Silicon Nitride Bonded Substrate Structure for Stronger Copper Adhesion
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Solution Overview
Problem
Conventional bonded substrates with silicon nitride ceramic substrates face issues with insufficient adhesion strength of the bonding layer, leading to poor cold durability and potential ion migration when a voltage is applied.
Innovation Solution
Incorporating penetrating regions with penetrating portions that penetrate into the silicon nitride ceramic substrate, each 3 µm to 20 µm deep, and limiting their number to 1 to 30 per square millimeter, along with patterning the copper and bonding layers, enhances adhesion and reduces ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal substrate is used to ensure strength and heat dissipation, then mechanical strength and thermal conductivity are improved, but electrostatic charging occurs during manufacturing processes causing defects
Solution Approach 1:
The patent uses a composite substrate structure consisting of a metal substrate layer combined with a resin layer. The metal substrate provides the necessary mechanical strength and heat dissipation, while the resin layer acts as an electrostatic dissipation layer that prevents electrostatic charging during manufacturing. This composite structure resolves the contradiction by combining materials with complementary properties.
2Object-affected harmful factors
If a resin substrate is used to prevent electrostatic charging, then electrostatic issues are resolved, but heat dissipation capability deteriorates
Solution Approach 1:
The patent employs a composite substrate where a metal substrate layer (providing heat dissipation) is combined with a resin layer (providing electrostatic dissipation). The metal layer ensures adequate thermal conductivity while the resin layer prevents electrostatic charging, thus resolving the contradiction between electrostatic performance and heat dissipation capability.
3Strength
If adhesive amount is increased to improve bonding strength, then bonding between layers is improved, but resin protrusion and appearance defects occur
Solution Approach 1:
The patent optimizes the adhesive amount to a specific range (0.5-2.0 mg per bonding area) to achieve adequate bonding strength while preventing resin protrusion. This parameter optimization resolves the contradiction by finding the precise amount of adhesive that provides sufficient bonding without causing appearance defects.
Solution Approach 2:
The patent introduces a resin layer as an intermediary between the metal substrate and the display elements. This resin layer serves multiple functions: it provides electrostatic dissipation, acts as a bonding interface with controlled adhesive amount, and prevents direct contact that would cause appearance defects, thus mediating between bonding requirements and appearance 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 solution improves adhesion strength, resulting in a bonded substrate with high cold durability and maintained insulation resistance, suppressing ion migration and ensuring reliable performance under electrical stress.
Implementation Method 1
ITO (indium tin oxide) layer that has electrostatic dissipation capability
Implementation Method 2
an adhesive layer formed between the first substrate and the second substrate
Data Source
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AI summary
An adhesion strength of a bonding layer to a silicon nitride ceramic substrate is improved, and a bonded substrate which has high cold durability and in which migration does not occur is obtained. The bonded substrate includes the silicon nitride ceramic substrate, a copper plate, the bonding layer, and penetrating regions. The copper plate and the bonding layer are patterned into a predetermined shape, and are disposed over a main surface of the silicon nitride ceramic substrate. The bonding layer bonds the copper plate to the main surface of the silicon nitride ceramic substrate. The penetrating regions each include one or more penetrating portions penetrating continuously from the main surface of the substrate into the silicon nitride ceramic substrate to a depth of 3 µm or more and 20 µm or less, and contain silver, and the number of penetrating regions present per square millimeter of the main surface of the substrate is one or more and 30 or less.