Membrane Switch Catalogue - Bergquist Company - #8

Standard 3 x 4 matrix switches 2.6" x 3.0" with 3" tails are used for testing. All switches are constructed one month prior to any testing. Spacers tested are as follows:

1) Bergquist HeatSeal spacer - .008" total thickness (.005" base polyester with .0015" of HeatSeal adhesive on each side).

2) Pressure sensitive acrylic spacer - .009" total thickness (.005" base poly­ester with .002" of acrylic adhesive on each side).

Pre-testing of all switches is performed by following these steps:

1) 24-hour immersion in a solution of water with .2% by volume of soap added.

2) Insulation resistance readings are then taken on each switch at 100 VDC. A minimum of 1 mO insulation resistance is required for each switch to enter the testing phase.

• HeatSeal spacer - no visual degradation of the switch occurred in any of the switches. There were no measurable changes in the insulation resist­ance of any of the parts (see Figure 12).

• Pressure sensitive acrylic spacer - results varied with each solution:

1) 409 - ingression and dissolving of the PSA adhesive occurred uniformly around the perimeter of the switch. 1st failure of insulation resistance occurred on day 20 (Figures 13 and 14).

2) Fantastik - ingression and dissolving occurred as above. Failure occurred on day 42 (see Figure 15).

3) Dow Bathroom Cleaner - ingression and dissolving occurred as above. Failure occurred on day 56 (Figure 15).

4) Lysol Tub and Tile Cleaner - ingression and dissolving occurred as above. Failure occurred on day 92 (see Figure 15).

Eight beakers are each filled 3/4 full with a cleaning solution and four drops of green dye. The cleaning solutions are:

A) 409®

B) Fantastik®

C) Dow^® Bathroom Cleaner^®

D) Lysol^® Tub and Tile Cleaner^®

Samples of each switch type are immersed in each of the four solu­tions. Each group of parts are then placed in an airtight container, to reduce evaporation, for a period of 180 days at room temperature.

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