Electrode metallization method of back contact battery

Abstract

An electrode metallization method of a back contact cell belongs to the technical field of solar cells, and is characterized by comprising the following steps: printing point-shaped silver paste on the back surface of the back contact cell, and drying, sintering and curing; solder paste is printed on the silver paste and dried; printing glue between the two solder pastes; laying the back contact battery printed with the solder paste and the glue on a metal foil, and enabling the metal foil to be tightly attached to the back contact battery; heating to melt the solder paste and then solidify the solder paste to realize the welding of the back contact battery and the metal foil; meanwhile, the glue is cured; and cutting the metal foil to complete electrode metallization of the back contact battery so as to prepare the back contact battery string. According to the method, only a small amount of silver paste is used as a connecting material between the back contact battery and metal, so that silver consumption is effectively reduced, and the material cost is further reduced. Meanwhile, as the solder paste is used as a bonding material, the melting temperature is low, the process temperature of battery metallization can be effectively reduced, and the method can be applied to manufacturing of various back contact batteries and back contact laminated batteries and is wide in application range.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a method for electrode metallization of a back contact battery. Background Art

[0002] Existing back contact batteries maximize the optimization of the light trapping effect and passivation layer performance on the upper surface by eliminating the front grid line structure, enabling their photoelectric conversion efficiency to reach the highest level in the current photovoltaic industry and triggering technology layouts of many manufacturers. However, the industrialization process of this technology faces significant bottlenecks: the traditional electrode metallization process uses screen printing of silver paste followed by high-temperature sintering and curing, requiring a large amount of silver and having a high material cost, which has become a key issue restricting the industrialization of back contact batteries and seriously restricting their large-scale commercial applications.

[0003] Meanwhile, the back contact technology has the characteristic of being compatible with various substrate battery structures, and can be applied to P-type crystalline silicon substrates to form PBC batteries, or combined with N-type technologies such as TOPCon and HJT to form composite structures such as TBC and HBC. However, there are significant differences in carrier transport characteristics, surface doping concentration, and temperature sensitivity among different battery systems, resulting in multiple adaptability problems for the traditional silver paste printing process. For example, TOPCon batteries require a high-temperature sintering process to burn through the SiNx layer on the battery surface to achieve ohmic contact, while the amorphous silicon layer of HJT batteries requires low-temperature processing, and existing single metalization schemes are difficult to meet the process window requirements of different technical routes.

[0004] For the above reasons, developing a new metalization process with both low silver consumption characteristics and multi-technology compatibility has become an urgent problem to break through the industrialization bottleneck of back contact batteries. Summary of the Invention

[0005] The present invention aims to solve the above problems and provides a method for electrode metallization of a back contact battery with both low silver consumption characteristics and multi-technology compatibility.

[0006] The method for electrode metallization of the back contact battery described in the present invention includes the following steps: Print dot-shaped silver paste on the back of the back contact battery, and dry, sinter, and cure it; Print solder paste above the silver paste, with the position of the solder paste coinciding with the position of the aforementioned silver paste, and dry the solder paste; dry the solder paste before laying the metal foil to avoid the influence of the solder paste on the glue printing and ensure that the shape of the solder paste is not damaged by the extrusion of the metal foil; Print glue at the position between two aforementioned solder pastes; Lay the back contact battery printed with solder paste and glue on the metal foil, and make the metal foil closely fit with the back contact battery; Heat the back-contact battery to melt the solder paste first and then solidify it, so as to realize the welding of the back-contact battery and the metal foil; at the same time, the glue solidifies; improve the adhesion between the battery chip and the metal foil; Use a laser to cut the metal foil to separate the positive and negative electrodes of the back-contact battery, complete the electrode metallization of the back-contact battery, and obtain a back-contact battery string.

[0007] The method for electrode metallization of the back-contact battery according to the present invention includes the following steps: Print dot-shaped silver paste on the back of the back-contact battery and dry, sinter and solidify it; Print solder paste above the silver paste, and the position of the solder paste coincides with the position of the aforementioned silver paste; Print glue on the metal foil, and the position where the glue is printed corresponds to the position between the two solder pastes on the aforementioned back-contact battery; Lay the back-contact battery printed with solder paste on the metal foil printed with glue, so that the glue on the metal foil is located between the two solder pastes on the aforementioned back-contact battery, and make the metal foil and the back-contact battery fit tightly; Heat the back-contact battery to melt the solder paste first and then solidify it, so as to realize the welding of the back-contact battery and the metal foil; at the same time, the glue solidifies; improve the adhesion between the battery chip and the metal foil; Use a laser to cut the metal foil to separate the positive and negative electrodes of the back-contact battery, complete the electrode metallization of the back-contact battery, and obtain a back-contact battery string.

[0008] The method for electrode metallization of the back-contact battery according to the present invention includes the following steps: Print dot-shaped silver paste on the back of the back-contact battery and dry, sinter and solidify it; Print solder paste above the silver paste, and the position of the solder paste coincides with the position of the aforementioned silver paste; Compound the metal foil and the adhesive film, and then use a laser to cut the metal foil to obtain a patterned metal foil; Print glue on the patterned metal foil, and the position where the glue is printed corresponds to the position between the two solder pastes on the aforementioned back-contact battery; Lay the back-contact battery printed with solder paste on the patterned metal foil printed with glue, so that the glue on the patterned metal foil is located between the two solder pastes on the aforementioned back-contact battery, and make the patterned metal foil and the back-contact battery fit tightly; Heat the back-contact battery to melt the solder paste first and then solidify it, so as to realize the welding of the back-contact battery and the patterned metal foil; at the same time, the glue solidifies; improve the adhesion between the battery chip and the metal foil; complete the electrode metallization of the back-contact battery, and obtain a back-contact battery string.

[0009] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the layout of the silver paste is a dot-shaped spaced layout; The distance between every two adjacent positions of the silver paste is 5 - 500 μm .

[0010] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the thickness of the solder paste printing is 5 - 100 μm ; The melting temperature of the solder paste is ≤260°C.

[0011] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the glue is a thermosetting adhesive or a pressure-sensitive adhesive; The thickness of the glue printing is 5 - 100 μm ; The layout mode of the glue between the two solder pastes is dot-shaped or linear horizontal distribution.

[0012] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the metal foil is a pure copper foil or a copper-aluminum foil; The thickness of the metal foil is ≤100 μm ; When the metal foil is a copper-aluminum foil, the copper layer is in contact with the solder paste on the side close to the solder paste, and the aluminum layer is at the position on the side far from the solder paste.

[0013] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the implementation method for the metal foil or the patterned metal foil to be closely attached to the back-contact battery is: vacuum adsorption or physical pressing.

[0014] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, the heating method for the back-contact battery is infrared heating, hot air heating or heating plate heating.

[0015] Furthermore, in the method for electrode metallization of the back-contact battery of the present invention, when using a laser to cut the metal foil, it is divided according to the P+ region and the N+ region of the battery, and the metal foil on the surface of the battery cell and between the battery cells is cut. The metal foil connects the cut P+ regions to form a positive electrode region, the metal foil connects the cut N+ regions to form a negative electrode region, and the laser cutting part is the laser cutting region.

[0016] The electrode metallization method of the back-contact battery described in the present invention only uses a small amount of silver paste as the connection material between the back-contact battery and the metal. Most of the silver paste is replaced by metal foil, effectively saving silver consumption and thus reducing material costs. At the same time, since solder paste is used as the bonding material, the melting temperature is relatively low, which can effectively reduce the process temperature of battery metallization. It can be applied to the production of various back-contact batteries and back-contact laminated batteries, with a wide range of applications and is suitable for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a schematic structural diagram of the back-contact battery after printing silver paste according to an embodiment of the present invention; Figure 2 FIG. is a schematic structural diagram of the contact battery after printing silver paste and solder paste according to an embodiment of the present invention; Figure 3 FIG. is a schematic structural diagram of the back-contact battery after printing glue according to Embodiment 1 of the present invention; Figure 4 FIG. is a schematic structural diagram of the back-contact battery after laying metal foil according to an embodiment of the present invention; Figure 5 FIG. is a schematic structural diagram of the back-contact battery string after metallization according to an embodiment of the present invention; Figure 6 FIG. is a schematic structural diagram of the metal foil printed with glue according to Embodiment 2 of the present invention; Figure 7 FIG. is a schematic structural diagram of the patterned metal foil printed with glue according to Embodiment 3 of the present invention; Where 1-back-contact battery, 2-silver paste, 3-solder paste, 4-glue, 5-metal foil, 6-adhesive film, 7-positive electrode region, 8-negative electrode region, 9-laser cutting region. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The electrode metallization method of the back-contact battery 1 described in the present invention will be described in detail below with reference to the drawings and embodiments.

[0019] Embodiment 1 This embodiment discloses an electrode metallization method for a back-contact battery 1, which specifically includes the following steps: Step S11: Print dot-shaped silver paste 2 on the back of the back-contact battery 1 and dry, sinter and cure it; In the embodiment of the present disclosure, as Figure 1 shown, the silver paste 2 is distributed in a dot-shaped and spaced manner; the distance between two adjacent positions of the silver paste 2 is 50 μm .

[0020] Step S12: Print solder paste 3 above the silver paste 2, as Figure 2As shown, the position of the solder paste 3 coincides with the position of the silver paste 2, and the solder paste 3 is dried; before laying the metal foil 5, the solder paste 3 is dried to avoid the influence of the solder paste 3 on the printing of the glue 4, and at the same time, the shape of the solder paste 3 can be ensured not to be damaged by the extrusion of the metal foil 5.

[0021] In the embodiment of the present disclosure, the thickness of the solder paste 3 is 30 μm ; the melting temperature of the solder paste 3 is 180 °C.

[0022] Step S13: As Figure 3 shown, print the glue 4 at the position between the two aforementioned solder pastes 3; in addition to the function of fixing the metal foil 5, the glue 4 can also separate the metal foil 5 from the silicon wafer, thereby reducing the influence on the battery cell during subsequent laser use.

[0023] In the embodiment of the present disclosure, the glue 4 is a thermosetting adhesive; the thickness of the glue 4 is 30 μm . The laying method of the glue 4 is dot distribution at the middle position between the two solder pastes 3.

[0024] Step S14: As Figure 4 shown, lay the back contact battery 1 printed with the solder paste 3 and the glue 4 on the metal foil 5, and use vacuum adsorption to make the metal foil 5 closely fit with the battery; In the embodiment of the present disclosure, the material of the metal foil 5 is pure copper foil; the thickness of the metal foil 5 is 10 μm .

[0025] In specific applications, the area of the metal foil 5 is slightly smaller than the area of the battery string to facilitate positioning in the subsequent laser cutting process.

[0026] Step S15: Heat the back contact battery 1 to make the solder paste 3 melt first and then solidify, realizing the welding of the back contact battery 1 and the metal foil 5; at the same time, the glue 4 solidifies to improve the adhesion between the battery cell and the metal foil 5; In the embodiment of the present disclosure, the method of heating the battery is infrared heating.

[0027] Step S16: Use a laser to cut the metal foil 5 according to a specific pattern to separate the positive and negative electrodes of the battery, forming a positive electrode region 7 and a negative electrode region 8, and complete the electrode metallization of the back contact battery 1. As Figure 5 shown, a back contact battery 1 string is obtained. The specific pattern is divided according to the P+ region and N+ region of the battery, and the metal foil 5 on the surface of the battery cell and between the battery cells is cut. The metal foil 5 connects the cut P+ regions to form a positive electrode region 7, the metal foil 5 connects the cut N+ regions to form a negative electrode region 8, and the laser cutting part is the laser cutting region 9, and the laser cutting region 9 is located between the positive electrode region 7 and the negative electrode region 8.

[0028] Example 2 This example discloses a method for electrode metallization of a back-contact battery 1, which specifically includes the following steps: Step S21: Print dot-shaped silver paste 2 on the back of the back-contact battery 1, and dry, sinter, and cure it; In the embodiment of the present disclosure, as Figure 1 shown, the silver paste 2 is distributed in a dot-shaped interval manner; the distance between two adjacent positions of the silver paste 2 is 100 μm .

[0029] Step S22: Print solder paste 3 above the silver paste 2, as Figure 2 shown, the position of the solder paste 3 coincides with the position of the silver paste 2; In the embodiment of the present disclosure, the thickness of the solder paste 3 is 50 μm ; the melting temperature of the solder paste 3 is 200 °C.

[0030] Step S23: As Figure 6 shown, print glue 4 at the position on the metal foil 5 that is in contact with the two solder pastes 3 of the back-contact battery 1; the position where the glue 4 is printed corresponds to the position between the two solder pastes 3 on the aforementioned back-contact battery 1, and the position of the glue 4 on the metal foil 5 corresponds one-to-one to the gap position between the two solder pastes 3 on the back-contact battery 1. In addition to the function of fixing the metal foil 5, the glue 4 can also separate the metal foil 5 from the silicon wafer to reduce the influence of laser on the battery chip.

[0031] In the embodiment of the present disclosure, the glue 4 is a thermosetting adhesive; the thickness of the glue 4 is 50 μm . The layout method of the glue 4 is dot-shaped distribution at the middle position between the two solder pastes 3.

[0032] Step S24: Align and lay the back-contact battery 1 printed with solder paste 3 on the metal foil 5 printed with glue 4, as Figure 4 shown, ensure that the glue 4 is distributed between the two positions of the solder paste 3, and use vacuum adsorption to make the metal foil 5 closely fit with the battery; In the embodiment of the present disclosure, the material of the metal foil 5 is copper-aluminum foil; the thickness of the metal foil 5 is 20 μm . When the metal foil 5 is copper-aluminum foil, the copper layer is in contact with the solder paste 3 on the side close to the solder paste 3, and the aluminum layer is on the side far from the solder paste 3. Aluminum serves as a protective layer to prevent the copper foil from oxidizing.

[0033] In specific applications, the area of the metal foil 5 is slightly smaller than the area of the battery string to facilitate positioning in the subsequent laser cutting process.

[0034] Step S25: Heat the back-contact battery 1 using hot air heating so that the solder paste 3 melts first and then solidifies, realizing the welding of the back-contact battery 1 and the metal foil 5; meanwhile, the glue 4 solidifies, and the adhesion between the battery chip and the metal foil 5 is improved through the solidification of the glue 4; Step S26: Cut the metal foil 5 using a laser according to a specific pattern to separate the positive and negative electrodes of the battery, forming a positive electrode region 7 and a negative electrode region 8, and completing the electrode metallization of the back-contact battery 1. As shown in Figure 5 the figure, a back-contact battery 1 string is obtained. The laser cutting region 9 is between the positive electrode region 7 and the negative electrode region 8. The specific pattern is divided according to the P+ region and N+ region of the battery, and the metal foil 5 on the surface of the battery chip and between the battery chips is cut.

[0035] Embodiment III This embodiment discloses a method for electrode metallization of a back-contact battery 1, which specifically includes the following steps: Step S31: Print dot-shaped silver paste 2 on the back of the back-contact battery 1, and dry, sinter and solidify it; In the embodiment of the present disclosure, as shown in Figure 1 the figure, the silver paste 2 is distributed in a dot-shaped and spaced manner; the distance between two adjacent positions of the silver paste 2 is 60 μm .

[0036] Step S32: Print solder paste 3 above the silver paste 2. As shown in Figure 2 the figure, the position of the solder paste 3 coincides with the position of the silver paste 2; In the embodiment of the present disclosure, the thickness of the solder paste 3 is 40 μm ; the melting temperature of the solder paste 3 is 150 °C.

[0037] Step S33: As shown in Figure 7 the figure, compound the metal foil 5 and the adhesive film 6, and then cut the metal foil 5 using a laser according to a specific pattern to form the metal foil 5 corresponding to the positive electrode region 7 and the negative electrode region 8, complete the patterning of the metal foil 5, and obtain the patterned metal foil 5; the specific pattern is divided according to the P+ region and N+ region of the battery. The metal foil 5 connects the cut P+ regions to form the positive electrode region 7, the metal foil 5 connects the cut N+ regions to form the negative electrode region 8, and the laser cutting part is the laser cutting region 9, and the laser cutting region 9 is located between the positive electrode region 7 and the negative electrode region 8.

[0038] Step S34: Print glue 4 at the position on the above-mentioned patterned metal foil 5 that is in contact with the two solder pastes 3 of the back-contact battery 1; the position of the glue 4 on the patterned metal foil 5 corresponds one-to-one with the gap position between the two solder pastes 3 on the back-contact battery 1.

[0039] In the embodiment of the present disclosure, the glue 4 is a pressure-sensitive adhesive; the thickness of the glue 4 is 40 μm . The glue 4 is arranged in a linear horizontal distribution at the middle position between the two solders 3.

[0040] Step S35: Align and lay the back-contact battery 1 printed with the solder 3 on the patterned metal foil 5 printed with the glue 4, ensure that the glue 4 is distributed between the two solder 3 positions, and use physical pressing to closely fit the metal foil 5 with the battery; In the embodiment of the present disclosure, the material of the metal foil 5 is pure copper foil; the thickness of the metal foil 5 is 60 μm .

[0041] Step S36: Heat the back-contact battery 1 by means of infrared heating, hot air heating or heating plate heating, so that the solder 3 melts first and then solidifies to realize the welding of the back-contact battery 1 and the metal foil 5; at the same time, the glue 4 solidifies, and the adhesion between the battery chip and the metal foil 5 is improved through the solidification of the glue 4; complete the electrode metallization of the back-contact battery 1, as Figure 5 shown, to obtain a back-contact battery 1 string.

Claims

1. A method for metallizing an electrode of a back contact battery, characterized in that include: Printing dot-shaped silver paste on the back of the back contact battery, and drying and sintering to solidify; Printing solder paste on the silver paste, and drying the solder paste; Print glue between the two aforementioned solder pastes; Laying the back contact battery printed with solder paste and glue on the metal foil, and making the metal foil and the back contact battery fit tightly; The back contact battery is heated to melt the solder paste first and then solidify, so as to realize the welding between the back contact battery and the metal foil; at the same time, the glue is solidified; The metal foil is cut by laser to separate the positive and negative electrodes of the back contact battery, complete the electrode metallization of the back contact battery, and produce a back contact battery string.

2. A method for metallizing an electrode of a back contact battery, characterized in that include: Printing dot-shaped silver paste on the back of the back contact battery, and drying and sintering to solidify; printing solder paste on the silver paste; Printing glue on the metal foil, the position of the printed glue corresponds to the position between the two solder pastes on the aforementioned back contact battery; Laying the back contact battery printed with solder paste on the metal foil printed with glue, so that the glue on the metal foil is located between the two solder pastes on the back contact battery, and the metal foil and the back contact battery are closely attached; The back contact battery is heated to melt the solder paste first and then solidify, so as to realize the welding between the back contact battery and the metal foil; at the same time, the glue is solidified; The metal foil is cut by laser to separate the positive and negative electrodes of the back contact battery, complete the electrode metallization of the back contact battery, and produce a back contact battery string.

3. A method for metallizing an electrode of a back contact battery, characterized in that include: Printing dot-shaped silver paste on the back of the back contact battery, and drying and sintering to solidify; printing solder paste on the silver paste; Compounding the metal foil with the adhesive film, and then cutting the metal foil with a laser to obtain a patterned metal foil; Printing glue on the patterned metal foil, the position of the printed glue corresponding to the position between the two solder pastes on the aforementioned back contact battery; Laying the back contact battery printed with solder paste on the patterned metal foil printed with glue, so that the glue on the patterned metal foil is located between the two solder pastes on the back contact battery, and the patterned metal foil and the back contact battery are closely attached; The back contact battery is heated to melt the solder paste first and then solidify, thereby realizing welding of the back contact battery and the patterned metal foil; at the same time, the glue is solidified; the electrode metallization of the back contact battery is completed, and a back contact battery string is obtained.

4. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The layout of the silver paste is a dot-like spaced layout; The distance between each two adjacent silver pastes is 5-500 μm .

5. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The thickness of the solder paste printing is 5-100 μm ; The melting temperature of the solder paste is ≤260°C.

6. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The glue is a thermosetting adhesive or a pressure-sensitive adhesive; The thickness of the glue printing is 5-100 μm ; The glue is arranged between the two solder pastes in a dot-shaped or line-shaped horizontal distribution.

7. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The metal foil is pure copper foil or copper-aluminum foil; The thickness of the metal foil is ≤100 μm ; When the metal foil is copper-aluminum foil, the copper layer is in contact with the solder paste at a side close to the solder paste, and the aluminum layer is at a side away from the solder paste.

8. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The metal foil or patterned metal foil is tightly attached to the back contact battery by vacuum adsorption or physical compression.

9. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: The back contact battery is heated by infrared heating, hot air heating or heating plate heating.

10. The electrode metallization method of the back contact battery according to claim 1, 2 or 3, characterized in that: When the metal foil is cut by laser, it is divided according to the P+ area and N+ area of ​​the battery, and the metal foil on the surface of the battery cell and between the battery cells are cut.

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