Semiconductor Package Full Plating on Contact Side Surfaces

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Solution Overview

Problem

Conventional semiconductor packages face issues with corrosion and reduced solderability due to exposed copper surfaces on side contacts, leading to potential device failures, especially in environments with moisture or chemicals, as these surfaces oxidize and form non-metallic compounds that hinder soldering.

Innovation Solution

The semiconductor package design includes full plating on contact side surfaces, using a method that involves partial or full plating of the leadframe and molding compound to ensure continuous coverage, preventing oxidation and ensuring reliable soldering by applying a plating layer that covers both interfacing and side contact surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If singulation is performed after electroplating, then the bottom surfaces of contacts are tin plated, but the side surfaces of contacts remain exposed and susceptible to oxidation

Engineering Contradiction:

ImprovesolderabilityVSAvoidoxidation of exposed surfaces

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies plating to the side surfaces of contacts before the singulation process. By performing the plating action preliminarily, the side surfaces are protected with a corrosion-resistant layer before exposure to environmental factors during subsequent handling and storage, preventing oxidation while maintaining solderability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent divides the contact surface into distinct regions (bottom surface and side surfaces) and applies plating selectively to each. The bottom surface receives standard electroplating, while the side surfaces receive additional plating coverage, ensuring both regions are protected against oxidation with appropriate surface finishes

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If side surfaces of contacts are left exposed, then manufacturing process is simpler, but corrosion and oxidation occur leading to device failures

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoiddevice reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent merges the plating process with the existing manufacturing workflow by integrating side surface plating into the standard electroplating sequence. This is achieved through selective masking or multi-layer plating techniques that combine bottom surface and side surface plating in a unified process flow, maintaining manufacturing simplicity while ensuring comprehensive protection against corrosion and oxidation

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If oxidation occurs on contact surfaces, then solder wettability is improved initially, but contamination prevents proper soldering

Engineering Contradiction:

Improvesolder joint qualityVSAvoidcontamination on contact surfaces

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the surface parameters of contact sides by applying plating layers with controlled thickness, composition, and surface finish. This creates an optimal surface state that prevents oxidation and contamination while maintaining excellent solder wettability, ensuring reliable solder joints without the harmful effects of oxide formation

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 solution ensures quality soldering of semiconductor packages to substrates by preventing oxidation and contamination on side surfaces, enhancing the reliability and durability of solder joints.

Implementation Method 1

the contacts are plated with a lead finished material, such as matte tin (Sn), using electroplating

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS10242934B1Semiconductor package with full plating on contact side surfaces and methods thereof

Publication Date: 2019.03.26 UTAC HEADQUARTERS PTE LTD

AI summary

Embodiments of the present invention are directed to a semiconductor package with full plating on contact side surfaces. The semiconductor package includes a top surface, a bottom surface opposite the top surface, and side surfaces between the top and bottom surfaces. Contacts are located on peripheral edges of the bottom surface. Each of the contacts includes a first surface that is flush with the bottom surface and a second surface that is at one of the side surfaces. The first surface and the second surface of each of the contacts are continuously plated. Portions of an internal plating layer are exposed along the side surfaces of the semiconductor package. The semiconductor package has a molding compound at least partially encapsulating the contacts, wherein the surface of a first part of the molding compound and the surface of a second part of the molding compound have different surface texture.