Sputtering Target Bonding Process Center-First Heating
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Solution Overview
Problem
Conventional processes for producing sputtering targets face challenges in achieving high bonding strength between the target material and the backing plate material, particularly at the center part, due to uneven pressure distribution and air gaps, which affects the efficiency and cost of the hot isotropic pressing process.
Innovation Solution
A process where the target material is diffusion-bonded to a backing plate using a hot press, with the top face of the target material being heated at the center part prior to the outer peripheral part, allowing for increased bonding strength by applying load from the center to the periphery and eliminating air gaps, thereby enhancing the bonding strength to 7 kg/mm2 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot isostatic pressing is applied to diffusion-bond target material to backing plate material, then bonding is achieved, but bonding strength at the center part is insufficient
Solution Approach 1:
The patent applies local quality by creating a convex portion on the pressing surface that concentrates pressing force specifically on the center part of the target material. This localizes the high-pressure zone to where it is most needed (the center), while the peripheral areas receive appropriate but less intensive pressure, thereby achieving uniform bonding strength distribution across the entire bonding surface.
Solution Approach 2:
The patent introduces asymmetry by designing a non-uniform pressing surface with a convex portion rather than a flat surface. This asymmetric geometry allows differential pressure distribution, with higher pressure at the center and gradually decreasing pressure toward the periphery, which compensates for the natural pressure decay in hot isostatic pressing and achieves uniform bonding strength.
2Ease of manufacture
If uniform pressing is applied during diffusion-bonding, then the process is simple, but air gaps remain between target material and backing plate
Solution Approach 1:
The convex portion on the pressing surface creates a localized high-pressure zone that specifically targets the center area where air gaps are most likely to form. This local quality enhancement allows the process to remain relatively simple while effectively eliminating air gaps through concentrated pressure application where needed most.
3Strength
If high pressure is applied to achieve high bonding strength, then bonding strength increases, but required pressure and time increase
Solution Approach 1:
By concentrating pressing force through the convex portion on the pressing surface, the patent achieves high bonding strength with lower overall pressure requirements. The localized pressure concentration allows effective bonding without subjecting the entire system to high pressure, thereby reducing the power and time requirements while maintaining high bonding strength at 7 kg/mm² or more.
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
This process increases the bonding strength between the target material and the backing plate material, reduces the required pressure and time for bonding, and lowers costs compared to traditional hot isotropic pressing methods, while maintaining the integrity of the target material.
Implementation Method 1
heating a top face of the target material by a hot plate at a center part of the face prior to an outer peripheral part of the face
Implementation Method 2
pressing from above to perform diffusion-bonding the target material to the backing plate material
Data Source
AI summary
A process for producing a sputtering target in which a target material is diffusion-bonded to a top face of a backing plate material, the process comprising:a step of heating the top face of the target material by a hot plate while pressing from above thereby diffusion-bonding the target material to the backing plate material in such a manner that the step is performed at a center part prior to an outer peripheral part of the top face.