Semiconductor Package Anchor Pad for PCB Thermal Fatigue

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Solution Overview

Problem

Existing semiconductor packages attached to PCBs via leads are susceptible to thermal fatigue and failure due to insufficient robustness of soldered joints, especially in top-cooled embodiments where stress levels are high.

Innovation Solution

Incorporating an anchor pad that extends across a significant portion of the die, providing an additional attachment point to the PCB, which is securely coupled to the die paddle via legs and encapsulated within the package, enhancing the connection's robustness and thermal management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If semiconductor packages are attached to PCB via leads only, then the structure is simple, but the soldered joints are susceptible to thermal fatigue and failure

Engineering Contradiction:

Improvethermal fatigue resistanceVSAvoidpackage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the anchor pad with the die paddle to form an integrated attachment structure. The anchor pad is formed as an extension of the die paddle, creating a unified component that provides both electrical connection and mechanical anchoring functions, thereby improving reliability without significantly increasing structural complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The anchor pad serves multiple functions: it provides mechanical anchoring to the PCB, acts as a heat dissipation path, and serves as an additional solder attachment point. This multi-functionality addresses the thermal fatigue issue while maintaining structural efficiency

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Strength

If leads are used for attachment, then the connection is established, but the stress on solder joints is high under thermal fatigue cycles

Engineering Contradiction:

Improveconnection robustnessVSAvoidstress on solder joints

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The patent segments the attachment function by introducing a separate anchor pad distinct from the leads. The anchor pad provides a dedicated attachment point that bears the mechanical and thermal stress, while the leads maintain their electrical connection function, thereby reducing stress concentration on the solder joints

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The anchor pad acts as an intermediary between the semiconductor die and the PCB. It provides a stable mechanical and thermal interface that mediates the stress transfer, protecting the vulnerable solder joints at the lead-PCB interfaces from excessive stress during thermal cycling

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If anchor pad extends across die, then attachment surface area increases, but manufacturing complexity increases

Engineering Contradiction:

Improveattachment surface areaVSAvoidmanufacturing process

Core Design Contradiction:

Area of stationary objectVSEase of manufacture

Solution Approach 1:

The anchor pad is formed as an integral extension of the die paddle, combining two components into one. This is achieved through a single metallization process that deposits conductive material across both the die paddle and the extended anchor pad region, simplifying manufacturing by eliminating separate assembly steps

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The anchor pad is pre-formed as part of the die paddle structure before the semiconductor die is mounted. The conductive material is deposited in advance to create the extended pad structure, preparing the attachment surface beforehand and streamlining the overall manufacturing process

Inventive Principle:

Principle #10Preliminary action

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

The anchor pad increases the surface area for attachment, reducing stress on leads and solder joints, improving thermal fatigue resistance and reliability, and providing a heatsink functionality for enhanced heat dissipation.

Implementation Method 1

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250105076A1Semiconductor package for a PCB

Publication Date: 2025.03.27 NEXPERIA BV

AI summary

There is disclosed a semiconductor package for a PCB. The semiconductor package includes a die paddle, a die, a connector, an anchor pad and an encapsulant. The die is coupled to the die paddle. The connector is coupled to the die, the connector including a plurality of leads for attachment to the PCB. The anchor pad is for attachment to the PCB. The encapsulant at least partly surrounds the die. The anchor pad extends across at least part of the die.