Printed Circuit Board Cavity Formation Using Photoimageable Dielectric
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Solution Overview
Problem
Conventional printed circuit boards face challenges in reducing thickness, forming reliable cavities for device mounting, and increasing production efficiency due to complex manufacturing processes and material compatibility issues, leading to increased costs and reliability concerns.
Innovation Solution
A printed circuit board design featuring a cavity formed in both photosensitive and non-photosensitive insulating layers, with a photoimageable dielectric outermost layer allowing for easy cavity formation and improved adhesion between layers, reducing the need for costly processes like laser drilling and sand blasting, and enhancing reliability by preventing peeling between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cavity is formed in conventional insulating layers using laser drilling or sand blasting, then device mounting space is created, but manufacturing cost increases and production time extends
Solution Approach 1:
The patent replaces mechanical cavity formation methods (laser drilling, sand blasting) with chemical etching using photoimageable dielectric materials. The cavity is formed by exposing the photoimageable dielectric layer to light, developing the exposed areas, and removing the developed material, thereby substituting complex mechanical/thermal processes with a simpler photochemical process that reduces manufacturing cost and time while maintaining reliability
Solution Approach 2:
The patent changes the material parameter of the insulating layer from conventional non-photoimageable materials to photoimageable dielectric materials. This parameter change enables the cavity formation process to utilize light exposure and chemical development instead of laser or mechanical methods, achieving both improved reliability through precise pattern control and enhanced productivity through simplified processing
2Reliability
If different materials are used for outermost and inner insulating layers, then adhesion improvement is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent introduces an additional insulating layer made of different material between the outermost photoimageable dielectric layer and the inner non-photoimageable insulating layer. This intermediate layer acts as a adhesion promoter that chemically or physically bonds to both layers, solving the adhesion problem between dissimilar materials while maintaining a manageable manufacturing process through standardized lamination and curing steps
3Ease of manufacture
If cavity formation processes are simplified, then production cost decreases, but peeling between layers may occur
Solution Approach 1:
The patent performs preliminary adhesion enhancement by disposing the additional insulating layer of different material between the outermost and inner insulating layers before cavity formation. This preliminary action ensures strong interlayer bonding is established in advance, preventing peeling during subsequent simplified cavity formation processes and maintaining reliability without requiring complex post-processing
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 enables a thinner package substrate, simplifies the manufacturing process, reduces production costs, and improves reliability by allowing for precise cavity formation and enhanced material adhesion, addressing the limitations of conventional methods.
Implementation Method 1
forming an outermost insulating layer of photoimageable dielectrics (PID)
Data Source
AI summary
A printed circuit board according to an embodiment includes a first insulating layer, a second insulating layer disposed on the first insulating layer, and a cavity formed in the first and second insulating layers; wherein the cavity includes a first portion formed in the second insulating layer, and a second portion formed in the first insulating layer; wherein the first portion has a first cross-sectional shape, and wherein the second part has a second cross-sectional shape different from the first cross-sectional shape.