Insulating Substrate Ni Plating Layout for Heat Cycle Resistance

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Solution Overview

Problem

Existing insulating substrates for semiconductor power modules suffer from inadequate furnace passing resistance and heat cycle characteristics, particularly when a heat sink plate is soldered, leading to ceramic substrate cracking due to solder-induced brazing material layer dissolution and brittle compound formation.

Innovation Solution

Incorporating a Ni plating layer to cover the brazing material layer exposed between the ceramic substrate and the heat-dissipation-side metal plate, while leaving at least a portion of the metal plate surface uncoated, prevents solder components from diffusing into the brazing material, thereby inhibiting crack formation and maintaining heat dissipation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the entire copper plate is coated with Ni plating to improve corrosion resistance and soldering, then corrosion resistance and soldering are improved, but the brazing material layer becomes exposed and vulnerable to solder-induced dissolution and brittle compound formation

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidsolder-induced brazing material layer dissolution

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies Ni plating selectively to specific regions of the copper plate rather than the entire surface. The Ni plating is applied to the circuit pattern area to provide corrosion resistance and improve soldering, while deliberately leaving the brazing material layer exposure area unplated to prevent solder from causing brazing material layer dissolution and brittle compound formation.

Inventive Principle:

Principle #3Local quality

2Temperature

If a thick heat sink plate is soldered to the heat-dissipation-side metal plate to improve heat dissipation, then thermal conductivity is improved, but the ceramic substrate becomes susceptible to cracking under heat cycle conditions

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidcrack resistance of ceramic substrate

Core Design Contradiction:

TemperatureVSStrength

Solution Approach 1:

The patent introduces an intermediate protective structure consisting of the heat-dissipation-side metal plate bonded to the ceramic substrate via a brazing material layer. This intermediate layer acts as a stress buffer that absorbs thermal expansion differences between the ceramic substrate and the thick heat sink plate, preventing direct stress transmission that would cause ceramic cracking during heat cycles.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If the insulating substrate is designed with exposed brazing material layer to ensure thermal conductivity, then heat dissipation is improved, but the brazing material layer becomes vulnerable to solder component diffusion

Engineering Contradiction:

Improvethermal conductivityVSAvoidbrazing material layer composition stability

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent applies different surface treatments to different regions of the metal plate. The brazing material layer exposure area is deliberately left without Ni plating to maintain thermal conductivity and ensure proper brazing, while the circuit pattern area receives Ni plating to prevent solder component diffusion into the brazing material layer.

Inventive Principle:

Principle #3Local quality

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 insulating substrate achieves enhanced furnace passing resistance and improved heat cycle characteristics by preventing solder-induced brazing material dissolution, ensuring reliable operation under high thermal stress.

Implementation Method 1

a Ni plating layer that covers the brazing material layer exposed between the ceramic substrate and the heat-dissipation-side metal plate

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

one principal surface of a heat-dissipation-side metal plate is brazed to one principal surface of a ceramic substrate via a brazing material layer provided therebetween

Methodology Applied

Scientific EffectBrazing: Brazing

Data Source

PatentUS12610816B2Insulating substrate and manufacturing method thereof

Publication Date: 2026.04.21 DOWA METALTECH CO LTD

AI summary

An insulating substrate in which one principal surface of a heat-dissipation-side metal plate is brazed to one principal surface of a ceramic substrate via a brazing material layer provided therebetween, in which a Ni plating layer that covers the brazing material layer exposed between the ceramic substrate and the heat-dissipation-side metal plate is provided, and at least a portion of the other principal surface of the heat-dissipation-side metal plate is not covered with a Ni plating layer, leaving the surface of the heat-dissipation-side metal plate exposed. According to the present invention, it becomes possible to obtain the insulating substrate having excellent furnace passing resistance of the insulating substrate (alone) and further having excellent heat cycle characteristics in a state of a heat sink plate being soldered to the insulating substrate.