Column Deposit Bonding by Substrate Inversion for Vertical Alignment

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Solution Overview

Problem

Existing methods face challenges in accurately positioning and aligning column type deposits with high aspect ratios on a substrate due to their small size and light weight, leading to tilting and defects during the soldering process.

Innovation Solution

A method involving the application of flux to metal connection layers, mounting column type deposits, rotating the substrate upside down, and heating to melt and harden the metal connection layers, leveraging gravity for vertical alignment and accurate bonding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If column type deposits with high aspect ratio are used to electrically connect upper and lower semiconductor chips, then electrical connection capability is improved, but positioning accuracy and alignment precision deteriorate due to small size and light weight

Engineering Contradiction:

Improveelectrical connection capabilityVSAvoidpositioning accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The substrate is inverted (rotated 180 degrees) after mounting the column type deposits but before heating. This inversion changes the direction of gravitational force acting on the deposits, causing them to tilt in the opposite direction and achieve vertical alignment during the subsequent heating process, thereby solving the positioning and alignment accuracy problem

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If pressing plate method is used to bond column type deposits, then bonding process is simplified, but uniformity of pressing deteriorates due to variable substrate surface height

Engineering Contradiction:

Improvebonding process simplicityVSAvoidpressing uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Instead of using a pressing plate that requires uniform substrate surface, the method inverts the substrate after deposit mounting. This eliminates the need for pressing plate contact with variable surface heights, allowing all column type deposits to be uniformly heated and bonded without mechanical pressing, thereby maintaining process simplicity while achieving pressing uniformity

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If column type deposits are mounted upright on substrate, then mounting process is straightforward, but vertical alignment deteriorates due to viscosity of solder paste or flux during heating

Engineering Contradiction:

Improvemounting process simplicityVSAvoidvertical alignment

Core Design Contradiction:

Ease of operationVSShape

Solution Approach 1:

The substrate is inverted after mounting the column type deposits in an upright position. This inversion reverses the gravitational effect during heating, causing the deposits to tilt backward and achieve vertical alignment, thereby maintaining ease of mounting while solving the vertical alignment problem caused by flux viscosity

Inventive Principle:

Principle #13The other way round (Inversion)

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

Ensures precise and accurate bonding of column type deposits to the substrate, reducing defects and improving process quality by aligning them vertically without additional complex equipment.

Implementation Method 1

applying a flux to the metal connection layers of the plurality of electrode pads on the substrate

Methodology Applied

Scientific EffectWetting: Wetting

Implementation Method 2

heating an assembly of the substrate and the column type deposits to melt the metal connection layers of the substrate

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

cooling the assembly of the substrate and the column type deposits so that the melted metal connection layers of the substrate are hardened

Methodology Applied

Scientific EffectFreezing: Freezing

Implementation Method 4

mounting column type deposits on upper surfaces of the metal connection layers on the flux-applied substrate, respectively; rotating the substrate upside down

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS12568589B2Method of bonding column type deposits

Publication Date: 2026.03.03 PROTEC CO LTD

AI summary

Provided is a method of bonding column type deposits, and more specifically, a method of bonding, to a substrate, column type deposits which are formed in a column shape and connect a substrate and electrodes of a semiconductor chip so as to connect the semiconductor chip to the substrate. The method of bonding the column type deposits to the substrate enables bonding the column type deposits having a high aspect ratio to accurate positions while being kept aligned vertically on the substrate.