Surface-Mount Capacitor Seat Plate With Flux Gas Release Grooves
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Solution Overview
Problem
Existing surface-mount capacitors face issues such as voids, cracks, and solder balls due to flux gas generation during soldering, which affect reliability, and the quality of soldering cannot be visually judged.
Innovation Solution
The capacitor design includes lead terminal housing grooves with integrated auxiliary terminals and gas release grooves, widened width parts in the grooves, and soldering auxiliary parts to manage flux gas and enhance visibility of soldering quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If auxiliary terminals are provided on the bottom surface of the seat plate to increase soldering strength, then soldering strength is improved, but flux gas becomes trapped in the fillet causing voids and cracks that impair reliability
Solution Approach 1:
The auxiliary terminal is divided into multiple segments: a base portion embedded in the seat plate, a bridge portion connecting to the lead terminal, and a tip portion extending toward the circuit board. This segmentation allows flux gas to escape through the bridge portion while maintaining soldering strength through the base portion.
Solution Approach 2:
The bridge portion acts as an intermediary structure that connects the base portion and tip portion while providing a pathway for flux gas to escape. It mediates between the need for strong soldering (base portion) and the need to release flux gas (tip portion).
2Strength
If auxiliary terminals are arranged on the bottom surface of the seat plate, then soldering strength is increased, but the quality of solder fixing state cannot be visually judged from the outside
Solution Approach 1:
The auxiliary terminal is designed to extend in multiple dimensions: vertically into the seat plate for strength, horizontally as a bridge for gas escape, and outward as a tip for visual inspection. This multi-dimensional configuration allows the terminal to serve multiple functions simultaneously.
Solution Approach 2:
The auxiliary terminal may be provided with a different color or visual marker at the tip portion to facilitate visual inspection of the soldering quality. This allows operators to easily detect the state of solder fixing from the outside.
3Adaptability or versatility
If lead terminals are bent and inserted through the seat plate, then surface mounting is enabled, but solder paste is crushed by the lead terminals causing solder balls to form outside the solder land part
Solution Approach 1:
The function of crushing solder paste is extracted from the lead terminal and transferred to a dedicated structure on the circuit board (such as a retaining wall or groove). This allows the lead terminal to focus on its primary function of electrical connection while preventing solder paste displacement.
4Adaptability or versatility
If the seat plate is made of synthetic resin with lead terminal insertion holes, then surface mounting is enabled, but flux gas causes solder paste to be pushed outside forming solder balls on the solder mask or seat plate
Solution Approach 1:
The synthetic resin seat plate, which initially traps flux gas, is designed with intentional gas escape pathways through the auxiliary terminal structure. The harmful flux gas is converted into a beneficial force that flows through the designated escape route, preventing solder paste displacement and solder ball formation.
Data Source
AI summary
In a chip type capacitor formed by attaching a seat plate to a capacitor, generation of voids or cracks due to flux gas generated at the time of soldering is suppressed. When providing auxiliary terminals for increasing the soldering strength on a seat plate for chipping, which enables a lead same direction type capacitor to be surface mounted, a gas release groove, preferably formed as a slit to release flux gas generated at the time of soldering, is formed on each of the auxiliary terminals.