Solderable Case Study
Sealing a Liquid Crystal Display:
Dan Cousen at Coursen Coating Labs.,
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[Type a quote from the document or the summary of an interesting point.
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
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.