Thermoplastic Resin Substrate Bump Embedding for IC Mounting
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Solution Overview
Problem
Conventional methods for manufacturing electronic component mounting bodies face issues such as voids in under-fill resin, short circuits due to conductive particle bridges, and alignment challenges with thermoplastic resin substrates having high thermal expansion coefficients, leading to reduced electrical reliability and increased costs.
Innovation Solution
A method involving a bump burying step where bumps are inserted into a thermoplastic resin base material and partially exposed, followed by a conductor forming step using metal plating and precise alignment techniques to ensure reliable conductive connections, with the base material thickness controlled to minimize thermal distortion and enhance packing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If under-fill resin is filled between the electronic component and circuit board, then electrical reliability is improved, but the process becomes complex and voids are easily generated
Solution Approach 1:
The patent extracts and eliminates the under-fill resin filling process entirely by using a thermoplastic resin substrate that inherently provides both mechanical support and electrical connection functions. The bumps are directly inserted into the substrate without requiring separate resin filling, thereby removing the source of voids and process complexity while maintaining electrical reliability.
Solution Approach 2:
The thermoplastic resin substrate serves multiple functions simultaneously: it provides mechanical support, enables electrical connection through embedded bumps, and offers thermal management. This multi-functionality replaces the need for separate under-fill resin, achieving reliability improvement without adding process complexity.
2Reliability
If ACF with small conductive particles is used for narrow pitch terminals, then connection reliability is improved, but the ACF cost increases and short circuits occur due to particle bridges
Solution Approach 1:
The patent extracts and eliminates the ACF layer entirely by directly inserting metal bumps into the thermoplastic resin substrate. This removes the need for expensive small-particle ACF materials and eliminates the risk of conductive particle bridges causing short circuits, while maintaining reliable electrical connections.
Solution Approach 2:
The patent uses cost-effective metal bumps and thermoplastic resin substrate instead of expensive ACF materials. The simple bump insertion process provides reliable connections without requiring costly specialized materials, achieving both reliability and cost-effectiveness.
3Ease of manufacture
If IC chip is heated while pressed onto thermoplastic resin substrate, then mounting is achieved, but position accuracy of terminals is distorted due to thermal expansion
Solution Approach 1:
The patent performs preliminary actions by pre-forming bump holes in the thermoplastic resin substrate at precise positions before mounting the IC chip. The bumps are then inserted into these pre-positioned holes, which compensates for thermal expansion effects and maintains terminal position accuracy even during heating and pressing operations.
Solution Approach 2:
The patent changes the physical state of the thermoplastic resin substrate by heating it to a molten state during bump insertion, allowing the bumps to be securely embedded. The subsequent cooling and solidification process locks the bumps in precise positions, maintaining alignment accuracy despite the thermal cycle.
4Strength
If bumps are completely buried into the substrate, then mechanical strength is improved, but conductive connection to external circuits becomes difficult
Solution Approach 1:
The patent applies partial burial by inserting bumps into the thermoplastic resin substrate to a controlled depth where the bump ends remain exposed at the substrate surface. This partial exposure provides both mechanical anchoring strength through the embedded portion and accessible conductive connection points through the exposed ends, eliminating the need for additional external connection structures.
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 method improves electrical reliability and manufacturing efficiency by ensuring accurate alignment and reliable connections between bumps and conductors, reducing voids and short circuits, and lowering production costs.
Implementation Method 1
burying the bumps into the base material by heating and pressing the electronic component toward the base material
Implementation Method 2
forming a conductor conductively connected to the bumps by arranging conductive material on the surface of the base material on which the portion of the bumps are exposed
Data Source
AI summary
A method of manufacturing an electronic component mounting body is used for mounting an IC chip having a bumps as an external mounting terminal on a base material made of thermoplastic resin, comprising: a bump burying step of burying the bumps into the base material by heating and pressing the IC chip toward the base material to expose a portion of the bumps to a base material surface on the opposite side of the IC chip, and a step of forming a conductor conductively connected to the bump by arranging conductive material on the base material surface to which the portion of the bumps are exposed.