Semiconductor Package Surface Roughening to Limit Die Float

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Solution Overview

Problem

Existing attachment solutions for semiconductor packages using liquified materials face challenges as the mounted elements may drift during the attachment process, leading to misalignment issues in forming electrical interconnections.

Innovation Solution

A float-limiting attachment process is employed, which involves creating a border of roughened surface around the mounting area to impede the flow of liquified attachment material, using a surface roughening technique like masked etching, to restrict movement of the mounted components, ensuring precise positioning for reliable electrical interconnects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If liquified attachment materials are used to mount elements, then the attachment process becomes simpler and more flexible, but the mounted elements may drift during the attachment process

Engineering Contradiction:

Improveattachment process simplicityVSAvoidmounting element positioning accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The attachment surface is selectively roughened only at the periphery surrounding the mounting area, while the central mounting area maintains its original smoothness. This local differentiation allows the liquified attachment material to flow freely in the mounting area for easy element placement, while the roughened periphery creates capillary barriers that prevent material overflow and element drift, thus resolving the contradiction between manufacturing simplicity and positioning accuracy

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The surface roughening process is performed in advance before the attachment material is applied. This preliminary action creates the float-limiting structure that will later prevent element drift during the attachment process, allowing the use of liquified attachment materials without compromising positioning accuracy

Inventive Principle:

Principle #10Preliminary action

2Ease of operation

If a smooth attachment surface is used, then the attachment material flows easily for simple application, but the mounted elements drift during the attachment process

Engineering Contradiction:

Improveattachment material applicationVSAvoidmounted element position stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The attachment surface is divided into two regions with different properties: a smooth central mounting area that facilitates easy material application and element placement, and a roughened peripheral region that provides capillary barriers to prevent material overflow and element drift, thus maintaining both ease of operation and position stability

Inventive Principle:

Principle #3Local quality

3Productivity

If the attachment material is kept in liquid state during mounting, then the attachment process is simplified, but misalignment of mounted elements occurs

Engineering Contradiction:

Improveassembly process efficiencyVSAvoidelement alignment accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The selectively roughened periphery creates capillary barriers that contain the liquified attachment material within the mounting area, preventing element drift and misalignment while maintaining the benefits of using liquified attachment materials for simplified assembly processes

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The roughened surface structure acts as an intermediary mechanism that mediates between the liquified attachment material and the mounting element, providing a float-limiting effect that prevents misalignment while allowing the material to remain in liquid state for easy application

Inventive Principle:

Principle #24Intermediary (Mediator)

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 float-limiting attachment process effectively maintains the position of mounted elements, reducing misalignment and enabling reliable formation of electrical interconnections without part discard, thus enhancing the assembly process efficiency.

Implementation Method 1

performing a surface roughening process to an attachment surface that forms a border of roughened surface at least substantially surrounding a mounting area

Methodology Applied

Scientific EffectCapillary pressure: Capillary Pressure

Data Source

PatentUS20260068691A1Semiconductor Package with Selective Surface Roughening

Publication Date: 2026.03.05 INFINEON TECH AUSTRIA AG

AI summary

A method of forming a semiconductor package includes providing a metal lead frame comprising a die pad and a plurality of leads, mounting a high-voltage die on an upper surface of the die pad such that a load terminal of the high-voltage die is electrically connected to the die pad, mounting an electrical isolation pad on the die pad, and mounting a low-voltage die on the electrical isolation pad, wherein at least one of: mounting the high-voltage die, mounting the electrical isolation pad, and mounting the low-voltage die includes performing a float-limiting attachment process, wherein the float-limiting attachment process comprises performing a surface roughening process to an attachment surface that forms a border of roughened surface around a mounting area, arranging an attachment material within the mounting area with a mounting element disposed thereon, and liquifying the attachment material with the mounting element disposed thereon.