Testing Methods

ASTM-D5470-06: Lab controlled thermal resistance tester used for determining TIM bulk thermal conductivity (W/mK).

This is a steady state method of determining the thermal conductivity of a substance. The thermal resistance (more specifically eferred to as thermal impedance) for a material, at a given thickness, is determined by placing the paste at the interface between equilibrated hot and cold blocks. The heat flow though the material is determined by the measuring the temperature gradient set up between the two blocks at steady state. The temperatures are determined at set placements along the hot and cold gradients as shown in the following figure of an actual trace obtained on an ASTM D-5470-06 flow apparatus hee at AOS.

 

 


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Thermal conductivity

for a material is determined (back calculation) by determining the inverse of the slope of the graph of several thermal impedances (resistances) at various thicknesses. The graph below shows the results taken at 1, 2, 5 and 20 mils (0.001” = mil).

 

 

 

 

 

 

AOS Thermal Compounds does internal thermal testing as well as outside third party testing to confirm esults. We are also pleased to offer thermal testing services, including TIM life cycle testing.

 

 

 

Testing Methods

ORACLE® 270-7806-01 TTV:

In situ thermal resistance tester for determining comparative TIM thermal performance in “real world” integrated circuits.

The Thermal Test Vehicle (TTV) is used to provide a thermal resistance on a device that is closer to real-world applications. It consists of a ca. 1” x 1” bare silicone die and a copper heat sink. The copper heat sink has an embedded T type thermocouple that measures the temperature of the heat sink. The silicone die has 34 thermal sensors across the area of a die that measure the resistances in response to the build up of heat. 0.5 grams of thermal grease is applied between the die and heat sink and a uniform power is supplied across the die. The resistances of an area on the die and the heat sink temperature are recorded after the power is applied and temperature equilibrium is established. The temperatures and resistances are recorded in an Excel file as shown.

 

 

 

The average temperature of a specific aea on the die corresponding to an average resistance measurement is determined using a calibration chart. The chart is developed from die resistances recorded at a number of set temperatures as shown below.

The power supplied to the TTV is carefully recorded also. The resistance is determined using the fundamental equation (Tr –Ths)/ P