Conventionally, high-lead solder is widely used in power semiconductors due to its high connection reliability among solder materials. However, its thermal conductivity is lower than those of other component materials, resulting in a challenging bottleneck issue during heat dissipation. In contrast to a general high-lead solder with 30W/(m･K) of thermal conductivity, our sintered copper die-bonding paste has an increased thermal conductivity (180W/(m･K)), to be used as an ideal die-bonding material to overcome the temperature increase in power semiconductors.

Die-bonding with high-lead solder has the problem that the die-bonding layer suffers fatigue fractures due to the stress caused by the difference in the thermal expansion of parts, resulting in the connection of semiconductor chips not being operating adequately. During the power cycle test (T_j.max= 175℃) it has been proved that our sintered copper die-bonding paste ensures a higher number of cycles than high-lead solder and sintered silver, has good durability, and can maintain the connection reliability of semiconductor chips.

The product has a high thermal conductivity 180 W/(m･K), which is five or more times that of high-lead solder 30 W/(m･K) and is most suitable as a die-bonding material for semiconductor chips that are subject to the highest thermal load among power semiconductors.

Our lineup of sintered copper die-bonding paste consists of two types: a “non-pressure bonding type” that does not require thermal compression pressure (required gas atmosphere: hydrogen) and a “pressure bonding type” that allows for bonding with 2 MPa or less of thermal compression pressure. Compared to sintered silver paste, which is a die-bonding material also having high thermal conductivity and a thermal compression pressure of 20 MPa, our product allow for bonding with one-tenth of that pressure. Therefore, a contribution to the improvement in the yield rate during semiconductor chip mounting is expected.

A maximum of 90W/(m･K)thermal conductivity is achieved by orienting high thermal conductive graphite filler in the vertical direction. The thermal conductivity of this product, which is about 18 times that (5W/(m･K)) of grease thermal interface materials (TIMs), allows for quick heat dissipation to radiating parts such as heat sinks, reducing temperature increase in semiconductors and contributing to ensure semiconductor chip performance.

The use of grease thermal interface materials (TIMs) raises the problem that grease is forced out due to the thermal deformation of power semiconductors and voids generate in the grease (pump-out), thereby increasing thermal resistance and resulting in insufficient heat dissipation. The use of a sheet of thermal interface material (TIM) can avoid the occurrence of pump-out and increase endurance reliability.

Forming vertically oriented graphite filler in sheets results in excellent thermal conductivity in the vertical direction. A maximum of 90 W/(m･K) is achieved when the product is in bulk form, and a maximum of 45 W/(m･K) is achieved when it is in practical use.

Delamination between molding compounds and substrates is caused by the difference in thermal stress among power semiconductor component materials. “HIMAL” <HL-1210G2>with a linear expansion coefficient of about 60 ppm and an elastic modulus of 2.6 GPa is more flexible compared to molding compounds, semiconductor chips and lead frame metals. Therefore the material can reduce the stress caused during temperature increase in manufacturing processing and prevent delamination in semiconductor packages.

The sizes of power semiconductor packages handling 1700 V or more of higher voltages have been increasing to ensure insulation performance. “HIMAL” has a high break down voltage of 230V/μm or more and it achieves partial insulation performance without upsizing packages.

Even under severe temperature environments HIMAL can reduce the stress caused between component materials by preventing delamination due to the high heat resistance and adhesive strength. Therefore the temperature of the thermal cycle test (TCT) which is conventionally carried out between -40℃ and 125℃, can be increased up to 175℃. Furthermore the power cycle test (PCT) indicating the power cycle lifetime can nearly be doubled*.