Pin Holder Cavity Alignment for Lead-Free Power Module Assembly

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Solution Overview

Problem

Conventional power electronic devices, such as power inverters, face challenges in achieving accurate positioning of electrically-conductive pins due to poor alignment caused by solder reflow and lead-free solder alloys, which can lead to impaired electrical connections and reduced manufacturing yield.

Innovation Solution

The method involves providing substrates with patterned electrically-conductive tracks and containment structures having perimeter walls that define cavities for pin holders. Pin holders are soldered within these cavities, allowing for self-alignment during the soldering process, thereby improving the accuracy of pin positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lead-free solder alloys are used for soldering pins to substrates, then compliance with lead-free banning legislation is achieved, but solder material melts easily causing poor positioning accuracy

Engineering Contradiction:

Improvecompliance with lead-free banning legislationVSAvoidpositioning accuracy of pins

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by providing containment structures on the substrate before soldering the pin holders. These containment structures are formed in advance to guide and constrain the pin holders during the soldering process, preventing misalignment caused by solder reflow. This preliminary structural preparation ensures accurate positioning is maintained throughout the soldering operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The containment structures act as an intermediary element between the substrate and the pin holders. They provide a physical guide and constraint mechanism that mediates the positioning relationship, ensuring that pin holders are correctly positioned relative to the substrate during soldering, thereby compensating for the melting and reflow of lead-free solder material.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If substrates are soldered to a common heat sink, then thermal management is achieved, but reflow of solder material causes misalignment between multiple substrates

Engineering Contradiction:

Improvethermal management capabilityVSAvoidalignment accuracy between substrates

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The containment structures are formed on each substrate before the substrates are attached to the heat sink. This preliminary action ensures that when multiple substrates are later soldered to the common heat sink, each substrate's pin holders are pre-positioned accurately, maintaining alignment even during the thermal reflow process of attaching substrates to the heat sink.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If electrically-conductive pins are soldered directly to substrates without containment structures, then manufacturing process is simple, but positioning accuracy deteriorates due to solder reflow

Engineering Contradiction:

Improvesimplicity of manufacturing processVSAvoidpositioning accuracy of pins

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The containment structures are integrated into the substrate manufacturing process itself, being formed as part of the substrate preparation before pin holder attachment. This approach adds minimal complexity to the manufacturing process while dramatically improving positioning accuracy, as the containment structures are already in place to guide pin holder placement and prevent solder reflow misalignment.

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

This approach enhances the accuracy of pin positioning, reduces misalignment issues, and increases the mechanical yield during the assembly of power electronic devices by ensuring precise alignment of electrically-conductive pins.

Implementation Method 1

The solder material may easily melt when power ceramic substrates are attached to the heat sink by a tin-based alloy

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS12322684B2Method of manufacturing electronic devices and corresponding electronic device

Publication Date: 2025.06.03 STMICROELECTRONICS SRL

AI summary

A substrate includes electrically-conductive tracks. A semiconductor chip is arranged on the substrate and electrically coupled to selected ones of the electrically-conductive tracks. Containment structures are provided at selected locations on the electrically-conductive tracks, where the containment structures have respective perimeter walls defining respective cavities. Each cavity is configured to accommodate a base portion of a pin holder. These pin holders are soldered to the electrically-conductive tracks within the cavities defined by the containment structures. Each containment structure may be formed by a ring of resist material configured to receive solder and maintain the pin holders in a desired alignment position.