Supported Wiring Board Separation Using a Laser Absorption Layer

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Solution Overview

Problem

The existing methods for producing FC-BGA boards face challenges such as low productivity, high cost due to expensive silicon interposers, deterioration in transmission characteristics, and difficulties in forming fine wiring, along with issues related to warpage and strain of FC-BGA boards, especially when using silicon interposers or direct chemical mechanical polishing.

Innovation Solution

A board unit with support is developed, comprising a support, a release layer, a laser absorption layer, and at least one first wiring board, where the support is separated using low-energy laser irradiation, reducing residue formation and enabling efficient production without high-energy UV lasers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a release layer is irradiated with high-energy UV laser for support separation, then the support can be separated, but large processing load is required and residues are formed on the wiring board surface

Engineering Contradiction:

Improvesupport separationVSAvoidresidue formation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the laser energy parameter from high-energy UV laser to low-energy infrared laser, fundamentally altering the separation mechanism from photochemical reaction to thermal effect, thereby eliminating residue formation while achieving complete support separation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the photochemical separation mechanism (UV laser inducing photochemical reaction in release layer) with a thermal mechanism (infrared laser heating the laser absorption layer to decompose the release layer), substituting one physical field for another to achieve better results

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If silicon interposers are used for fine wiring, then transmission characteristics are maintained, but manufacturing cost increases and productivity decreases

Engineering Contradiction:

Improvetransmission characteristicsVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces expensive silicon interposers with a disposable support structure that can be easily removed via laser separation, achieving the same functional purpose at lower cost and higher productivity by using a temporary carrier that is discarded after serving its purpose

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces a support with release layer and laser absorption layer as an intermediary carrier that enables fine wiring formation on a temporary substrate, which is then easily removed to leave the fine wiring on the FC-BGA board, replacing the need for expensive silicon interposers

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If high-energy UV laser is used for support separation, then separation can be achieved, but processing load and equipment complexity increase

Engineering Contradiction:

Improvesupport separationVSAvoidlaser device requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the laser parameters from UV wavelength and high energy to infrared wavelength and low energy, simplifying the laser device requirements while achieving the same separation function through a different physical mechanism (thermal heating versus photochemical reaction)

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 approach enhances productivity by reducing residue formation and eliminating the need for high-energy UV lasers, while maintaining low transmission characteristic degradation and addressing warpage issues, thus improving the overall manufacturing efficiency and reliability of FC-BGA boards.

Implementation Method 1

a laser absorption layer that absorbs laser light

Methodology Applied

Scientific EffectLaser light absorption: Absorption (EM radiation)

Implementation Method 2

separated by irradiating the release layer with a laser

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 3

the support is separated by irradiating the release layer with a laser

Methodology Applied

Scientific EffectThermal heating: Heating

Data Source

PatentUS20230395395A1Board unit with support, board unit, and method of producing board unit with support

Publication Date: 2023.12.07 TOPPAN INC

AI summary

A board unit with support which does not require a high-energy UV laser and which is less likely to form residues of the release layer after separation of the support, a board unit, and a semiconductor device, and a method of producing them. The board unit with support includes a support, a release layer, a laser absorption layer that absorbs laser light, and at least one first wiring board in this order, wherein the at least one first wiring board has a first surface provided with first electrodes that can be bonded to at least one semiconductor element, the at least one first wiring board has a second surface provided with second electrodes that can be bonded to a second wiring board.