a useful source of
information on the whole story but engineers need more practical information on
the problems and how to over come them.
There are a lot of issues highlighted but not may solutions provided. One of the
main issues with no clean is solder mask compatibility and solder balling which
get very little coverage. Its a useful source of material but too expensive at
L295.
(Reviewers Note. Congratulations to the Elsevier team behind the report for its
completion, you did it, I didn't).
Bob Willis
Electronic Presentation Services
2 Fourth Avenue, Chelmsford, Essex CM1 4HA. England.
Tel: (44) 01245 351502
Fax: (44) 01245 496123
Home Page: http://our world.compuserve.com/homepages/bwillis
Email: [log in to unmask]
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