Warpage-Proof Circuit Board Metal Frame

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Solution Overview

Problem

Multi-layer circuit boards experience warpage due to thermal stress from differing Coefficients of Thermal Expansion (CTE) of materials, leading to potential delamination and damage to semiconductor chips, and inefficient heat dissipation.

Innovation Solution

A warpage-proof circuit board structure is designed with an inner layer circuit board, dielectric layers, solder masks, and metal frames that protrude from grooves in the dielectric and solder masks, providing a metal support element to enhance strength and facilitate heat dissipation through rectangular metal frames.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multi-layer circuit board structure is used to expand circuit area, then circuit area is increased, but warpage occurs due to thermal stress from different CTE of materials

Engineering Contradiction:

Improvecircuit areaVSAvoidstructural stability

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent introduces a support layer with specific mechanical properties (elastic modulus, Poisson's ratio, thermal expansion coefficient) that differ from traditional circuit board layers. By changing the physical parameters of the support layer, the patent compensates for thermal stress and prevents warpage while maintaining the multi-layer circuit board structure.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure consisting of circuit board layers combined with a support layer made of specific materials (metal, ceramic, or composite materials). This composite approach allows the support layer to provide mechanical strength and thermal stability, counteracting the warpage caused by differential thermal expansion of the circuit board materials.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If traditional circuit board structure is used, then manufacturing process is simple, but heat dissipation efficiency is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidheat dissipation efficiency

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The support layer is designed with specific thermal conductivity parameters that are higher than traditional circuit board materials. By changing the thermal parameters of the board structure through the support layer, heat dissipation efficiency is significantly improved while maintaining compatibility with existing manufacturing processes.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If circuit board undergoes temperature variation during manufacturing, then circuit board is formed, but thermal stress causes warpage and delamination

Engineering Contradiction:

Improvemanufacturing process completionVSAvoidstructural integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The support layer is introduced beforehand to provide mechanical support and stress distribution during the manufacturing process. This pre-existing structural element cushions against thermal stress during temperature variations, preventing warpage and delamination before they occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The support layer's thermal and mechanical parameters are specifically selected to match and compensate for the thermal stress generated during manufacturing processes. This parameter optimization ensures structural integrity throughout the manufacturing cycle.

Inventive Principle:

Principle #35Parameter changes

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 structure prevents warpage caused by temperature variations and improves heat dissipation, increasing the robustness and reliability of the circuit board.

Implementation Method 1

Since the Coefficient of Thermal Expansion (CTE) of the metal circuit layers and the dielectric layer and the solder masks are quite different, warpage is caused by temperature variation of a manufacturing process of the circuit board structure

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Implementation Method 2

Heat that is not efficiently dissipated may be adverse to the life of the semiconductor chips

Methodology Applied

Scientific EffectHeat dissipation: Conduction (thermal)

Data Source

PatentUS7875805B2Warpage-proof circuit board structure

Publication Date: 2011.01.25 UNIMICRON TECH CORP

AI summary

The invention provides a warpage-proof circuit board structure, including: an inner layer circuit board; at least one dielectric layer formed on at least one surface of the inner layer circuit board; at least one first groove formed in the at least one dielectric layer corresponding in position thereto; a solder mask formed on the surface of the dielectric layer, a second groove formed in the solder mask and corresponding in position to the first groove formed in the dielectric layer; and a metal frame formed in the first and second grooves and protruding from the surface of the solder mask, thereby strengthening the circuit board to prevent it from warping in thermal processing and further using the metal frame as a heat-dissipating means for the package structure.