Multilayer Ceramic Substrate Cavity Formation via Thermal Expansion
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Solution Overview
Problem
Existing methods for producing multi-layer ceramic substrates with cavities face challenges in mass productivity and stability due to deformation of ceramic green sheets during pressure-bonding and difficulties in forming cavities accurately.
Innovation Solution
A method involving the use of thermal expansion layers, where a first ceramic green sheet with a thermal expansion layer is laminated with second ceramic green sheets, the thermal expansion layer is heated to expand and displace the green sheet, forming a cavity, and then the displaced portion is extracted, allowing for easy cavity formation and high productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ceramic green sheet with an opening is pressure-bonded to form a cavity, then the cavity structure is created, but the green sheet deforms during pressure-bonding
Solution Approach 1:
A groove is formed in the ceramic green sheet at the cavity position before pressure-bonding. This preliminary action defines the cavity boundary in advance, preventing deformation of the green sheet during the subsequent pressure-bonding process while ensuring accurate cavity formation.
Solution Approach 2:
The ceramic green sheet is segmented by forming a groove that divides the sheet into regions, with the groove defining the future cavity boundary. This segmentation allows the cavity portion to be cleanly separated and removed after sintering without affecting the overall structure.
2Productivity
If existing cavity formation methods are used, then cavities can be produced, but mass productivity is reduced due to process complexity
Solution Approach 1:
The groove is formed before sintering, allowing the cavity shape to be pre-defined in the green state. This eliminates the need for complex post-sintering processing steps, simplifying the overall process and enabling mass production.
Solution Approach 2:
The cavity portion is extracted from the green sheet laminate before sintering by removing the material within the groove boundaries. This extraction in the green state is simpler and more efficient than attempting to create cavities after sintering, thereby improving productivity.
3Manufacturing precision
If the cavity is formed by removing green sheet material before sintering, then the cavity shape can be controlled, but the structural strength is reduced
Solution Approach 1:
The groove is formed as a preliminary structure that defines the cavity boundary without completely removing material. This maintains structural integrity during handling while allowing precise cavity shape control. The actual material removal occurs only after sintering when the substrate is complete.
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 method enables the reliable and efficient formation of cavities in multi-layer ceramic substrates, improving mass productivity and yield by preventing deformation and ensuring accurate cavity formation before sintering, thus facilitating high integration and low profile modules.
Implementation Method 1
heating and thereby expanding the thermal expansion layer at least in a thickness direction in the pressure-bonded green sheet laminate
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3(a)~3(c)
AI summary
A method of prducing a multi-layer ceramic substrate includes the steps of: (A) preparing a first ceramic green sheet with a thermal expansion layer arranged thereon, and at least one second ceramic green sheet with no thermal expansion layer arranged thereon; (B) laminating the first and second ceramic green sheets with the thermal expansion layer sandwiched therebetween, thereby obtaining a green sheet laminate; (C) pressure-bonding together the ceramic green sheets of the green sheet laminate; (D) heating and thereby expanding the thermal expansion layer in the pressure-bonded green sheet laminate; (E) extracting a portion of the green sheet laminate that has been displaced by the expansion of the thermal expansion layer, thereby forming a cavity in the green sheet laminate; and (F) sintering the green sheet laminate with the cavity formed therein.