Flat Melt Solder-Plated Solar Cell Lead Wires
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Solution Overview
Problem
Conventional solar cell lead wires with rounded melt solder-plated layers suffer from instability, insufficient contact area, and position shifts during bonding, leading to cell cracking and poor soldering, especially with thin semiconductor substrates.
Innovation Solution
A solar cell lead wire with flat melt solder-plated layers on both surfaces, formed by rolling or slitting a conductive material and sandwiching it between rolls during soldering, ensuring a stable and uniform thickness, and using a Sn-based solder alloy with specific additives to enhance bonding and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rounded melt solder-plated layers are formed on the strip-shaped conductive material, then the lead wire can be easily manufactured using conventional melt plating method, but the stacked layer becomes unstable and tends to unwind when wound around a bobbin
Solution Approach 1:
The invention applies the reverse of spheroidality by deliberately creating flat surfaces instead of rounded ones. The melt solder-plated layers are formed to be flat on both upper and lower surfaces, preventing the wire from unwinding when wound around bobbins, while still using the conventional melt plating method for easy manufacturing.
2Ease of manufacture
If rounded melt solder-plated layers are used, then the manufacturing process is simple, but the contact area with air suction jig is small causing insufficient suction and falling during transfer
Solution Approach 1:
The invention uses flat surfaces instead of rounded ones to maximize the contact area between the melt solder-plated layers and the air suction jig, ensuring sufficient suction and preventing falling during transfer, while maintaining manufacturing simplicity through conventional melt plating.
3Ease of manufacture
If rounded melt solder-plated layers are formed, then the plating process is straightforward, but the contact area with frontside electrode is small causing insufficient thermal conduction and poor soldering
Solution Approach 1:
The invention forms flat melt solder-plated layers on both surfaces to maximize contact area with the frontside electrode, ensuring sufficient thermal conduction and reliable soldering, while keeping the plating process straightforward using conventional melt plating methods.
4Ease of manufacture
If rounded melt solder-plated layers are used, then the manufacturing is simple, but position shift occurs between lead wires soldered to frontside and backside electrodes causing cell cracking
Solution Approach 1:
The invention forms flat melt solder-plated layers on both the upper and lower surfaces of the strip-shaped conductive material. This ensures that when lead wires are soldered to both frontside and backside electrodes, their positions align accurately without shifting, preventing cell cracking while maintaining manufacturing simplicity.
5Quantity of substance
If thin semiconductor substrates are used to reduce cost, then the manufacturing cost decreases, but the substrates become more prone to cracking during bonding
Solution Approach 1:
The invention uses flat melt solder-plated layers on both surfaces to ensure accurate position alignment and prevent position shifts during bonding of thin semiconductor substrates. This eliminates a major cause of cell cracking, allowing the use of thinner, more cost-effective substrates without compromising reliability.
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
The solution provides a high cell cracking inhibiting effect, ensuring stable bonding, preventing position shifts, and maintaining high bonding strength, thus reducing the likelihood of semiconductor substrate cracking and improving thermal conduction.
Implementation Method 1
the melt solder-plated layers 113 are formed to be rounded from sides in width direction to the middle, by surface tension when melt solder adhering to the upper and lower surfaces 112 a and 112 b of the strip-shaped conductive material 112 is solidified
Implementation Method 2
The small contact area between the frontside electrode 104 and melt solder-plated layers 113 causes insufficient thermal conduction from semiconductor substrate 102 to melt solder-plated layer 113
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3~4
AI summary
A solar cell lead wire includes a strip-shaped conductive material formed by rolling a wire, and upper and lower melt solder-plated layers formed to be flat on upper and lower surfaces, respectively, of the strip-shaped conductive material by supplying melt solder thereto.