Advanced Materials for Electronics

Ohmex – AG

Thermosetting Silver for Ohmic Bonding to Semiconductors

Produces Quality Electrical and Mechanical Contacts


  • One – part system
  • High bond strength
  • Ohmic contacts
  • Low contact resistance
  • Low thermal impedance
  • Low thermal stress
  • Temperature Stability -65 °C to +275 °C
  • Low outgassing


CHIP BONDING – Silicon, germanium and other semiconductor materials – for transistors, diodes, rectifiers, thermistors, integrated monolithic and hybrid circuits. Also bonds to: glass, metals, ceramic, mica, plastics, graphite, and quartz



Ohmex-Ag is a conductive silver preparation containing as a bonding constituent silver epoxide. It is supplied in the form of a thin paste, ready to use. Its composition is unique, providing high conductivity and excellent bonding strength after appropriate cure. OHMEX-Ag is used to advantage in place of lead-tin solder or other alloys to avoid flux contamination or exposure to excessive temperature and for process simplification. OHMEX-Ag produces very low resistance ohmic contacts with all metals and bonds as well to most insulators. Ohmic bonds are also produced with semiconductors if the surface is first metallized or if the surface is highly “doped” and lapped. OHMEX-Ag finds extensive use in bonding semiconductor chips, integrated monolithic and hybrid circuits, diodes and transistors, and thin films on ceramic substrates – in all types of package configurations.


System One-Part
Composition Silver filled epoxy
Density 2.5 g/cc
Viscosity 90,000 cps.
Electrical Resistivity, Nominal 5 x 10-4 ohm-cm
Thermal Conductivity 100 BTU/ft2/hr./°F./in.
Outgassing 0.097% @ 100 °C (1250 hours)
0.7% @ 125 °C (1000 hours)
< 1.2% @ 160 °C (1000 hours)
Bond Shear Strength > 1000 PSI
Temperature Stability Range -65 °C to + 275 °C ( +325 °C intermittent)
Linear Coef. of Therm Expan. 5 x 10-5 cm/cm/°C
Storage 40 °F or below
Shelf Life 6 months
Thinner Butyl cellosolve acetate
Cure Temp. 150 °C (minimum)


Use OHMEX-Ag as supplied. Special thinner is supplied though thinning is unnecessary for most application. Apply OHMEX-Ag to the parts to be bonded, press lightly, then cure in drying over at 150° – 160 °C for at least 15 hours or 1 hour at 150 °C followed by at least 1 hour at 265 °C.

Special Thinner available