Stepped Conductive Structure for Solder Joint Integrity
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Solution Overview
Problem
Semiconductor packages with exposed copper terminations face challenges in solderability due to oxidation, making visual inspection of solder joint integrity difficult, especially in high-reliability applications where full electrical testing is not feasible.
Innovation Solution
A semiconductor package structure with a conductive substrate featuring a stepped portion having grooves, enhancing solder joint strength and allowing for optical inspection through wettable flank plating, which improves bonding strength and facilitates easier manufacturing integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wettable flank plating is applied to improve solderability and visual inspection, then solder joint integrity can be visually verified, but manufacturing process complexity increases
Solution Approach 1:
The stepped portion is formed on the conductive element before packaging, creating a pre-prepared structure that enhances solder joint strength. This preliminary structural modification eliminates the need for additional wettable flank plating processes while achieving the same reliability improvement, thereby resolving the contradiction between reliability enhancement and manufacturing complexity
Solution Approach 2:
The invention changes the geometric parameters of the conductive element by creating a stepped portion with specific depth and width ratios. This parameter modification directly improves solder joint integrity without requiring additional plating materials or processes, thus improving reliability while avoiding increased manufacturing complexity
2Strength
If stepped portion is formed on conductive element to enhance solder joint strength, then bonding strength is improved, but manufacturing complexity increases
Solution Approach 1:
The conductive element is segmented into multiple levels or steps, creating a stepped portion that increases bonding surface area and mechanical interlocking. This segmentation approach improves bonding strength through structural modification alone, without requiring additional materials or complex assembly processes, thus resolving the contradiction between strength enhancement and manufacturing simplicity
Data Source
AI summary
An electronic package includes a substrate having a conductive element. The conductive element includes a stepped portion disposed at an end of the conductive element. In one embodiment, the conductive element is a lead. In another embodiment, the conductive element is a die pad. The stepped portion includes a first groove extending inward from a lower surface of the first conductive element, and a second groove extending further inward from the first groove towards an upper surface of the conductive element. An electronic component is connected to the conductive element. In one embodiment, a clip is used to electrically connect the electronic component to the conductive element. An encapsulant encapsulates the electronic component and a portion of the substrate such that the stepped portion is exposed outside an exterior side surface of the encapsulant. The stepped portion is configured to improve the bonding strength of the electronic package when attached to a next level of assembly.