Case Studies

Example of improving dimensional accuracy with a zirconia plate of low thermal expansion and thickness tolerance of +/-10 micrometers.

Overview

The hot-pressing machine is used to produce multilayered components with the thermal-compression-bonding method. Multilayered components require very accurate dimensional control in a vertical direction. To achieve this accuracy, it is essential to apply pressure evenly over the components without any deterioration of the tooling surface at a high temperature of 400 degrees Celsius.

Challenge

Deterioration of dimensional accuracy caused by thermal expansion of holders

A thermal insulator made of a cement material was conventionally used for the tooling holders. However, there was a deformation issue of the lower punch caused by thermal expansion of the supporting holder with an embedded heater whose temperature reached up to 400 degrees Celsius. The deformation of the lower punch resulted in larger thickness variation of the components and poor yield.

Conditions
・Low thermal expansion at high temperature of 400 degrees Celsius
・Low thermal conductivity to insulate the entire machine from the embedded heater
・High hardness and stiffness as the tooling holder

Solution

Use ceramics with low heat expansion in mountings

We used zirconia with its lower heat expansion compared to conventional thermally insulating cement material.
The zirconia was worked at a high degree of accuracy to a set plate shape (thickness accuracy ±0.01mm), and installed as mountings for the molds (heat conductivity, hardness, and strength tolerances checked with samples).

Result

Success in reducing deformation of holders

By reducing thermal expansion of the tooling holder, we significantly improved accuracy of the tooling punch. This enabled the client to produce multilayered components of higher dimensional accuracy than before.

*Structures in the pictures and animation have been simplified.
*Material property can change depending on operating conditions.

Case Studies