Hermetic Package Sealing With Localized Pressure to Cut Bonding Load
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Solution Overview
Problem
In wafer-level packaging, achieving a balance between pressurization force and sealing quality is challenging, as excessive force can exceed the capacity of bonding devices, while insufficient force may lead to voids and leaks, especially when multiple sealing regions are present on a substrate.
Innovation Solution
A method using a protruding projection with a width smaller than the sealing material on a substrate to apply unidirectional pressure, ensuring densification of the metal powder sintered body without voids, thereby reducing the overall pressing load required for hermetic sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressurizing force is increased to densify the sealing material and eliminate voids, then sealing quality improves, but the pressing load on the substrate and bonding device increases excessively
Solution Approach 1:
The patent applies local quality by introducing a protruding projection that concentrates pressurizing force specifically at the sealing material region. The projection has a width smaller than the sealing material width, creating a localized high-pressure zone that densifies the sealing material and eliminates voids without requiring excessive overall pressing load on the substrate
Solution Approach 2:
The protruding projection acts as an intermediary element between the upper substrate and the sealing material. It mediates the force transmission by concentrating pressure at the sealing interface, enabling effective densification of the sealing material while reducing the total load that must be applied to the entire substrate assembly
2Ease of manufacture
If pressurizing force is decreased to reduce pressing load on the bonding device, then device capacity requirements are reduced, but voids remain in the sealing material causing leaks
Solution Approach 1:
By using a protruding projection with width smaller than the sealing material, the patent creates a localized pressure concentration effect. This allows the bonding device to operate at lower overall force levels while still achieving sufficient densification at the critical sealing interface, thereby eliminating voids and preventing leaks
3Productivity
If the number of sealing regions on the substrate increases, then packaging productivity improves, but the total pressing load required for densification increases proportionally
Solution Approach 1:
The protruding projection enables localized force application at each sealing region. When multiple sealing regions are present on a substrate, each region benefits from concentrated pressure through its corresponding projection, allowing densification to be achieved with lower overall pressing load compared to uniform pressure distribution across the entire substrate surface
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 approach allows for reliable hermetic sealing with a lower pressurizing force, reducing the load on the substrate and preventing voids, while maintaining high airtightness in the sealing regions, even with multiple sealing regions on a substrate.
Implementation Method 1
the sealing material is pressurized to be densified to the extent that the sealing material is almost as dense as a bulk body
Implementation Method 2
A protruding projection (core material) having a width smaller than that of the sealing material is provided on a substrate... contact surface between the core material and the sealing material is preferentially pressurized
Data Source
Figure 1~2(c)
Figure 3~3(d)
Figure 4~5
AI summary
The present invention relates to a package production method includes the step of superposing a pair of substrates on each other, and bonding the substrates to each other to hermetically seal the inside of a sealing region surrounded by a sealing material, which is formed on any of the substrates. The sealing material is formed of a sintered body obtained by sintering a metal powder of at least one selected from gold, silver, palladium and platinum, the metal powder having a purity of 99.9% by weight or more and an average particle size of 0.005 µm to 1.0 µm, at least one core material having a width smaller than the width of the sealing material in a cross-sectional shape, and protruding from the periphery is formed on the substrate, and the core material compresses the sealing material to exhibit a sealing effect when the pair of substrates are bonded to each other. Accordingly, a sufficient sealing effect can be exhibited while a pressuring force to the substrate is reduced.