Solder Transfer Substrate With Holes For Peeling-Off Liquid

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Solution Overview

Problem

Conventional solder transfer substrates face issues with peeling off from semiconductor elements with low-dielectric-constant films and circuit boards, leading to electrode pad detachment due to strong adhesive bonding, especially when using fragile low-k films or weak adhesion forces between Cu electrode pads and silicone substrates.

Innovation Solution

A solder transfer substrate with a base layer having holes that allow a peeling-off liquid to pass through, an adhesive layer that expands with the liquid, and a porous base layer design to facilitate easy peeling, along with specific materials and manufacturing steps to ensure uniform heating and pressurization, reducing the bonding strength between the adhesive layer and electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the adhesive layer is made strongly bonded to ensure reliable solder attachment, then the solder transfer substrate can reliably transfer solder to electrode terminals, but the solder transfer substrate cannot be peeled off without damaging fragile low-dielectric-constant films or electrode pads

Engineering Contradiction:

Improvesolder attachment reliabilityVSAvoiddamage to fragile films during peeling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A peeling-off liquid is introduced as an intermediary substance that selectively interacts with the adhesive layer. The liquid penetrates through holes in the base layer and causes the adhesive layer to expand, reducing its bonding strength to enable peeling. This mediator allows the system to transition from a strongly bonded state (for reliable solder transfer) to a easily peelable state (for substrate removal) without damaging fragile components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bonding strength of the adhesive layer is dynamically changed by altering its physical state through exposure to peeling-off liquid. The adhesive layer transitions from a solid, strongly bonded state during solder transfer to an expanded, weakened state during peeling. This parameter change enables the same adhesive layer to fulfill contradictory requirements of strong bonding and easy peeling at different stages of the process.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional solder transfer substrates are used without holes in the base layer, then the structure is simpler and manufacturing is easier, but the peeling-off liquid cannot penetrate to expand the adhesive layer, making peeling difficult and causing damage to fragile structures

Engineering Contradiction:

Improvesubstrate manufacturing simplicityVSAvoidpeeling-off ease

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The base layer is designed with holes that allow the peeling-off liquid to penetrate through it and reach the adhesive layer. This porous structure enables the liquid to access and expand the adhesive layer, facilitating easy peeling. The holes are strategically positioned and sized to allow liquid penetration while maintaining the overall structural integrity and functionality of the substrate during manufacturing and solder transfer operations.

Inventive Principle:

Principle #31Porous materials

3Reliability

If the adhesive layer does not expand with peeling-off liquid, then the bonding strength remains high for reliable solder transfer, but the solder transfer substrate cannot be smoothly peeled off from the semiconductor element

Engineering Contradiction:

Improvesolder transfer reliabilityVSAvoidpeeling-off smoothness

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The adhesive layer's physical parameters (volume, density, bonding strength) are changed through exposure to peeling-off liquid. The liquid causes the adhesive layer to expand, which reduces its bonding strength and enables smooth peeling. This parameter change occurs only during the peeling stage, while the adhesive layer maintains its original strongly bonded state during solder transfer, thus resolving the contradiction between reliable solder transfer and easy peeling.

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

Enables smooth peeling off of the solder transfer substrate without damaging fragile low-dielectric-constant films or electrode pads, improving the reliability and productivity of solder layer formation on semiconductor elements and circuit boards with narrow pitches.

Implementation Method 1

the adhesive layer has a characteristic of expanding with the peeling-off liquid infused

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

in the base layer, a plurality of holes, which allow at least a peeling-off liquid to pass therethrough, are formed

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS9238278B2Solder transfer substrate, manufacturing method of solder transfer substrate, and solder transfer method

Publication Date: 2016.01.19 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A solder transfer substrate, including: a base layer; an adhesive layer arranged on the base layer; and plural solder powders arranged on the adhesive layer, wherein in the base layer, which is a porous member, a plurality of holes, which allow at least a peeling-off liquid to pass therethrough, are formed from a side thereof on which the adhesive layer is not arranged to a side thereof on which the adhesive layer is arranged. Particularly, the adhesive layer has a characteristic of expanding with the peeling-off liquid infused.