Semiconductor Junction Coating
Silicone Elastomer Systems for Protection and Passivation of Semiconductor Junctions

Translastic Semiconductor Junction Coatings, Types 3811 and 3812, are high purity, 100% solids, siloxane systems designed for passivation coating transistor, diode and rectifier junctions. Demanding production procedures and rigid quality control requirements guarantee ionic purity levels of 1 ppm (maximum). Typical applications include conformal coatings to provide mechanical and electrical insulation prior to plastic molding; protective coatings over hybrid integrated circuits to prevent chip damage during potting; and other ultra-pure, hermetic-type passivations.

Type 3811 and 3812 Junction Coatings will prevent electrical breakdown, minimize junction surface leakage, stabilize peak inverse voltage, and provide environmental protection for high temperature performance and thermal cycling.

PROPERTIES

TYPE 3811

TYPE 3812

System

One-Part

Two-part

Solids

100%

100%

Appearance

Clear

Clear

Viscosity

7,500 cps

5,000 cps

Shelf Life

3 months

12 months

Storage Temperature

40 °F or below

Room Temperature

Specific Gravity

1.03

1.03

Mix Ratio

------

10 to 1

Pot Life

------

> 48 hours

Durometer (shore A)

30

30

Tensile Strength (psi)

400

350

Elongation (%)

130

140

Dielectric Strength

> 450

> 450

Dielectric Constant @ 106 Hz

3.50

3.50

Volume Resistivity ohm/cm

1015

1015

Dissipation Factor @ Imc

0.001

0.001



METALLIC IMPURITY (by spectographic analysis)

Metal

ppm Max.

Metal

ppm Max.

Aluminum (Al)

1.0

Lead (Pb)

1.0

Antimony (Sb)

1.0

Magnesium (Mg)

1.0

Chromium (Cr)

1.0

Nickel (Ni)

1.0

Copper (Cu)

1.0

Potassium (K)

1.0

Iron (Fe)

1.0

Sodium (Na)

1.0



CURE:
Electrical performance of junctions coated with these elastomers is influenced by both temperature and duration of cure. Longer post-cures and higher temperatures generally improve device characteristics.

CURE SCHEDULE:
1/2 hour @ 80 °C + (optional)
1 hour @ 135 °- 150 °C (cure)
2 hours @ 200 °-225 °C (post cure-minimum)


Semiconductor Junction Coating - Type I

Low cost, heat stable, moisture resistant, high purity silicone resin for semiconductor applications. Designed specifically for environmental protection of transistors, diodes and rectifiers.

PHYSICAL PROPERTIES:

System

One-part; rigid

Base

Silicone resins

Appearance

Light amber

Specific Gravity

1.03

Viscosity

350 cps

Flash Point

90°F

Thinner

Xylene

Solids

50%

Shelf Life

5 months @ 25°C

Thermal Life 250°C

> 10,000 hours



CHEMICAL SPECIFICATIONS:

Sodium

< 1 ppm

Potassium

< 1 ppm



ELECTRICAL:

Dielectric Strength

> 2500 (v/mil)

Dielectric Constant

2.75 (1 mc)

Volume Resistivity

> 1016 ohm-cm

Dissipation Factor

0.001 (1 mc)


APPLICATION:

Dip, paint, spray or transfer.

CURE:

Air dry for 20 minutes. Bake at 65°C for 20 minutes, then at 125° for 1/2 hour. Postcure at 225°C for 1/2 hour, or at 200°C for 5 hours.