Semiconductor Conductor Member Roughness Control

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Solution Overview

Problem

The existing semiconductor devices face issues with excessive solder overflow during the soldering process, which can lead to short circuits and insufficient insulation if it spreads onto the semiconductor chip, and decreased durability if it covers the conductor member's surface, affecting the adhering degree between the conductor member and the encapsulant.

Innovation Solution

The semiconductor device incorporates a conductor member with a side surface featuring both roughened and unroughened areas, where the roughened areas have high surface roughness and low solder wettability, causing excessive solder to primarily spread on the unroughened areas, thereby suppressing its spread onto the roughened areas and improving adherence to the encapsulant, thus enhancing device durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the conductor member surface is broadly covered by solder, then the risk of short circuiting is reduced, but the adhering degree between the conductor member and encapsulant decreases

Engineering Contradiction:

Improverisk of short circuitingVSAvoidadhering degree between conductor member and encapsulant

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The side surface of the conductor member is divided into two regions with different surface roughness: a first region with smaller surface roughness and a second region with larger surface roughness. This local quality differentiation allows the first region to have high solder wettability (preventing short circuits) while the second region maintains strong adhesion to the encapsulant.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The side surface is segmented into distinct functional zones: the first region (adjacent to the joint surface periphery) with smaller roughness for solder reception, and the second region with larger roughness for encapsulant adhesion. This segmentation resolves the contradiction by assigning different properties to different segments of the same surface.

Inventive Principle:

Principle #1Segmentation

2Strength

If excessive solder spreads onto the semiconductor chip, then the joint strength is improved, but defects such as short circuiting and insufficient insulation occur

Engineering Contradiction:

Improvejoint strengthVSAvoidshort circuiting and insufficient insulation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The first region with smaller surface roughness acts as an intermediary zone that receives and contains excessive solder, preventing it from reaching the semiconductor chip. This intermediary region with controlled wettability serves as a buffer between the joint area and the chip, maintaining joint strength while blocking harmful solder spread.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If the surface roughness of the conductor member is increased, then the adhesion to encapsulant is improved, but solder wettability decreases

Engineering Contradiction:

Improveadhesion to encapsulantVSAvoidsolder wettability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

Different regions of the side surface are assigned different surface roughness values: the first region has smaller roughness for high solder wettability, while the second region has larger roughness for high encapsulant adhesion. This local quality approach allows both requirements to be satisfied in their respective zones.

Inventive Principle:

Principle #3Local quality

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 configuration effectively prevents excessive solder from covering the conductor member's surface, reducing the risk of short circuits and improving the adhering degree between the conductor member and the encapsulant, thereby enhancing the durability of the semiconductor device.

Implementation Method 1

Since the roughened area has large surface roughness, its solder wettability is low. As such, when the semiconductor chip and the conductor member are soldered together, excessive solder primarily spreads on the unroughened area while on the other hand it is suppressed from spreading onto the roughened area.

Methodology Applied

Scientific EffectSurface roughness effect on wettability: Wetting

Implementation Method 2

since the roughened area not covered by the solder has the large surface roughness, it can firmly adhere to the encapsulant. With an adhering degree between the conductor member and the encapsulant being improved, the durability of the semiconductor device is further improved.

Methodology Applied

Scientific EffectSurface roughness effect on adhesion: Adhesive

Data Source

PatentUS11244880B2Semiconductor device

Publication Date: 2022.02.08 DENSO CORP

AI summary

A semiconductor device may be provided with: a semiconductor chip; an encapsulant encapsulating the semiconductor chip therein; and a conductor member joined to the semiconductor chip via a solder layer within the encapsulant. The conductor member may comprise a joint surface in contact with the solder layer and a side surface extending from a peripheral edge of the joint surface. The side surface may comprise an unroughened area and a roughened area that is greater in surface roughness than the unroughened area. The unroughened area may be located adjacent to the peripheral edge of the joint surface.