Soluble Tacky Sheet Layout for Clean Semiconductor Package Peeling

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Solution Overview

Problem

In the production of semiconductor packages using the coreless buildup method, the thin buildup layers often curve and peel off, leading to disconnection and reduced connection reliability, and there is a risk of chemical liquid contamination and unintended peeling of the reinforcing sheet during the peeling process.

Innovation Solution

A tacky sheet with a soluble tacky layer in an intermittent pattern and a linear banking tacky layer surrounding the periphery is used to reinforce the redistribution layer, allowing for controlled peeling and minimizing chemical liquid penetration and unintended peeling by delaying the chemical liquid's reach to the soluble tacky layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a soluble tacky layer is used in an intermittent pattern to facilitate peeling, then peeling efficiency is improved, but chemical liquid can penetrate through the gaps causing contamination and unintended peeling

Engineering Contradiction:

Improvepeeling efficiencyVSAvoidchemical liquid contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The tacky layer is divided into two functional segments: a soluble tacky layer in intermittent pattern for peeling facilitation, and a waterproof backing layer in linear pattern providing barrier function. This segmentation allows each layer to perform its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tacky sheet uses a composite structure combining a soluble tacky layer (made of alkali-soluble resin) with a waterproof backing layer (made of water-insoluble resin). This composite material approach allows the sheet to provide both peeling facilitation and chemical liquid barrier functions simultaneously.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If the buildup layer thickness is reduced to meet thinning requirements, then weight and size are reduced, but the buildup layer curves and peels off causing disconnection

Engineering Contradiction:

Improvewiring board weightVSAvoidconnection reliability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The waterproof backing layer is applied locally at the periphery of the soluble tacky layer, providing reinforcement exactly where needed to prevent curvature and peeling, while maintaining the overall thin profile of the buildup layer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The waterproof backing layer serves as a preventive measure applied before peeling, cushioning against the harmful effects of chemical liquid penetration and providing structural support to prevent curvature and disconnection during the peeling process.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Manufacturing precision

If a reinforcing sheet is laminated to improve handleability, then coplanarity and connection reliability are improved, but the reinforcing sheet may peel off unintendedly during the process

Engineering Contradiction:

ImprovecoplanarityVSAvoidadhesion stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The tacky sheet's adhesive properties are changed by controlling the solubility characteristics of the tacky layer. The layer is designed to be insoluble during the buildup process (maintaining stable adhesion) but soluble during peeling (allowing controlled detachment), thus adapting the adhesion parameter at different process stages.

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

This method effectively suppresses chemical liquid contamination and unintended peeling of the reinforcing sheet, improving the connection reliability and coplanarity of the redistribution layer, while allowing for efficient peeling and chip mounting processes.

Implementation Method 1

a tacky sheet including a soluble tacky layer provided in an intermittent pattern

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

a linear banking tacky layer surrounding a periphery of a region wherein the soluble tacky layer exists on the surface

Methodology Applied

Scientific EffectChemical resistance:

Data Source

PatentUS11935865B2Semiconductor package manufacturing method, and adhesive sheet used therein

Publication Date: 2024.03.19 MITSUI MINING & SMELTING CO LTD

AI summary

A method for producing a semiconductor package, capable of effectively suppressing contamination of a chemical liquid and unintended peeling-off of a reinforcing sheet, is provided. This method includes providing a tacky sheet including a substrate sheet, and a soluble tacky layer and a banking tacky layer on at least one surface of the substrate sheet; making a first laminate including a redistribution layer; using the tacky sheet to obtain a second laminate having a second support substrate bonded to a surface on the redistribution layer side of the first laminate with the tacky layer therebetween; peeling off the first support substrate, pretreating the resulting third laminate; mounting a semiconductor chip on a pretreated surface of the redistribution layer; immersing the third laminate in a solution to dissolve or soften the tacky layer; and peeling off the second support substrate in a state where the tacky layer is dissolved or softened.