Plastic Leadframe Metallization for Low-Cost Semiconductor Packaging

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Solution Overview

Problem

Current semiconductor device manufacturing technologies face challenges in reducing assembly costs, flexibility in substrate manufacturing, and the need to replace metallic leadframes with cost-effective alternatives that simplify wire bonding and modular configurations for integrated circuits.

Innovation Solution

The use of a plastic leadframe with selective surface metallization and laser direct structuring (LDS) to create electrically-conductive patterns on a plastic substrate, allowing for the replacement of metallic leadframes with a less expensive option, enhancing flexibility in routing and simplifying wire bonding processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a metallic leadframe is used, then electrical conductivity and structural strength are ensured, but assembly cost increases and flexibility in routing is reduced

Engineering Contradiction:

Improveassembly costVSAvoidelectrical conductivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The plastic leadframe applies local quality by providing metallization only in specific areas where electrical conductivity is needed (leads and bonding pads), while the non-conductive plastic material is used in areas requiring insulation and structural support. This selective metallization approach reduces overall material cost while maintaining necessary electrical properties.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention uses a composite structure combining plastic material with metallic layers. The plastic substrate provides mechanical strength and insulation, while the deposited metal layers (such as copper, aluminum, or their alloys) provide electrical conductivity. This composite approach allows optimization of each material's properties for its specific function, reducing assembly cost while ensuring reliability.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If a plastic leadframe is used, then assembly cost is reduced and flexibility in routing is improved, but electrical conductivity must be achieved through additional processing

Engineering Contradiction:

Improveassembly costVSAvoidprocessing steps

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The plastic leadframe is pre-designed with integrated metallization patterns during the molding process. The metallic layers are deposited on the plastic substrate before subsequent assembly steps, so that electrical pathways are already established. This preliminary action eliminates the need for additional routing and wiring steps that would increase device complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces traditional mechanical wire bonding or trace routing with a direct metallization approach on the plastic substrate. By using laser direct structuring or other deposition methods to create conductive pathways directly on the plastic leadframe, the process substitutes complex mechanical assembly steps with a more integrated manufacturing approach, reducing overall processing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If selective surface metallization is applied, then electrical pathways are created on plastic substrate, but manufacturing complexity increases

Engineering Contradiction:

Improveelectrical pathwaysVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The metallization process utilizes parameter changes in the plastic material's surface properties. The plastic substrate is treated or prepared to enhance metal adhesion, and deposition parameters (such as laser power, deposition rate, or plating conditions) are optimized to create reliable electrical pathways. By controlling these parameters, the process achieves reliable metallization while managing manufacturing complexity through standardized process windows.

Inventive Principle:

Principle #35Parameter changes

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 enables the production of low-cost semiconductor devices with improved flexibility in routing and reduced complexity in wire bonding, facilitating the creation of cost-effective packages for integrated circuits.

Implementation Method 1

providing plastic material suitable for laser direct structuring (LDS) in the plastic core or substrate of the leadframe

Methodology Applied

Scientific EffectLaser direct structuring: Laser

Data Source

PatentUS11842954B2Method of manufacturing semiconductor devices and corresponding semiconductor device

Publication Date: 2023.12.12 STMICROELECTRONICS SRL

AI summary

A plastic material substrate has a die mounting location for a semiconductor die. Metallic traces are formed on selected areas of the plastic material substrate, wherein the metallic traces provide electrically-conductive paths for coupling to the semiconductor die. The semiconductor die is attached onto the die mounting location. The semiconductor die attached onto the die mounting location is electrically bonded to selected ones of the metallic traces formed on the plastic material substrate. A package material is molded onto the semiconductor die attached onto the die mounting location.