No-Lead Semiconductor Package Electroplating for Sidewall Wetting
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Solution Overview
Problem
Traditional QFN packages face challenges in determining soldering quality due to non-wetting defects on lateral surfaces and complex manufacturing processes, leading to unreliable electrical connections and increased inspection time and costs.
Innovation Solution
A manufacturing method for a no-lead semiconductor package component involving a specific cutting and electroplating process that ensures complete coverage of metal contacts with solder material, maintaining electrical connectivity and simplifying the inspection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If step cutting is performed on the lead frame to enable electroplating on lateral surfaces, then the creepage function of metal contacts is improved, but the full creepage height cannot be realized and air may remain on step portions
Solution Approach 1:
The patent applies preliminary action by performing the cutting operation after the electroplating process rather than before. The lead frame is first electroplated with solder material to achieve complete coverage and full creepage height, then cut to separate individual components. This sequence ensures that the lateral surfaces are fully coated with solder material before cutting, eliminating the step portions that would trap air and ensuring complete wetting of metal contacts.
2Reliability
If full cutting is performed on the lead frame to expose lateral surfaces, then metal contacts can be covered by solder material, but the number of connection bars must depend on the number of leads making the process complex
Solution Approach 1:
The patent applies merging by combining multiple lead frames into a single integrated structure that shares common connection bars. Instead of having separate connection bars for each lead, the design merges adjacent leads to share connection infrastructure, reducing the total number of connection bars required. This simplifies the manufacturing process while ensuring complete electroplating coverage of all lateral surfaces and metal contacts.
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
Enhances soldering quality, improves electrical conductivity, and reduces inspection time and costs by ensuring complete electroplating coverage and maintaining electrical connections, while providing ESD protection.
Implementation Method 1
applying a solderable metal layer on all of the plurality of metal contacts that are exposed by an electroplating process
Data Source
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AI summary
A manufacturing method of a no-lead semiconductor package component (200) including: mounting a chip (101) on a metal frame (102), wherein the metal frame includes two short metal connecting bars (202) to allow the top metal contact (203) and the bottom metal contact (204) to be electrically connected to the two X-direction connecting metal bars (205), respectively, thereby performing bonding or soldering; performing a plastic package molding; cutting the Y-direction connecting bar (201) by a first cutter (301) so as to expose an entire of lateral surfaces of the plurality of metal contacts; applying a solderable metal layer (400a) on all of the plurality of metal contacts that are exposed by an electroplating process; and cutting off the plastic molding material (105) by a second cutter (302) whose diameter is smaller than a diameter of the first cutter to obtain a single semiconductor package component (200).