Batch Electroplating Flat No-Lead Package Side Leads
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Solution Overview
Problem
Conventional Flat No-Lead Packages, such as QFNs and DFNs, have unplated severed lead surfaces on their lateral side faces, which are prone to oxidation and poor solder wetting during attachment to printed circuit boards due to the lack of plating on these surfaces.
Innovation Solution
A method involving batch electroplating of severed lead surfaces on the lateral side surfaces of Flat No-Lead Packages, using an electroplating bath and a tray apparatus to apply a plating layer to the exposed lead faces, ensuring that both the bottom and side surfaces are plated, thereby preventing oxidation and improving solder wetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional Flat No-Lead Packages are manufactured with plated bottom surfaces only, then manufacturing simplicity is maintained, but the lateral side lead surfaces suffer from oxidation and poor solder wetting
Solution Approach 1:
The patent applies preliminary action by performing batch electroplating of the lateral side lead surfaces after package assembly but before final product completion. The method involves providing packages with unplated lateral surfaces and then systematically immersing them in an electroplating bath to deposit plating material on all exposed lead faces, ensuring oxidation prevention and improved solder wetting before the products reach customers.
2Reliability
If batch electroplating of lateral side surfaces is implemented, then oxidation prevention and solder wetting are improved, but process complexity increases
Solution Approach 1:
The patent merges multiple plating operations into a single batch electroplating process. Instead of plating lateral surfaces individually or adding separate plating steps for each surface, the invention combines all lateral side lead surfaces into one immersion operation where all packages are simultaneously plated in a batch process, reducing overall process complexity while achieving comprehensive coverage.
Solution Approach 2:
The electroplating bath and tray apparatus are designed with universal functionality to handle multiple packages simultaneously. The tray apparatus with multiple pockets and the conductive plate configuration allow the same equipment to process numerous packages in parallel, making the process scalable and reducing per-unit complexity.
3Manufacturing precision
If individual plating of each lead surface is performed, then plating quality is maximized, but manufacturing time and cost increase significantly
Solution Approach 1:
The patent combines multiple individual plating operations into a single batch process where numerous packages are plated simultaneously in one electroplating bath. This merging approach maintains consistent plating quality across all surfaces while dramatically increasing manufacturing throughput compared to sequential individual plating of each lead surface.
Solution Approach 2:
The batch electroplating process applies plating to all lateral side surfaces in one operation, potentially applying slightly more plating material than the absolute minimum required for each surface. This excessive action ensures complete and uniform coverage across all packages simultaneously, maintaining quality standards while achieving high productivity through batch processing.
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
The method effectively prevents oxidation and enhances the solder wetting of the lead surfaces, improving the reliability and performance of Flat No-Lead Packages by ensuring all exposed lead surfaces are plated, including those on the lateral sides.
Implementation Method 1
batch electroplating the severed unplated lead surfaces of said plurality of Flat No-Lead Packages
Data Source
AI summary
A method of making Flat No-Lead Packages with plated lead surfaces exposed on lateral faces thereof. The method includes providing a plurality of Flat No-Lead Packages having severed, unplated lead surfaces exposed on lateral faces thereof and having plated lead surfaces exposed on bottom faces thereof. The method further includes batch electroplating the severed unplated lead surfaces of the plurality of Flat No-Lead Packages.