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the Bergquist advantage HeatSeal Holds Up Under Pressure PSA SWITCHESHEATSEAL SWITCHES Typical air distribution with-in a pressure sensitive adhesive
(PSA) membrane switch at time
of manufacture is shown in
Figure3.The buildup of air pressuredifferential as the membrane
switch is raised to an elevation of
40,000 feet is shown in Figure 4.The air pressure within theswitch becomes great enough to
force its way through the micro
fissures in the PSAuntil the air
pressures between the switch andthe environment have equalized.The resulting distribution ofair within the switch once it has
returned to a normal elevation is
shown in Figure 5.The memory within thepolyester does not have enough
force to draw air back into the
switch cavities. The end result is
collapsed, electrically shorted
switches.
Figure 6 depicts the typicaldistribution of air within a
HeatSeal membrane switch at
time of manufacture.The buildup of air pressuredifferential as the HeatSeal switch
is raised to an elevation of 40,000
feet is shown in Figure 7.The air pressure buildup willincrease the actuation force of the
switch at elevation. However, the
force of the air pressure cannot
overcome the bond strength of
HeatSeal.
The resulting, unaffecteddistribution of air within the
HeatSeal membrane switch once
it has returned to normal elevation
is shown in Figure 8. These illustrations show the overall
protection strength of Bergquist
HeatSeal.HeatSeal’s strength and
impenetrable lamination protects
the delicate switch circuitry from
harsh environments,solvent attack,
fluid ingression and electrostatic
discharge (ESD). 10X microscopic view of PSA material shows air gaps inherent in the natureof the material,thus making it susceptible to leakage under higher or lower
air pressure.10X microscopic view of HeatSeal material shows solid nature of the material,thus making it impervious to leakage under higher or lower air pressure. FIGURE 3: PSA Switch - Air Pressure @ Equilibrium FIGURE 6: HeatSeal Switch - Air Pressure @ Equilibrium FIGURE 4: PSA Switch - Air Pressure @ Higher Altitude FIGURE 7: HeatSeal Switch - Air Pressure @ Higher Altitude FIGURE 5: PSA Switch - Air Pressure @ Normal Altitude FIGURE 8: HeatSeal Switch - Air Pressure @ Normal Altitude 3
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