Ceramic Multilayer Substrate Stacking for Sintering Shrinkage Control

Solution Overview

Problem

Conventional methods for producing ceramic multilayer substrates face challenges in managing sintering shrinkage, which can lead to stress, cracks, and deformation of integrated redistribution traces, increasing the risk of unusable components and requiring additional laborious and costly post-sintering processing.

Innovation Solution

A method involving alternating stacking sequences of green sheets with varying sintering aid concentrations, where first green sheets with lower sintering shrinkage counteract the higher shrinkage of second green sheets, reducing overall sintering shrinkage to less than 16% in each spatial direction, and incorporating a ceramic material like AlN for improved thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional methods use green sheets with sintering aids to produce ceramic multilayer substrates, then the substrates can be formed with integrated redistribution traces, but great sintering shrinkage occurs causing stresses and cracks in the ceramic main body

Engineering Contradiction:

Improveability to form ceramic multilayer substrates with integrated redistribution tracesVSAvoidformation of cracks in ceramic main body

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The green sheet stack is segmented into alternating first green sheets (without sintering aids) and second green sheets (with sintering aids). This segmentation allows different regions to have different sintering shrinkage characteristics, with the first green sheets counteracting the shrinkage of the second green sheets, thereby reducing overall sintering shrinkage and preventing cracks while still enabling integrated redistribution traces to be formed in the second green sheets.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different green sheets are assigned different local qualities: the first green sheets have no sintering aids and exhibit low sintering shrinkage, while the second green sheets contain sintering aids and exhibit high sintering shrinkage. This local differentiation allows the stack to achieve both crack prevention (from first green sheets) and trace integration (in second green sheets).

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If green sheets with sintering aids are used to enable trace integration, then redistribution traces can be incorporated into the ceramic main body, but the sintering shrinkage causes deformation or tearing of the integrated redistribution traces

Engineering Contradiction:

Improveintegration of redistribution traces into ceramic main bodyVSAvoiddeformation or tearing of redistribution traces

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The green sheet stack is segmented into alternating first green sheets (without sintering aids) and second green sheets (with sintering aids). This segmentation allows different regions to have different sintering shrinkage characteristics, with the first green sheets counteracting the shrinkage of the second green sheets, thereby reducing overall sintering shrinkage and preventing cracks while still enabling integrated redistribution traces to be formed in the second green sheets.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sintering shrinkage parameter is changed by alternating green sheets with and without sintering aids. The first green sheets have low shrinkage parameters that counterbalance the high shrinkage parameters of the second green sheets containing sintering aids and traces, thereby preserving trace integrity while enabling integration.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If uniform green sheets with sintering aids are used throughout the stack, then trace integration is enabled, but great sintering shrinkage occurs in all three spatial directions causing stresses and potential cracking

Engineering Contradiction:

Improveintegration capability of substrateVSAvoidstress resistance of ceramic main body

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The green sheet stack is segmented into alternating first green sheets (without sintering aids) and second green sheets (with sintering aids). This segmentation allows different regions to have different sintering shrinkage characteristics, with the first green sheets counteracting the shrinkage of the second green sheets, thereby reducing overall sintering shrinkage and preventing cracks while still enabling integrated redistribution traces to be formed in the second green sheets.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first green sheets act as a counterweight to the sintering shrinkage of the second green sheets. By alternating these sheets, the low-shrinkage first green sheets compensate for and counterbalance the high-shrinkage second green sheets, reducing net shrinkage and preventing stress-induced cracking while maintaining trace integration capability.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

4Reliability

If post-sintering processing is performed to remove sintering aid enrichment on surfaces, then component reliability is improved, but additional labor and cost are incurred

Engineering Contradiction:

Improveoperational reliability of componentsVSAvoidproduction complexity and cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The green sheet stack is configured with alternating first green sheets (without sintering aids) and second green sheets (with sintering aids) before sintering. The first green sheets positioned at the surfaces act as a barrier during sintering, preventing sintering aid enrichment on the outer surfaces. This preliminary configuration eliminates the need for post-sintering removal processing while ensuring component reliability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The sintering aids that would normally cause harmful enrichment on surfaces are instead placed in internal second green sheets, where their shrinkage is counteracted by surrounding first green sheets. The harmful surface enrichment is converted into a beneficial internal structure that maintains reliability without requiring additional processing.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves reduced sintering shrinkage, enhanced robustness with a transverse rupture strength of at least 450 MPa, and allows for compact design with integrated redistribution traces, supporting further miniaturization and reliable component operation.

Implementation Method 1

Subsequent sintering of the pressed and decarburized green sheet stack produces the ceramic main body of the multilayer substrate

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

a sintering shrinkage that occurs during the sintering of the green sheet stack

Methodology Applied

Scientific EffectSintering shrinkage: Thermal Contraction

Data Source

PatentUS12441088B2Substrate and method for producing the substrate

Publication Date: 2025.10.14 TDK ELECTRONICS AG

AI summary

In an embodiment a method for producing a substrate includes forming a green sheet stack including first green sheets and second green sheets, wherein each of the first green sheets and the second green sheets contains a ceramic material as a main component, and wherein the second green sheets further contain a sintering aid in addition to the ceramic material.