Back-Side Solar Cell Soldering for Gap-Free Wire Bonding
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Solution Overview
Problem
The assembly of photovoltaic (PV) cells and modules is complex due to the need for precise mechanical and electrical coupling of laminated layers and electrical connecting wires, which requires multiple steps and sequences, and existing soldering methods may not ensure full bonding without gaps, affecting the reliability and efficiency of the electrical connection.
Innovation Solution
A method involving tack soldering followed by back-side soldering using a heating zone with pressure mechanisms, such as rollers, to securely attach wires to solar cell components, ensuring both electrical and mechanical connections without gaps, by applying heat from underneath to melt solder and bond the wire to the PV cell, with a focus on targeted heating and compression to achieve full bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional soldering methods are used to attach wires to solar cells, then the process is simple, but the bonding is incomplete with gaps leading to poor electrical and mechanical connection
Solution Approach 1:
The soldering process is divided into two distinct stages: tack soldering to position the wire, and back-side soldering to complete the bonding. This segmentation allows each stage to be optimized independently, achieving complete bonding without gaps while maintaining process manageability.
Solution Approach 2:
Tack soldering is performed as a preliminary action to temporarily secure the wire in the correct position before the final back-side soldering. This preliminary positioning ensures that when the wire is heated from the backside, it bonds completely and uniformly without gaps.
2Reliability
If single-stage soldering is used, then the process is fast, but the connection reliability is insufficient leading to detachment
Solution Approach 1:
The soldering process is segmented into two sequential stages: tack soldering for positioning and back-side soldering for final bonding. This segmentation improves connection reliability by ensuring complete bonding at each stage, while the automated sequential execution minimizes additional time loss.
Solution Approach 2:
The two soldering stages are executed continuously without interruption or repositioning. The wire remains in the same position throughout, with heat applied sequentially from the front (tack) and back (final bonding) sides, maintaining continuous productive action while ensuring reliable bonding.
3Strength
If heat is applied from the front side only, then the equipment is simple, but gaps form in the bonding reducing mechanical strength
Solution Approach 1:
Instead of heating only from the front side, the process applies heat from the back side of the solar cell to melt the solder and complete the bonding. This inverted heating approach, combined with front-side tack soldering, eliminates gaps and maximizes mechanical bond strength.
Solution Approach 2:
The heating approach transitions from one-dimensional (front side only) to two-dimensional heating by applying heat from both the front (tack soldering) and back (final bonding) sides. This dimensional change ensures complete solder melting and bonding throughout the wire-solar cell interface, eliminating gaps and maximizing strength.
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 enhances the reliability and efficiency of the soldering process by ensuring full bonding without gaps, improving the electrical and mechanical connections between wires and solar cell components, thereby increasing the stability and performance of PV cell assemblies.
Implementation Method 1
applying heat to the backside of the solar cell component or a portion of the backside of the solar cell component such that the solder coating on the wire melts and the wire bonds to the solar cell component
Implementation Method 2
solder in contact with the wire melts and solders the wire to the solar cell component
Data Source
AI summary
Methods of soldering wire, such as traces or ribbon, onto single or multi-busbar solar cells. Devices constructed with such methods may also be covered. Methods may include providing a wire, such as a trace or ribbon, tack soldering the wire at one or more locations to a workpiece, such as solar cell component, and then passing the combined tacked wire and solar cell component through a heating zone where heat is applied to the backside of the solar cell component such that solder in contact with the wire melts and solders the wire to the solar cell component.