Slit-Hole Lead Plate Soldering to Prevent Solder Runoff
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Solution Overview
Problem
The existing circuit board soldering structure faces issues with molten solder flowing down from the slit hole, causing heat damage and short-circuiting, due to inadequate temperature maintenance and alloy layer formation between the lead plate and the metal film.
Innovation Solution
An elastically-deformable metal lead plate with a bent section is inserted into the slit hole, narrowing the gap and maintaining molten solder at a high temperature to form a reliable alloy layer, preventing it from flowing down by elastic pressure on the slit hole surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If molten solder is caused to flow into the gap for soldering, then soldering connection is achieved, but molten solder flows down from the gap causing heat damage and short-circuiting
Solution Approach 1:
The patent introduces a flux-containing layer as an intermediary substance between the molten solder and the gap. This flux layer acts as a mediator that controls solder flow behavior, allowing the solder to wet and connect to the metal film while preventing uncontrolled downward flow. The flux creates a controlled interface that enables reliable soldering without the harmful effects of solder dripping.
Solution Approach 2:
The patent changes the physical and chemical parameters of the soldering environment by introducing flux with specific properties (viscosity, surface tension, reactivity). These parameter changes modify the solder's flow characteristics, enabling it to maintain connection reliability through improved wetting while preventing harmful flow downward by controlling the solder's rheological behavior at the joint interface.
2Reliability
If molten solder temperature is maintained high for alloy layer formation, then reliable soldering is achieved, but solder fluidity increases causing flow down
Solution Approach 1:
The flux layer serves as an intermediary that decouples the relationship between temperature and fluidity. It allows the solder to be maintained at high temperature for adequate alloy layer formation while the flux's viscous properties and surface tension control prevent the solder from flowing down, effectively mediating between the conflicting requirements of temperature maintenance and flow control.
Solution Approach 2:
The patent converts the potentially harmful effect of increased solder fluidity at high temperature into a beneficial effect. By using flux to control the interface properties, the high fluidity that would normally cause flow down is instead harnessed to improve wetting and alloy layer formation, while the flux's restraining effect prevents actual solder dripping. The harmful fluidity is transformed into beneficial wetting capability.
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 configuration ensures reliable soldering by preventing molten solder from flowing down while maintaining it at a high temperature for effective alloy layer formation, ensuring stable electrical connections.
Implementation Method 1
The lead plate is made of an elastically-deformable metal plate thinner than an opening width of the slit hole. The lead plate includes an insertion section inserted into the slit hole. The insertion section includes a bent section approaching from one of opposing inner surfaces of the slit hole toward another of the opposing inner surfaces of the slit hole.
Implementation Method 2
It is important for the molten solder having flowed into the gap to be cooled and strongly brought into close contact with the surfaces of both the lead plate and the metal film to achieve electrical connection. This state is not achieved by simply causing the molten solder to flow into the gap for soldering, and requires the molten solder having flown into the gap to heat both the surfaces of the lead plate and the metal film to a predetermined temperature.
Implementation Method 3
soldering forms an alloy layer at an interface between solder and metal and strongly joins the solder to the metal
Implementation Method 4
The joining in this state requires the molten solder having flown into the gap for soldering to be maintained at a temperature higher than a temperature at which the alloy layer is formed.
Data Source
AI summary
A circuit board soldering structure includes lead a plate inserted into a slit hole of a circuit board and soldered to a conductive pattern provided along the slit hole. The lead plate is made of an elastically-deformable metal plate thinner than an opening width (W) of slit hole. The lead plate includes insertion section inserted into the slit hole. The insertion section includes a bent section approaching from one of opposing inner surfaces of the slit hole facing each other toward another of the opposing inner surfaces of the slit hole. The bent section is disposed in the slit hole. The insertion section has both surfaces that are close to or contact corresponding opposing inner surfaces of the slit hole to solder the insertion section to the conductive pattern.