Dry Film Photoresist Processing Technology

Citation

Ellis, B. (2001), "Dry Film Photoresist Processing Technology", Circuit World, Vol. 27 No. 4. https://doi.org/10.1108/cw.2001.21727dae.001

Dry Film Photoresist Processing Technology

Dry Film Photoresist Processing Technology

Karl DietzElectrochemical Publications Limited, IOM432 pp. + xv; 22 tables; 270 figures; 338 referencesISBN 0901150 39 8£85, US$170http://www.elchempub.com/epfiles/ep152.htm

Keywords: Photoresists, Film

My biggest shock when I opened the packet containing this book was the dust jacket: although in the traditional EPL style, it is coloured in the sexiest pink you could imagine, something to do with stripping, perhaps! My second shock was that a book this size could be written about such a specialised subject. A quick glance through will, however, reveal that the author knowledgeably touches on many themes which, although relevant to the main topic, are only incidentally so. This is not a negative criticism, rather the contrary, because it may avoid the reader having to check through more than one book to find an overall solution to a problem he may encounter.

A list of the 18 chapters will reveal the logical sequence and thought processes of the author:

1. 1.

   Photolithography in printed wiring board fabrication.

2. 2.

   Comparison of circuitising [sic!] processes.

3. 3.

   Conductor via (through-hole) formation.

4. 4.

   Initial through-hole metallisation.

5. 5.

   Copper surfaces and base material construction.

6. 6.

   Prelamination surface preparation.

7. 7.

   Lamination.

8. 8.

   Tenting.

9. 9.

   Phototools.

10. 10.

    Exposure.

11. 11.

    Development.

12. 12.

    Electroplating.

13. 13.

    Etching.

14. 14.

    Stripping of aqueous resist.

15. 15.

    Safety and health.

16. 16.

    Waste treatment and disposal.

17. 17.

    Water quality in PWB fabrication.

18. 18.

    Recycling PWB scrap.

Let it be said from the start, if you are seeking information on anything other than the various aspects of negative working, aqueous processed, dry film resists, you will not find much in this work. The author works for one of the major manufacturers of such materials and this does come through, but not too obtrusively. The contents seem incidental to readers interested only in the subject matter of this journal. Nonetheless, in these days of concurrent engineering, it is essential for assemblers to know what goes on in the PCB manufacturer's facility in order to prevent problems in his or, at least, understand what is happening should one unfortunately occur. I therefore maintain that such a review is very apposite to this journal.

On the whole, the contents of this book cannot be seriously disputed, although there are some controversial points, such as the value of the water-break test. The weakest chapter, in my opinion, was that on safety issues, where the high pH stripping baths are not even discussed.

The book itself reaches the usual high standards of the publishing house, both in physical presentation and contents. The author has obviously tried to "go metric", although he is very erratic in his attempts, mixing imperial and metric units within the space of a few lines in some places, or sometimes both.

It is completed with a list of references (not chapter references, as in most of its sister-books) and what I feel is a slightly meagre index. It is required reading in every PCB fab shop that uses, or contemplates using, dry film resists. It should also be in every assembly shop where:

• •

  dry film solder mask is on the boards;

• •

  high-tech assemblies are made;

• •

  where the PCB fab supplier quality leaves much to be desired;

• •

  where concurrent engineering is practised;

• •

  where the potential reader is simply curious about the processes his bare boards have been subjected to.

Now, let's see, just who does that leave out?

Brian EllisCyprus