Semiconductor Bond Layout to Reduce Corner Thermal Stress

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Solution Overview

Problem

Conventional semiconductor devices experience thermal stress and defects due to the difference in coefficient of linear expansion between leads and conductive bonding materials, leading to issues like cracking and separation at the periphery of the semiconductor element.

Innovation Solution

The semiconductor device incorporates a conductive bonding material with extensions that extend outward from the corners of the semiconductor element, reducing thermal stress by maintaining a distance from the element's edges and using a dispenser to form the bonding material along specific directions, ensuring stable bonding and reduced separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the conductive bonding material is heated to bond the lead and the semiconductor element, then the bonding strength is improved, but thermal stress concentrates at the periphery causing cracks and separation

Engineering Contradiction:

Improvebonding strengthVSAvoidperipheral integrity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The conductive bonding material is configured with different properties in different regions: the peripheral portion has reduced thickness or is absent at the corners, while the central portion maintains sufficient thickness for electrical conductivity. This local variation reduces thermal stress concentration at the periphery during heating while preserving bonding strength in the central region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The conductive bonding material is segmented into a central portion and a peripheral portion with distinct characteristics. The central portion provides electrical connection, while the peripheral portion is designed with reduced material presence to minimize thermal stress. This segmentation allows each region to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the conductive bonding material is applied uniformly across the semiconductor element, then electrical conductivity is ensured, but thermal stress causes separation at the corners

Engineering Contradiction:

Improveelectrical conductivityVSAvoidbonding stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The conductive bonding material exhibits local quality variations where the central region maintains uniform thickness for optimal electrical conductivity, while the peripheral regions, particularly at corners, have reduced thickness or are absent. This spatially varying configuration ensures electrical functionality while preventing thermal stress-induced separation.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If the conductive bonding material extends to the corners of the semiconductor element, then complete coverage is achieved, but thermal stress concentration increases

Engineering Contradiction:

Improvebonding areaVSAvoidthermal stress

Core Design Contradiction:

Area of stationary objectVSStress or pressure

Solution Approach 1:

Instead of extending the conductive bonding material to the corners as conventionally done, the invention inverts this approach by deliberately reducing or eliminating material at the corner regions. This inverted configuration counterintuitively increases overall bonding reliability by preventing thermal stress concentration at these high-stress locations.

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

This configuration effectively reduces thermal stress and prevents defects such as cracking and separation, ensuring reliable bonding between the semiconductor element and the lead, enhancing the device's durability and performance.

Implementation Method 1

the conductive bonding material is heated to be bonded to the lead and the semiconductor element

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

thermal stress is produced in the conductive bonding material due to the difference in coefficient of linear expansion between the lead and the conductive bonding material

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20230378117A1Semiconductor apparatus and method for manufacturing semiconductor apparatus

Publication Date: 2023.11.23 ROHM CO LTD

AI summary

A semiconductor device includes a semiconductor element and a conductive bond bonding the semiconductor element to a support. The semiconductor element has first to fourth sides, and the bond has first to fourth edges. Distance between the first side and the first edge in first direction is greater at ends than at the center of the first side in second direction crossing first direction. Distance between the second side and the second edge in first direction is greater at ends than at the center of the second side in second direction. Distance between the third side and the third edge in second direction is greater at ends than at the center of the third side in first direction. Distance between the fourth side and the fourth edge in second direction is greater at ends than at the center of the fourth side in first direction.