Wiring Substrate Resin Layer Warping Correction
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Solution Overview
Problem
Conventional wiring substrates face reliability issues due to electronic components warping during manufacturing, causing uneven thickness in the insulating layer and reduced via hole reliability, which affects the connection between the wiring pattern and the electronic component's pad.
Innovation Solution
A wiring substrate design that includes a resin layer with a higher coefficient of thermal expansion than the insulating and adhesive layers to correct warping, ensuring uniform thickness and improved via hole reliability by thermally curing the resin, adhesive, and insulating layers simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electronic components are installed in a cavity of the first insulating layer via an adhesive layer, then the electronic component can be fixed in place, but the electronic component warps during manufacturing causing uneven thickness in the insulating layer
Solution Approach 1:
The patent introduces a resin layer with a higher coefficient of thermal expansion than the adhesive layer and insulating layers. During thermal curing, this resin layer expands more than the surrounding materials, generating upward force that counteracts the downward warp of the electronic component. This parameter change in thermal expansion behavior allows the resin layer to actively compensate for warping, maintaining uniform insulating layer thickness while preserving connection reliability.
Solution Approach 2:
The resin layer is positioned between the electronic component and the second insulating layer to preemptively counteract the warping force before it causes damage. By placing the high thermal expansion material in this strategic location, the system prepares an opposing force that activates during curing, preventing the insulating layer from becoming too thin in critical areas and maintaining via hole reliability.
2Reliability
If via holes are formed in the second insulating layer to connect wiring pattern to pad, then electrical connection is achieved, but uneven insulating layer thickness causes reduced via hole reliability
Solution Approach 1:
The resin layer's higher thermal expansion coefficient creates compensatory upward force during curing, preventing excessive thinning of the insulating layer in areas where via holes will be formed. This maintains more uniform via hole depth and bottom area, ensuring consistent electrical connection reliability across all via holes regardless of their position on the electronic component.
Solution Approach 2:
The resin layer acts as a cushioning element that preemptively compensates for warping-induced thickness variations. By positioning this high-expansion material beforehand, the system creates a buffer that absorbs and counteracts warping forces, protecting the via hole formation process from defects caused by uneven insulating layer thickness.
3Temperature
If the electronic component warps convexly during manufacturing, then the adhesive layer and insulating layer are heated, but the insulating layer becomes thinnest in the center and thicker toward the periphery
Solution Approach 1:
The resin layer exploits differences in thermal expansion parameters among materials. During heating, the resin layer expands more than the adhesive layer and insulating layers, generating upward pressure that counteracts the convex warp. This parameter-based approach allows the system to use thermal energy not just for curing but also for actively correcting thickness distribution, achieving both complete curing and improved uniformity.
Solution Approach 2:
The invention directly applies thermal expansion principles by selecting a resin layer with higher thermal expansion characteristics than surrounding materials. When heated during curing, this differential expansion creates mechanical force that opposes the warping tendency, transforming the thermal process from a potential source of distortion into a corrective mechanism that flattens the insulating layer thickness profile.
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 design enhances the reliability of the connection between the wiring pattern and the electronic component's pad by maintaining uniform via hole depth and area, thereby improving the overall connection reliability.
Implementation Method 1
A wiring substrate includes a first insulating layer, an electronic component, a resin layer, a second insulating layer, a wiring pattern, and a via interconnect. The resin layer is on the first surface of the electronic component and covers the pad. The second insulating layer is on the first insulating layer and covers the resin layer. The via interconnect pierces through the second insulating layer and the resin layer to electrically connect the wiring pattern to the pad.
Data Source
AI summary
A wiring substrate includes a first insulating layer, an electronic component, a resin layer, a second insulating layer, a wiring pattern, and a via interconnect. The first insulating layer includes a cavity. The electronic component includes a first surface at which a pad is formed and a second surface facing away from the first surface and fixed in the cavity via an adhesive layer. The resin layer is on the first surface of the electronic component and covers the pad. The second insulating layer is on the first insulating layer and covers the resin layer. The wiring pattern is on the second insulating layer. The via interconnect pierces through the second insulating layer and the resin layer to electrically connect the wiring pattern to the pad.