Wettable Flank Semiconductor Package With Half-Etched Tie Bars

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing semiconductor packages face challenges in efficiently encapsulating leads and tie bars while ensuring electrical isolation and promoting solder wetting.

Innovation Solution

The semiconductor package design includes a lead frame with half-etched tie bars, where the ends of the tie bars are exposed on the package's sidewalls, and the leads are electroplated to extend beyond the package surface, enhancing solder wetting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tie bars are fully etched to expose ends, then solder wetting is improved, but structural integrity and electrical isolation are compromised

Engineering Contradiction:

Improvesolder wettingVSAvoidstructural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Instead of fully etching the tie bars, the patent applies partial etching (half-etching) that exposes only the necessary lateral surfaces for solder wetting while leaving the top surfaces intact. This partial action provides sufficient solder access without compromising the structural integrity and electrical isolation that would be lost with full etching.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If more leads are exposed, then electrical connectivity is improved, but encapsulation complexity increases

Engineering Contradiction:

Improveelectrical connectivityVSAvoidencapsulation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The lead frame is designed with pre-positioned leads and tie bars in the mold compound before encapsulation. This preliminary arrangement allows the mold compound to be applied in a single operation, enclosing most components while leaving only the necessary lead ends exposed. This approach maintains electrical connectivity without requiring complex multi-step encapsulation processes.

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 design effectively encapsulates leads and tie bars, maintains electrical isolation, and improves solder wetting, leading to enhanced reliability and performance of semiconductor packages.

Implementation Method 1

An end of the first lead and an end of the second lead may each be electroplated

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 2

The first lead and the second lead may each extend from the first sidewall at least eight micrometers (μm)... improving solder wetting

Methodology Applied

Scientific EffectSolder wetting: Wetting

Data Source

PatentUS20250201675A1Semiconductor package with wettable flank and related methods

Publication Date: 2025.06.19 SEMICON COMPONENTS IND LLC

AI summary

Implementations of the semiconductor package may include a first sidewall opposite a second sidewall, and a third sidewall opposite a fourth sidewall. Implementations of the semiconductor package may include a first lead and a second lead extending from the first sidewall and a first half-etched tie bar directly coupled to the first lead. An end of the first half-etched tie bar may be exposed on the third sidewall of the semiconductor package. Implementations of the semiconductor package may also include a second half-etched tie bar directly coupled to the second lead. An end of the second half-etched tie bar may be exposed on the fourth sidewall. An end of the first lead and an end of the second lead may each be electroplated. The first die flag and the second die flag may be electrically isolated from the first lead and the second lead.