CN-122007700-A - Preactivation welding method and system for photovoltaic solder strip

Abstract

The invention provides a pre-activation welding method and system for a photovoltaic welding strip, and belongs to the technical field of surface treatment. The method comprises the steps of adding an online preactivation step after unreeling a welding strip and before spraying soldering flux, mixing organic acid steam with the concentration of 100-500 ppm with inert carrier gas, uniformly spraying the mixture onto the surface of the welding strip through a fan-shaped atomizing nozzle, and simultaneously accurately maintaining the surface temperature of the welding strip at 90-110 ℃ for 1-2 seconds by using an independent temperature control unit, so that the acid steam and an oxide layer undergo a reduction reaction to generate a thermally decomposable metal organic acid salt, and realizing in-situ regeneration of the surface. The system is a modularized device and comprises gas mixing, atomizing and spraying, closed-loop temperature control and safe discharge units, and can be directly arranged on a series welding machine. The invention solves the problem of whole-piece blank welding caused by sealed corrosion and oxidation of the inner layer of the welding strip.

Inventors

• LI MINGQIU
• Ju Qijie

Assignees

• 常州九天新能源科技股份有限公司

Dates

Publication Date

20260512

Application Date

20260413

Claims (6)

1. 1. The preactivation welding method for the photovoltaic solder strip is characterized by comprising the following steps of: step a, on a continuous advancing path of a welding strip, before a soldering flux spraying station, mixing volatile organic acid steam and inert carrier gas in proportion by a mass flow controller to form activated gas with the concentration of organic acid of 100-500 ppm; Step b, uniformly spraying the activating gas to the surface of the welding strip in a mode of covering the full width of the welding strip through a fan-shaped atomizing nozzle (21) fixedly arranged; c, synchronously heating the sprayed area of the welding strip through an independent temperature control unit, forming closed-loop control by utilizing feedback of a temperature sensor (32), accurately maintaining the surface temperature of the welding strip within the range of 90-110 ℃, and continuously processing for 1-2 seconds; Step d, automatically matching and calling a preset process formula to set the gas concentration in the step a and the temperature value in the step c according to the oxidation risk level judged by the welding strip batch information; And e, finally, enabling the welding strip subjected to the pre-activation treatment in the step a to enter a subsequent station, and sequentially spraying soldering flux and welding by heating.
2. 2. The method according to claim 1, wherein in the step a, the volatile organic acid vapor is formic acid or acetic acid, the concentration is 300-500ppm, and the inert carrier gas is nitrogen.
3. 3. The method according to claim 1, wherein in the step C, the independent temperature control unit is used for realizing heating by multiplexing an original preheating platform of the series welding machine or by an additionally installed infrared heater, and the closed loop control is used for controlling the temperature fluctuation within +/-2 ℃.
4. 4. The pre-activation welding system for a photovoltaic solder strip of 1-3, wherein the system is integrated between a solder strip unreeling station and a soldering flux spraying station of a series welder as an independent functional module, comprises: The gas supply and precision mixing unit (1) comprises an organic acid storage tank (11), an inert gas source (12), a dual-channel mass flow controller (13) and a static mixing cavity (14) and is used for generating and conveying organic acid mixed gas with stable concentration; The atomizing and spraying unit (2) comprises at least one fan-shaped atomizing nozzle (21) and a direction-adjustable mounting bracket (22), wherein the bracket is mounted by adapting to the existing structure of the series welding machine, so that the nozzle is aligned to the surface of a welding strip; The local micro-area closed-loop temperature control unit (3) comprises an independent heater (31), a temperature sensor (32) and a PID controller (33) and is used for performing accurate temperature control on the activated micro-area of the welding belt independent of the series welding machine; an instant safety purification unit (4) comprising an exhaust hood (41) arranged above the injection point for creating a local negative pressure and for instant evacuation of residual gases.
5. 5. The pre-activation welding system for a photovoltaic solder strip according to claim 4, wherein in the local micro-area closed loop temperature control unit (3), the independent heater (31) is an infrared heating pipe or a hot air nozzle with power not more than 50W, the temperature sensor (32) is an infrared thermometer, and the PID controller (33) dynamically adjusts the heater power according to a sensor feedback signal.
6. 6. The photovoltaic solder strip preactivation welding system according to claim 4, further comprising a parameter adaptive control unit (5) in which a plurality of sets of process recipes corresponding to different solder strip oxidation risk levels are stored, and which is capable of receiving an external level signal, and automatically driving the gas supply and precision mixing unit (1) and the local micro-area closed loop temperature control unit (3) to execute corresponding parameters.

Description

Preactivation welding method and system for photovoltaic solder strip Technical Field The invention relates to the technical field of surface treatment, in particular to a preactivation welding method and a preactivation welding system for a photovoltaic welding strip. Background In the automatic series welding production of photovoltaic modules, a tin-lead alloy welding strip is generally adopted to connect a battery piece main grid, the weldability of the surface of the welding strip directly determines the connection resistance and long-term reliability, which are key factors influencing the power output and quality preservation of the modules, however, the surface of the welding strip is extremely easy to oxidize in the storage, transportation and workshop storage processes after tinning, a compact oxide layer mainly composed of SnO 2, pbO and oxyhydroxide thereof is formed, the problem is particularly serious in a high-temperature and high-humidity environment, and for the inner layer part of the welding strip coil, a more intractable airtight corrosion oxide layer is formed due to the airtight state, the structure is loose, the thickness is uneven, the welding strip is rich in hydroxyl groups, and the chemical reaction activity is low. The current industry has defects in mainstream solutions of oxidation problems of welding strips, such as spraying rosin-based or organic acid type soldering flux at the moment of welding, the method has fundamental contradiction under the standard high-speed production beat, the activity of the soldering flux is limited in order to protect the battery piece from corrosion, the limited activity and the extremely short acting time are not enough to reduce the formed compact oxide layer, especially the formed compact oxide layer is almost ineffective, which directly causes batch whole-piece blank welding defects, namely the welding strips and the main grid are not combined in any metallurgical way to fall off integrally, and the yield loss is serious; the method also can be used for passively protecting and replacing materials, and the method requires a welding strip supplier to adopt vacuum or nitrogen-filled packaging, which obviously increases the purchase cost, and the method also increases the material cost by replacing the welding strip with a Sn63Pb37 eutectic welding strip with slightly better oxidation resistance, and the two methods are cost transfer, do not technically solve the problem and can not process oxidized stock welding strips. The method sacrifices a process window, easily causes the risk of hidden cracking and hot spots of the battery piece to be increased, and has high equipment reconstruction cost and long period, thereby influencing the production continuity. Therefore, there is a need in the art for a method and system for on-line and in-situ chemical reduction of the oxide layer on the surface of a solder strip to restore the solder strip to a state close to factory without interrupting production and changing the performance of the solder strip body. Disclosure of Invention The invention aims to thoroughly solve the technical bottleneck and provides an innovative photovoltaic solder strip preactivation welding method. The method is characterized in that on-line and in-situ chemical reduction of an oxide layer on the surface of the welding strip is finished immediately before welding on the premise of not interrupting production and not changing the performance of the welding strip body, so that the welding strip is restored to be close to the weldability in a factory state. In order to achieve the above purpose, the present invention provides the following technical solutions: A pre-activation welding method of a photovoltaic solder strip comprises the following steps: step a, on a continuous advancing path of a welding strip, before a soldering flux spraying station, mixing volatile organic acid steam and inert carrier gas in proportion by a mass flow controller to form activated gas with the concentration of organic acid of 100-500 ppm; step b, uniformly spraying the activating gas to the surface of the welding strip in a mode of covering the full width of the welding strip through a fan-shaped atomizing nozzle which is fixedly arranged; c, synchronously heating the sprayed area of the welding strip through an independent temperature control unit, forming closed-loop control by utilizing feedback of a temperature sensor, accurately maintaining the surface temperature of the welding strip within the range of 90-110 ℃, and continuously processing for 1-2 seconds; Step d, automatically matching and calling a preset process formula to set the gas concentration in the step a and the temperature value in the step c according to the oxidation risk level judged by the welding strip batch information; And e, finally, enabling the welding strip subjected to the pre-activation treatment in the step a to enter a subsequent station, and sequentially spray