Flux-Free Chip Substrate Bonding via Copper Core Exposure

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Solution Overview

Problem

In the manufacturing of chip integrated substrates, the use of wire bonding methods can lead to issues such as wire breakage or deformation due to cleaning solutions, resulting in short circuits, especially when the chip component is mounted near the bump area, where the cleaning solution may inadvertently contact the wires.

Innovation Solution

The method involves connecting a chip component to a first substrate through wire bonding and using a flux non-containing conductive bonding member to bond the connecting pad to an exposed metal core or metallic electrode, eliminating the need for flux cleaning and preventing wire damage by ensuring precise spacing and protection with a sealing resin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cleaning treatment is carried out to remove flux residue after soldering, then the flux is reliably removed, but the cleaning solution may be injected onto the wire, causing wire breakage or deformation and short circuits

Engineering Contradiction:

Improvesoldering bond reliabilityVSAvoidwire breakage and short circuit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The harmful flux is extracted and removed from the system by using a flux non-containing conductive bonding member, eliminating the need for cleaning treatment and preventing wire damage from cleaning solution injection

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The potential harm of flux residue is converted into a benefit by using a flux non-containing bonding material, which eliminates the cleaning step and prevents wire damage, thereby improving overall manufacturing reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Area of stationary object

If the chip component is mounted near the bump area to reduce substrate size, then space saving is achieved, but the cleaning solution may inadvertently contact the wires, causing wire breakage or deformation

Engineering Contradiction:

Improvesubstrate sizeVSAvoidwire damage from cleaning solution

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The cleaning solution is extracted from the manufacturing process by using a flux non-containing conductive bonding member, eliminating the source of wire damage and enabling closer chip mounting to the bump area

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If solder flux is applied to enhance wettability during soldering, then the reliability of soldering bond is improved, but flux residue causes corrosion and requires cleaning treatment

Engineering Contradiction:

Improvesoldering bond reliabilityVSAvoidflux residue corrosion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The harmful flux is completely removed from the bonding process by using a flux non-containing conductive bonding member, eliminating corrosion risks while maintaining bonding reliability through alternative bonding mechanisms

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The conductive bonding member is designed to be applied in a controlled manner with precise positioning, allowing for reliable bonding without the need for flux, thereby eliminating residue corrosion issues

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS7754535B2Method of manufacturing chip integrated substrate

Publication Date: 2010.07.13 SHINKO ELECTRIC IND CO LTD

AI summary

There are provided the steps of connecting a chip component 13 to a first substrate 10 through wire bonding, providing, on a second substrate 20, an electrode 21 having a solder coat 23 with a copper core 22, polishing a portion of the electrode 21 which is to be bonded to the connecting pad 12, thereby exposing the copper core 22 from the solder coat 23, bonding the exposed portion of the copper core 22 to the bump connecting pad 12 by using a flux non-containing conductive paste 30, thereby bonding the substrates 10 and 20 to each other, and filling a sealing resin 40 in a clearance portion between the substrates 10 and 20.