Wettable Flank Component Fabrication for Visible Solder Inspection

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Solution Overview

Problem

There is a need for improved manufacturing processes of electronic components with wettable flanks to ensure reliable and visible connections, particularly in applications where connections are not visible and require assurance of electrical reliability, such as in the automotive and medical fields.

Innovation Solution

A manufacturing process involving substrate formation with chip connection pads, optional cavity creation, insulating material deposition, conductive material bridging, and selective thinning to create components with accessible wettable sidewalls, using insulating and conductive materials like epoxy resin and SnAgCu for reliable soldering verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional manufacturing processes are used for leadless components, then the connections are not visible, but it becomes difficult to verify connection quality and reliability

Engineering Contradiction:
Improveconnection reliabilityVSAvoidconnection verification difficulty
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent extends the conductive material from the top surface into the cavities/trenches between chips, creating vertical sidewalls that are accessible from the sides. This dimensional transition from purely planar to three-dimensional exposed surfaces enables visual inspection and verification of connection quality without requiring X-ray or other complex detection methods.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent extracts the conductive material from being completely enclosed within the substrate structure and exposes it on the sidewalls by forming cavities and selectively removing insulating material. This extraction makes the previously hidden connection points visible and accessible for verification while maintaining their electrical function.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If insulating material is deposited to cover connection pads, then electrical insulation is improved, but the connection pads become inaccessible for subsequent processing

Engineering Contradiction:
Improveelectrical insulationVSAvoidpad accessibility
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies insulating material selectively - covering connection pads in some areas while leaving other areas accessible. The first insulating layer is deposited over the entire surface including pads, then selectively removed in specific regions to expose pads for conductive material deposition, while maintaining insulation in other regions. This local differentiation resolves the contradiction between insulation and accessibility.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent performs preliminary actions in sequence: first deposits insulating material to ensure electrical isolation, then selectively removes it where needed, and finally deposits conductive material. This preliminary insulation followed by selective exposure ensures that electrical isolation is established before any accessibility modifications are made.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If chips are separated by cutting through the substrate, then individual components are obtained, but the conductive material connections are severed

Engineering Contradiction:
Improvecomponent separationVSAvoidconductive connection
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent transitions the conductive connection from a purely horizontal top-surface configuration to a three-dimensional structure that extends down into cavities and along sidewalls. This dimensional change creates redundant connection paths, so that when chips are separated by cutting through the substrate, the conductive material remaining on the exposed sidewalls maintains the electrical connection.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent prepares the structure in advance by forming cavities and exposing conductive material on sidewalls before separation occurs. This preliminary configuration ensures that when cutting separates the chips, the conductive material already positioned on the sidewalls provides continuous electrical connection, cushioning against the potential harm of connection severing.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

4Reliability

If solder material is applied to connect components, then electrical connections are established, but visual inspection of connection quality becomes difficult

Engineering Contradiction:
Improveelectrical connectionVSAvoidconnection inspection
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent creates vertical sidewalls with exposed conductive material, providing a new dimensional plane for solder application and inspection. Solder can be applied to these exposed sidewalls and will be visible from the sides, enabling visual verification of connection quality without requiring destructive testing or complex imaging equipment.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

Enables reliable electrical connections with visible soldering verification, reducing the need for X-ray inspections and ensuring mechanical strength and connection reliability in surface-mount components.

Implementation Method 1

deposit a layer of conductive material so as to connect the connection pads of two adjacent chips

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

form a first layer of insulating material on the substrate, with the first layer of insulating material covering the upper face of the substrate

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

position a soldering material between the conductive material positioned on the top face of the electronic component and the connection elements of the external device, solder the soldering material

Methodology Applied
Scientific EffectSoldering: Soldering

Data Source

PatentEP4651204A1Method for producing electronic components with wettable flanks
Publication Date: 2025.11.19 STMICROELECTRONICS INT NV
  • EP4651204A1 patent drawingFigure 1A~1H
  • EP4651204A1 patent drawingFigure 1I~2G
  • EP4651204A1 patent drawingFigure 2H~4

AI summary

This description relates to a method comprising the following steps: a) providing a substrate (300) in which chips (100) are formed, with connection pads (107) arranged on the substrate (300), and conductive pads (117) that can cover the connection pads (107); b) optionally, forming cavities (307) between the chips (100); c) depositing a layer of insulating material (121) on the substrate (300) and in the cavities (307); d) making the connection pads (107) or the conductive pads (117) accessible; e) depositing a layer of conductive material (122) to connect the connection pads of two adjacent chips; f) depositing an additional layer of insulating material (123); g) thinning the additional layer (123) until the conductive material (122) is accessible; h) separating the electronic components (1000) through the cavities. (307),whereby the conductive material (122) forms the wettable flanks of the electronic components (1000).