Yisrael, there is no simple answer to your question. I will however, offer
a few comments.

When considering the best application method, you need to address the
following:
1. Do you have long runs with one panel size or do you have a
number of different panel sizes with varying quantities?
2. Do you process very thin laminates?
3. What panel throughput per hour, per shift etc., do you require?
4. Do you need to plug via holes?

Generally speaking, curtain coating is good for high throughput,
automation, and varying panel sizes. It is not good for thin laminates and
plugging via holes. In addition, because it is a single sided process, some
compromises in drying are made. One side is dried twice and one side is
dried once. This can lead to different appearance and resolution from
side to side.

High volume low pressure spray (HVLP) is also good for high throughput
and varying sizes. Most equipment can handle thin laminates as well. The
two drawbacks are: limited solder mask selection and cannot plug via
holes. HVLP systems are generally double sided and eliminate the
problems associated with a single sided curtain system.

Double sided screen coating systems do not produce as high a
throughput because they are more operator dependent.  Having said
that, I have seen systems produce volumes approaching curtain coating
and HVLP systems, that are run by a skilled operator. There are also
automatic systems now available. The problem is different panel sizes
require set up time. If you have one or two standard panel sizes, this is
not an issue.

 Double sided screen  systems will yield more coverage per kilo. The
process does not need to deposit as much volume of mask to achieve
minimum coverage requirements. This translates directly into lower
coating cost per panel.  Some equipment can also handle thin laminates.
And finally, you can plug via holes with a double sided screen coating
system.

As you can see, there is much to consider before selecting a system
that meets your needs. This is just a short version of the differences
between applications. I hope this information is helpful.

Regards,
Bob Metcalf
Director Solder Mask Systems
Morton Electronic Materials
>>> Yisrael Leshman <[log in to unmask]> 09/05/96 03:52pm >>>
to all SOLDER MASK  TechNeters:


if you had to selecet application methode for LPI coating-:

  curtian coating double sided printing air-spray systems

what would you select.

your  arguments would be appreciated.

thanking you in advance

yisrael  leshman

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