Coursen Coating Labs Inc.

2925 College Ave. # A1

Costa Mesa, CA 92626

PH: (714)-585-4172  Fax: (657)-247-4296

Solderable Case Study
Sealing a Liquid Crystal Display:
Customer's Problem

An exceptionally non-contaminating hermetic seal was needed to seal the fill hole of a liquid crystal

device. Epoxies and other resins either polluted the liquid crystal or failed to bond perfectly to the

glass. They all allowed the migration of water into.



Failure Mode

Virtually all organic resins will slowly transmit moisture either by capillary action or chemical

transfer. When the sealed volume is very small, the amount of water needed to destroy the device is

incredibly small.



Coursen Coating Labs Solution

The area around the fill hole was coated with a platinum solderable system, type 2LPT. The parts

were sent to coating after assembly firing with no further cleaning required. The filled parts were

soldered in air with 60-40 lead tin solder, using no flux. The trace of liquid crystal fluid near the

hole acted as a flux.



Case Study Results

The customer reported that out of 1.5 million parts, 200 failures were found during the solder

operation. No life failures were reported, even in water immersion tests.