Semi-flexible PCB with embedded components and tailored dielectric
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing printed circuit boards face mechanical stress and reliability issues due to thermal expansion mismatches between flame-retardant materials and semiconductor components, leading to warping and detachment of layers during temperature changes.
Innovation Solution
A printed circuit board design featuring a dielectric material with a low coefficient of thermal expansion (between 0 and 17 ppm/K) and a modulus of elasticity between 1 GPa and 20 GPa, which minimizes thermally induced mechanical stress by embedding electronic components, allowing for stress-free integration and high thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If flame-retardant material FR4 is used for printed circuit boards, then fire safety is improved, but thermal stress and layer warping occur due to coefficient of thermal expansion mismatch with semiconductor materials
Solution Approach 1:
The patent employs a composite material structure consisting of a thermoplastic resin matrix combined with specific fillers to create a dielectric layer with tailored thermal expansion properties. This composite approach allows the material to simultaneously provide fire safety and thermal compatibility with semiconductor components, resolving the contradiction between fire resistance and thermal stress prevention.
Solution Approach 2:
The invention modifies the physical and chemical parameters of the dielectric material by adjusting the coefficient of thermal expansion to match that of semiconductor materials (silicon). This parameter optimization eliminates thermal expansion mismatch, preventing layer warping and detachment while maintaining the fire safety requirements through appropriate material composition and formulation.
2Reliability
If electronic components are embedded in the circuit board, then traceability and identification are improved, but thermal stress leads to mechanical loads and reduced reliability
Solution Approach 1:
The patent optimizes the thermal expansion coefficient of the dielectric layer to match that of the embedded semiconductor components. This parameter alignment ensures that during temperature variations, both materials expand and contract at the same rate, eliminating relative movement and thermal stress that would otherwise compromise the mechanical strength and reliability of the embedded components.
3Adaptability or versatility
If multilayer printed circuit board is used, then functionality is improved, but individual layers warp and detach due to thermal stresses
Solution Approach 1:
The patent uses a composite dielectric material with specifically engineered thermal properties that acts as a thermal buffer between different layers. This composite layer maintains dimensional stability during temperature cycling, preventing the warping and detachment issues that plague conventional multilayer circuits while preserving the enhanced functionality provided by the multilayer structure.
Solution Approach 2:
The invention directly addresses thermal expansion mismatch by designing the dielectric layer with a coefficient of thermal expansion that closely matches that of semiconductor materials. This thermal expansion compatibility ensures that all layers in the multilayer structure expand and contract harmoniously, maintaining layer adhesion and preventing warping even as temperature fluctuates during operation.
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 solution ensures minimal warping and mechanical stress, enabling reliable embedding of components and maintaining mechanical stability even under extreme temperature fluctuations, suitable for high-performance applications like power modules.
Implementation Method 1
materials such as the flame-retardant material FR4, which is typically used for printed circuit boards, and semiconductor materials such as silicon (Si), which is typically used for electronic components, have very different coefficients of thermal expansion. This naturally leads to thermal stresses.
Implementation Method 2
The dielectric material has a coefficient of thermal expansion in the range between 0 and 17 ppm/K and a modulus of elasticity E in the range between 1 GPa and 20 GPa
Data Source
Figure 1
Figure 2
Figure 3
AI summary
This document describes a printed circuit board and a method for producing a printed circuit board or two printed circuit boards, wherein the printed circuit board comprises (a) a dielectric layer (312), which has a planar extent parallel to an xy plane spanned by an x axis and a y axis perpendicular thereto and has a layer thickness along a z direction perpendicular to the x axis and to the y axis; (b) a metallic layer (336), which is applied areally on the dielectric layer; and (c) a component (120), which is embedded in the dielectric layer (312) and/or in a dielectric core layer (350) of the printed circuit board (300). The dielectric layer (312) comprises a dielectric material which has (i) a modulus of elasticity E in the range of between 1 and 20 GPa and (ii) a coefficient of thermal expansion along the x axis and along the y axis in the range of between 0 and 17 ppm/K.