SMD Diode Runner Body Molding and Tin Dipping
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Solution Overview
Problem
The existing production process for surface mount (SMD) diodes is inefficient, wasteful, and environmentally harmful due to low copper and epoxy resin utilization, and the tin electroplating process emits toxic gases and waste water, making it difficult to weld the diodes to modern circuit boards and posing health risks.
Innovation Solution
The SMD diode design incorporates a runner body with copper pins bent at 90° and a tin-dipped layer, allowing for direct welding to circuit boards without electroplating, using an elongated runner groove for molding and high epoxy resin utilization, reducing waste and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tin electroplating is used to plate the positive and negative pins, then the welding process becomes troublesome and time-consuming, but the production process emits toxic gases, waste water and metal ions causing environmental pollution
Solution Approach 1:
The patent extracts and removes the harmful electroplating process from the manufacturing workflow. Instead of electroplating tin onto the pins, the invention uses a tin alloy material (containing 5-15% tin) directly in the molding process, eliminating the separate electroplating step and its associated toxic emissions while maintaining welding capability
Solution Approach 2:
The patent replaces the chemical electroplating process with a mechanical/molding approach. The tin alloy is incorporated into the plastic packaging material during injection molding, allowing the pins to acquire their tin coating through the molding process itself rather than through chemical electroplating
2Productivity
If conventional molding process is used with epoxy resin injected through the middle runner, then the mold occupies large space and molding efficiency is poor, but copper utilization rate is only 10-15% and epoxy resin utilization is less than 30%
Solution Approach 1:
The patent inverts the conventional molding approach. Instead of injecting epoxy resin through a middle runner that requires the mold to occupy large space, the invention uses an elongated runner groove design where the resin flows along the length of the component, reducing mold footprint and improving material utilization
Solution Approach 2:
The patent transitions from a conventional centralized injection approach to a linear/elongated injection path. The runner groove extends along the length of the component, changing the dimensional approach to material delivery and enabling better space utilization and reduced waste
3Ease of manufacture
If copper sheets are cut off after molding, then production costs increase, but copper utilization rate is only 10-15%
Solution Approach 1:
The patent applies preliminary action by pre-bending the copper pins to their final configuration before molding. This eliminates the need for post-molding cutting and bending operations, reducing both production costs and copper waste while maintaining manufacturing ease
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 approach enhances production efficiency, minimizes copper and epoxy resin waste, eliminates toxic emissions during welding, and promotes environmental protection by achieving 100% copper utilization and over 90% epoxy resin efficiency, while ensuring easier and safer diode attachment to circuit boards.
Implementation Method 1
a tin-dipped layer having a cambered surface may be provided on the part of positive pin 2 and negative pin 3 extending out of the plastic-packaged body 4 under surface tension effect of the liquid tin
Data Source
AI summary
A surface mount (SMD) diode taking a runner as the body and a manufacturing method thereof are described. An elongated runner groove is adopted to cure and package groups of diode chips arranged side by side and corresponding copper pins thereon, with the utilization rate of epoxy resin up to 90% or more. The use cost of epoxy resin is thus reduced, and environmental pollution is also reduced.