Recessed Copper Clip Edge for Semiconductor Solder Reliability

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Solution Overview

Problem

In semiconductor devices, insufficient clearance between a large-area copper connector and a silicon chip can lead to bonding failures and solder fillet formation issues, resulting in defective products due to mechanical and electrical connection problems.

Innovation Solution

A semiconductor device configuration that includes a lead frame, a silicon chip, and a copper clip with a recessed outer peripheral edge, positioned inside the clip's outermost edge, which secures effective clearance with a non-conductive surface protection film, preventing solder fillet formation failures and reducing copper clip movement during the reflow process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a large-area copper connector is used to bond to a silicon chip, then electrical connection area is improved, but clearance with the bonding face cannot be secured leading to bonding failure

Engineering Contradiction:

Improvecopper connector areaVSAvoidbonding reliability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The copper connector is divided into a bonding portion and a non-bonding portion. The non-bonding portion is positioned at a lower height than the bonding portion, creating a stepped structure that segments the connector into functional zones with different clearance requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces a height dimension differentiation between the bonding portion and non-bonding portion of the copper connector. By creating a vertical height difference, the design maintains adequate clearance in the horizontal plane while preserving large bonding area, thus resolving the contradiction between area and clearance.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If copper connector area is increased, then electrical connection is improved, but solder fillet formation fails due to insufficient clearance

Engineering Contradiction:

Improvecopper connector areaVSAvoidsolder fillet formation

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The copper connector is segmented into bonding portion and non-bonding portion with different heights. This segmentation allows the bonding portion to provide large area for electrical connection while the non-bonding portion maintains clearance for proper solder fillet formation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the copper connector are given different heights and functions. The bonding portion has greater height for electrical connection, while the non-bonding portion has reduced height to maintain clearance, applying local quality variations to resolve the contradiction.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If copper connector area is enlarged, then electrical connection is improved, but copper clip movement increases during reflow process

Engineering Contradiction:

Improvecopper connector areaVSAvoidcopper clip position stability

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The copper connector is segmented into bonding portion and non-bonding portion. The non-bonding portion with reduced height has less mass and can be better controlled, while the bonding portion maintains large area for electrical connection, thus improving overall position stability during reflow.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The height parameter of the copper connector is changed differently for different portions. The non-bonding portion has reduced height which decreases its mass and moment of inertia, making it more stable and less prone to movement during the reflow process while maintaining large bonding area.

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 configuration ensures reliable solder fillet formation, improves crack resistance, and enhances product yield by maintaining effective clearance and stabilizing the copper clip position, thereby preventing solder connection failures.

Implementation Method 1

Connections between the electrodes and the connectors, and connections between the lead frame and the connectors, are mechanically and electrically made by a conductive adhesive agent such as solder

Methodology Applied

Scientific EffectSoldering: Soldering

Implementation Method 2

For a semiconductor package manufactured by, for example, bonding a silicon (Si) chip to a lead frame and copper (Cu) connectors with lead solder and performing mold sealing, a reflow furnace is used in the bonding process

Methodology Applied

Scientific EffectHeating: Heating

Data Source

PatentUS20230092121A1Semiconductor device

Publication Date: 2023.03.23 KK TOSHIBA

AI summary

According to one embodiment, a semiconductor device includes a lead frame, a semiconductor chip, and a clip member. The semiconductor chip is mounted on the lead frame. The clip member is connected to an electrode of the semiconductor chip via a conductive adhesive agent. At least part of an outer peripheral edge of a connection face of the clip member is located at a position more inside than an outermost peripheral edge of the clip member in plan view.