Karl,
The world is still relying on dry film for inner layer production.  According
to articles generated in the early 1990's, the inner layer production was
going to be 80% liquid by 1996.  This has not happened and in fact the
liquid resist share use has actually diminished since those articles were
written. The main factor behind this is simple economics.  Typically, liquids
generate a lower production yield than dry film.  When loss of base
laminate, production costs, and production time is considered in the yield
loss, the dollar loss can be staggering. 

Most of the world uses either a 1.3 mil or 1.5 mil dry film for inner layer
production.  (SE Asia uses 1.0 mil on broader line technology)  The
reason for this is that yields drop off considerably when resists below
1.3 mil are used.  This is why the liquids at 0.5 mil are having such a yield
problem, in general.

1.3 mil dry film is very capable of producing 3 mil lines and spaces with a
broad process latitude.  Etch rates don't come into play much until the
dimensions of the lines approach the thickness of the dry film.  For
instance the photo chemically machined lead frame industry is using 1.0
mil, 0.8 mil, and 0.6 mil dry film on space dimensions breaking the 1.0 mil
barrier.  We are even investigating thinner dry film coatings than these for
this application.  Outside of Japan, dry film is still the resist of choice for
these fine dimension etched parts.

As far as carinogens, we have had a program in place for several years
to eliminate carcinogens on our MSDS sheets with our new resists.  I
doubt that this type of policy is in place outside of the US manufacturers.

If you would like more information call me in California at 714 730 4200.
Ken Bridges
Product Manager
Primary Imaging Photoresist
Morton Electronic Materials


>>> Karl Sauter <[log in to unmask]> 02/19/97 06:29am >>>

Please advise re latest environmental and performance aspects of
popular photoresists used for etching, primarily for inner layers
including comparison of standard dry film versus liquid photoresists.

The possible photoresist (resist for etching of inner layers) issues
include:

 1) The liquid photoresist is thinner (typical thickness ?);
    a) more prone to handling damage ?
    b) provides controlled trace width (ex: possible 3-mil trace/space
       using an otherwise minimum 4-mil trace/space process) ?

 2) Etch rates (aside from isolated lines with solution movement better
    than for grouped lines);
    a) standard dry film etch rate range ?
    b) liquid photoresist etch rate range ?

 3) Potential problem chemicals such as carcinogens;
    a) does standard dry film contain any at-risk chemicals ?
    b) does liquid photoresist contain any at-risk chemicals ?

Thank you.

Regards,
Karl Sauter
408 276-5499
Sun Microsystems, Inc.



***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to:
[log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact  
*
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************


***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************