Lead Pin Wiring Board Anchor Effect for Bonding Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wiring boards with lead pins face challenges in achieving sufficient bonding strength, particularly as the diameter of lead pins decreases with increasing pin density, leading to inadequate bonding strength between the lead pins and the wiring board.
Innovation Solution
The solution involves forming lead pins with a head portion larger in diameter than the shaft portion, bonding these to connection pads using a conductive material, and resin-sealing the wiring board to enhance bonding strength through an anchor effect, where the head portions are partially buried in resin, either using a sealing jig or a resin sealing apparatus, and filling recessed holes with a second resin to secure the lead pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diameter of lead pins is reduced to increase pin density, then the number of pins per unit area increases, but the bonding strength between lead pins and wiring board decreases
Solution Approach 1:
The patent transitions from two-dimensional bonding (flat head portion on connection pad) to three-dimensional bonding by forming a protruding portion that extends vertically from the head portion into the resin sealant. This vertical dimension increases the bonding area and creates an anchor effect, allowing sufficient bonding strength even with reduced pin diameter for higher pin density.
Solution Approach 2:
The patent uses a composite structure combining the lead pin material (metal), the conductive material (solder), and the resin sealant. The protruding portion of the lead pin embeds into the resin sealant, creating a composite bonding system that combines solder bonding strength with mechanical anchoring in the resin, thereby enhancing overall bonding strength despite smaller pin diameters.
2Strength
If the head portion diameter is increased to ensure bonding area, then bonding strength improves, but the pin density decreases
Solution Approach 1:
Instead of increasing the horizontal diameter of the head portion, the patent extends the bonding structure vertically by forming a protruding portion that protrudes from the head portion in the thickness direction. This allows the bonding area to increase in the vertical dimension while maintaining a compact horizontal footprint, enabling high pin density without sacrificing bonding strength.
3Device complexity
If conventional lead pins with flat head portions are used, then the structure is simple, but sufficient bonding strength cannot be achieved with small diameter pins
Solution Approach 1:
The protruding portion is formed as an integral part of the lead pin structure during the lead pin formation process, before the bonding and resin sealing steps. This preliminary formation of the anchoring structure ensures that when the lead pin is bonded to the connection pad and subsequently sealed with resin, the protruding portion automatically creates the anchor effect without requiring additional processing steps.
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 method significantly enhances the bonding strength of lead pins to the wiring board, ensuring reliable connections even with smaller diameter pins, by increasing the bonding area and utilizing the anchor effect of the resin to improve pull strength.
Implementation Method 1
bonding the lead pins to connection pads formed on a wiring board by using a bonding conductive material such as a solder
Implementation Method 2
resin-sealing the wiring board to enhance bonding strength through an anchor effect, where the head portions are partially buried in resin
Data Source
AI summary
A wiring board with lead pins includes: connection pads formed on a wiring board, and lead pins bonded through a conductive material to the connection pads, wherein each of the lead pins has a head portion that is formed in one end of a shaft portion to be larger in diameter than the shaft portion, the head portions are bonded to the connection pads by the conductive material, a face of the wiring board on which the connection pads are formed is resin-sealed by a first resin to be thicker than the head portions, except portions to which the head portions are bonded, and sides of faces of the head portions to which the shaft portions are connected are sealed to be in close contact with the first resin by a second resin.