Embedded Component PCB Warping via CTE Mismatch
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Solution Overview
Problem
Printed wiring boards with embedded electronic components face warping issues due to thermal expansion mismatches between different layers, affecting the reliability of component mounting and connectivity.
Innovation Solution
A printed wiring board design featuring a first insulation layer with a higher coefficient of thermal expansion than the second insulation layer, combined with a conductive film on the electronic component's back surface, which reduces warping by offsetting thermal expansion discrepancies and enhancing mounting reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If electronic components are embedded in insulation layers without using a core substrate, then the wiring board becomes thinner, but warping occurs due to thermal expansion mismatches between different layers
Solution Approach 1:
The patent changes the physical parameter of the first insulation layer by setting its coefficient of thermal expansion higher than that of the second insulation layer. This parameter modification allows the first insulation layer to compensate for thermal expansion mismatches during temperature changes, thereby reducing warping while maintaining the thin-profile design without core substrate
Solution Approach 2:
The patent employs composite material structure by combining insulation layers with different coefficients of thermal expansion. The first insulation layer (with higher CTE) and second insulation layer (with lower CTE) work together as a composite system, where their differential thermal expansion properties are leveraged to counterbalance each other and minimize overall warping of the wiring board
2Reliability
If a conductive film is added on the electronic component's back surface, then mounting reliability improves, but device complexity increases
Solution Approach 1:
The conductive film on the electronic component's back surface serves multiple functions: it provides electrical connectivity to the component's backside contacts, acts as a thermal management path, and serves as a mechanical bonding interface for mounting. By consolidating these functions into a single layer, the patent improves mounting reliability without proportionally increasing device complexity
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 design effectively minimizes warping and improves the reliability of electronic component mounting by balancing thermal expansion and conductor area differences, leading to enhanced connectivity and stability.
Implementation Method 1
The first insulation layer has a coefficient of thermal expansion which is set higher than a coefficient of thermal expansion of the second insulation layer
Implementation Method 2
mounting a semiconductor component on the conductive film such that a back side of the semiconductor component is adhered to the conductive film via an adhesive agent
Data Source
AI summary
A printed wiring board includes a first insulation layer, an electronic component built into the first insulation layer, a second insulation layer having a via conductor and formed on a first surface of the first insulation layer, and a conductive film formed on the first insulation layer on the opposite side with respect to the first surface of the first insulation layer such that the conductive film is positioned to face a back surface of the electronic component. The first insulation layer has a coefficient of thermal expansion which is set higher than a coefficient of thermal expansion of the second insulation layer.