Semiconductor Circuit Patterns with Protective Films for Solder Bonding

Solution Overview

Problem

Semiconductor devices with plated circuit patterns face challenges in achieving sufficient bonding strength due to reduced solder wettability, leading to voids and increased thermal resistance, which can result in reduced reliability and increased risk of short circuits.

Innovation Solution

The semiconductor device features circuit patterns with protective films on facing side surfaces, avoiding plating on bonding regions, allowing direct solder application and preventing corrosion product formation, thus enhancing bonding strength and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plating process using nickel is performed on the surfaces of the circuit patterns to suppress corrosion, then corrosion resistance is improved, but solder wettability deteriorates making it difficult to avoid production of voids inside the solder

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidsolder bonding quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The circuit pattern surface is divided into two distinct regions: a plated region for corrosion protection and a non-plated bonding region for optimal solder attachment. This segmentation allows each region to fulfill its specific function without compromising the other, resolving the contradiction between corrosion resistance and solder wettability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surface treatments are applied to different locations of the circuit pattern. The facing side surfaces receive nickel plating for corrosion resistance, while the bonding regions remain unplated to maintain solder wettability. This local differentiation enables simultaneous achievement of both corrosion protection and high-quality solder bonding.

Inventive Principle:

Principle #3Local quality

2Reliability

If plating is performed on bonding regions to prevent corrosion, then corrosion resistance is improved, but bonding strength deteriorates due to reduced solder wettability and increased thermal resistance

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidbonding strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The circuit pattern surface is divided into two distinct regions: a plated region for corrosion protection and a non-plated bonding region for optimal solder attachment. This segmentation allows each region to fulfill its specific function without compromising the other, resolving the contradiction between corrosion resistance and solder wettability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surface treatments are applied to different locations of the circuit pattern. The facing side surfaces receive nickel plating for corrosion resistance, while the bonding regions remain unplated to maintain solder wettability. This local differentiation enables simultaneous achievement of both corrosion protection and high-quality solder bonding.

Inventive Principle:

Principle #3Local quality

3Reliability

If plating is applied to all circuit pattern surfaces, then corrosion protection is improved, but manufacturing complexity increases due to additional process steps and quality control requirements

Engineering Contradiction:

Improvecorrosion protectionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The plating process is extracted from the bonding regions and applied only to the facing side surfaces. This selective application simplifies the manufacturing process by reducing the plated area, thereby decreasing process complexity and quality control requirements while maintaining adequate corrosion protection where most needed.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration improves bonding strength and reliability by preventing solder voids and short circuits, while maintaining resistance to corrosion and thermal conductivity.

Implementation Method 1

This suppresses corrosion of the circuit patterns, which prevents substances produced by corrosion (hereinafter referred to as "corrosion products") from causing short circuits between the circuit patterns

Methodology Applied

Scientific EffectCorrosion prevention:

Implementation Method 2

Cylindrical contact elements are used when attaching the external connection terminals to the circuit patterns. The external connection terminals are press-fitted into contact elements that have been bonded to the circuit patterns using solder

Methodology Applied

Scientific EffectSoldering: Soldering

Implementation Method 3

circuit patterns that have been subjected to a plating process are less wettable for solder, which makes it difficult to avoid the production of voids inside the solder

Methodology Applied

Scientific EffectWetting: Wetting

Data Source

PatentUS10699994B2Semiconductor device having bonding regions exposed through protective films provided on circuit patterns onto which components are soldered

Publication Date: 2020.06.30 FUJI ELECTRIC CO LTD

AI summary

In a semiconductor device, protective films are formed on facing side surfaces of a plurality of circuit patterns and a plating process or the like is not performed on parts aside from the side surfaces where the protective films are formed. This means that when semiconductor elements and contact elements are directly bonded via solder onto the plurality of circuit patterns, a drop-in wettability of the plurality of circuit patterns for the solder is avoided.