Hi Rod,
I hope you could reach to the following papers.
Regards
ilknur Baylakoglu
Author(s): Scheer, F.; Crane, L.
Corp Source: McCurdy Circuits, Orange, CA, USA
Title: The advantages of electrostatically sprayed LPI solder mask for the
fabrication and assembly of high density SMT boards
Source: Surface Mount International, Conference and Exposition. Proceedings
of the Technical Program p. 2 vol. 1306, 922-5 vol.2
Publication: USA
Language: English
Publisher: Surface Mount Int; Edina, MN, USA
Conference Loc: San Jose, CA, USA; 27-29 Aug. 1991
Year: 1991
Treatment: P Practical
Record Type: Conference Paper
Abstract: While the use of dry film solder mask has allowed for the increased
use of SMD technology there are still areas of issue from both a fabrication and
a board assembly standpoint. While dry film solder mask has improved the
fabricators yield it is in fact the requirements of the assembly house, which are
further driving the search for improved, solder mask technology. The search for
improved assembly and fabrication yields has led to the use of liquid
photoimagable solder masks (LPI). The main focus of this paper is on the
advantages of LPI technology over dry film and the advantages of
electrostatically spraying the LPI over other methods of application and what
these advantages mean for both the fabricator and the assembler/end user (0
Refs.)
----------------------------------------------------------------------------------------------------------------
Author: McGregor, D.R.; Hull, R.B., Jr.; Petersen, R.N.
Corp Source: Du Pont Electronics, Research Triangle Park, NC, USA
Title: Solder mask and SMT solderability
Source: Printed Circuit Fabrication, vol.15, no.12 p. 30, 32, 36-7
ISSN: 0274-8096
CODEN: PCFAE6
Publication: USA
Language: English
Year: Dec. 1992
Treatment: P Practical; X Experimental
Record Type:Journal Paper
Abstract: The major difference between dry film and liquid photoimageable (LPI)
soldering yields has been ascribed to the difference between the height of solder
dams and that of SMT pads. Dry films have solder dams higher than pads while
LPIs have dams lower than pads. To study the effect of solder dam height on
soldering performance, nine solder masks were benchmarked for reflow and
wave soldering. The benchmark test included high-conformation dry-film, liquid-
dry, and LPI solder masks, which provided a range of mask thicknesses
adjacent to SMT pads. This article presents the test vehicle, methodology, data,
and conclusions (0 Refs.)
On 30 Oct 00, at 15:07, IPCsm840 Rod Simon wrote:
> I am looking for some information on dry film soldermask vs. LPI
> soldermask.
>
> Manufacturing wants to change all boards to dry film mask and tent all via
> holes so that when conformal coating is applied to the boards the coating
> does not drip through the holes.
>
> About 2-3 years ago I remember reading an article on problems with dry film
> and alternatives to using dry film. Since I had only used dry film once or
> twice a long time ago I did not save the information and can'
>
> t find it in
> any back issues of Printed Circuit Design or SMT that I have.
>
> It is my understanding that our main supplier has the facilities to dry
> film and is encouraging the dry film solution. (In my opinion more $ and
> less Competition) Cost is not a big issue since we do not produce large
> quantities of our products.
>
> Any help would be greatly appreciated.
>
> Rod Simon
>
> [log in to unmask] Flight Vision Inc. Sugar Grove IL 60554
> 630-466-2119
>
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