Lead Built-in Circuit Package with Single-Side Resin Molding
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Solution Overview
Problem
The existing axial lead type circuit packages for diodes and resistors require significant equipment investment and production costs due to the need for multiple molds and cutting dies, and result in excess lead length issues during mounting, which complicates thermal stress management and size flexibility.
Innovation Solution
A lead built-in type circuit package where either the right or back surface of a lead frame serves as the top surface, with a first molded resin covering the inner lead and a second resin portion on the outer lead sides, allowing for single-side resin molding and adjustable lead length through dicing, eliminating the need for upper and lower molds and cutting dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple molds and cutting dies are used for producing axial lead type circuit packages according to specifications, then manufacturing precision and adaptability are improved, but equipment investment and production cost increase
Solution Approach 1:
The patent applies a universal mold structure that can produce different package sizes by simply changing the lead frame specifications rather than requiring dedicated molds for each size. The mold includes a movable mold and fixed mold that can accommodate various lead frame dimensions, making the equipment versatile for producing multiple package types (e.g., 1206, 0805, 0603 sizes) with the same equipment, thereby reducing equipment investment while maintaining adaptability.
Solution Approach 2:
The patent changes the parameter of lead frame length to achieve different package sizes and lead lengths without requiring different molds or cutting dies. By producing lead frames with varying lengths in the same mold and subsequently cutting them to appropriate lengths, the system achieves size adaptability while simplifying equipment requirements.
2Adaptability or versatility
If lead frames with long outer leads are used for mounting on electric circuits, then adaptability to different mounting positions is improved, but lead waste increases due to excess length
Solution Approach 1:
The patent performs preliminary cutting of the lead frame to appropriate lengths during the molding process itself, rather than using excessively long leads and cutting them later during assembly. The movable mold moves to a predetermined position to cut the lead frame, removing excess lead material before the packaging is completed, thereby reducing lead waste while maintaining the necessary lead length for mounting flexibility.
Solution Approach 2:
The patent replaces the traditional mechanical cutting die system with an integrated mold-based cutting mechanism. Instead of using separate cutting dies to trim leads after molding, the mold itself performs the cutting function by moving to a predetermined position, combining the molding and cutting operations into a single process that reduces waste and simplifies equipment.
3Ease of operation
If axial lead type packages are used for mounting electronic parts, then ease of operation for welding is improved, but thermal stress damage to semiconductor elements increases due to welding heat
Solution Approach 1:
The patent uses a molded resin package body that provides thermal insulation between the welding area and the semiconductor element. The resin material acts as a thermal barrier, protecting the semiconductor from excessive heat during the welding process while still allowing mechanical welding operations to be performed easily on the exposed lead portions.
Data Source
AI summary
A circuit package having an inner lead, an outer lead and a circuit element is provided, in which the circuit element is connected a first surface of the inner lead. The circuit package has a first molded resin portion and second molded resin portions. The first molded resin portion is formed from a second surface, opposite to the first surface, of the inner lead toward the first surface inner lead embedding the inner lead and the circuit element. And the second molded resin portions are formed on side portions of the outer lead excluding the first and second surfaces of the outer lead.