Hybrid microelectronics relay has characteristics significantly superior to conventional solid state relays. Relay provides 2500 Vdc input to output isolation and operates from high threshold logic signal to switch load of 400 Vdc at 2 mA. Technology should be of interest to manufacturers of discrete components

Janssen, W. A.

Riley, T. J.

Sater, B. L.

English

NASA Technical Reports Server

rire 2. - Fligti Voltae Ri'lav 
March 1974	 B74-10006 
• 
NASA TECH BRIEF 
Lewis Research Center 
NASA Tech Briefs announce new technology derived from the U.S space program. They are issued to encourage 
commercial application Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151 Requests for individual copes or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C.20546. 
High Voltage Solid-State Relay 
Leakage at	 Temperature	 Voltage 
Corona Inception	 1000 V	 Range	 Isolation 
Conventional relay	 1400-1800 volts	 10 pA	 218 to 398 K	 1000 Vrms 
(-67 to 2570F) 
High voltage relay	 5500-6000 volts	 <.001 pA	 153 to 353 K	 2500 Vdc 
(-184 to 1760F) 
Figure 1 
A hybrid microelectronics solid state relay has been 
developed which has characteristics that are significantly 
superior to conventional solid state relays (Figure 1). The 
relay was developed for a space flight project to measure 
the effects of space plasma on exposed high voltage 
systems and to evaluate edge-illuminated multijunction 
solar cells. The relay provides 2500 Vdc input to output 
isolation and operates from a high threshold logic signal to 
switch a load of 400 Vdc at 2 mA. The relay was designed 
to operate in outer space and survive 1000 thermal cycles 
of 153 to 353 K (-184 to 176'F). Conventional relay 
design was advanced to achieve these characteristics. 
For this project, the conventional design was simplified 
since the relay interfaced with the logic output of a high 
threshold logic gate where the "one" would be greater 
than 10 V but lImited to the 15 V supply from which the 
gate is operated. The use of the high threshold logic gate 
allowed the input threshold to be raised to 10 V for noise 
immunity and eliminated the need for a snap action 
trigger circuit, therefore simplifying the output circuitry 
to a rectifier, filter and transistor switch. For high voltage 
isolation, all input circuitry was located on the input 
substrate and all output circuitry was located on the 
output substrate (Figure 2). The transformer windings 
were separated, a larger transformer core was used to 
increase physical separation of the windings and reduce 
the number of turns required (thereby maximizing 
possible isolation), and the transformer located between 
the input and output substrates. The substrates were 
designed to eliminate any unused leads in order to 
minimize leakage paths and allow room for proper 
positioning of the transformer. Higher voltage wire and 
welded leads, rather than soldered leads, were used to 
reduce leakage associated with substrate contamination by 
flux.
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Encapsulation was used in order to hold the leads in 
place during handling as well as to pin down loose 
particles that could destroy the device internally during 
vibration. The relay interior was coated with a high 
dielectric strength, clean, relatively thin film polymer that 
would survive the operating environment. A vacuum 
deposited para-xylylene polymer was used as the encap-
sulant. The coating thickness and rate of deposit were 
controlled to build up as little as 0.007 mils or as great as 
1 mil per minute. This polymer has a dielectric breakdown 
voltage of 5600 V/mil and can be deposited thin enough 
that it will not cause destructive physical stresses but will 
be dielectrically strong enough to provide the necessary 
voltage isolation. The transformer core was also coated 
prior to winding in order to give it better isolation. 
Thermal cycling tests from 153 to 353 K(-184 to 176°F) 
appeared to be stress free, primarily because the polymer 
was applied in uniformly thin applications. 
Notes: 
1. This technology should be of interest to manu-
factureres of discrete components such as: computer-
power interfaces, computer-teletype interfaces, isolated 
line drivers, isolated analog signal relays, sensor 
actuated relays, controllers and isolated multiplex 
relays. 
2. Further information is available in the following 
report: 
NASA TM-X-68248 (N73-24235), Development of 
a Hybrid Microelectronics Solid State Relay for 
2500 Volts Isolation and -120°C to 80°C Thermal 
Cycling Range 
Copies may be obtained at cost from: 
Aerospace Research Applications Center 
Indiana University 
400 East Seventh Street 
Bloomington, Indiana 47401 
Telephone: 812-337-7833 
Reference: B74-10006 
3. Specific technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B74-10006 
Patent Status: 
NASA has decided not to apply for a patent. 
Source: B.L. Sater and T.J. Riley

Lewis Research Center,
and W.A. Janssen
Sterer Eng. & Mfg. Co.

(LEW-1 2096)
S 
B74-10006	 Category 01


High voltage solid-state relay

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