TWI724631B - Ultrasonic soldering apparatus and ultrasonic soldering method - Google Patents

Abstract

The present invention relates to an ultrasonic soldering apparatus and an ultrasonic soldering method, and an objective of the present invention is to form a uniform, thin, and strong solder layer without thermal damage or ultrasonic damage to a substrate film.

The composition of the ultrasonic soldering apparatus of the present invention is composed of a tip heating device, an ultrasonic oscillator, a solder preheating device, a solder slide device, and a tip moving device; wherein, a pre-heated thread-like solder is melted at the tip part and ultrasonic waves are applied to remove the adhering matter from the adjacent substrate part, and the molten solder is attached to the substrate part and soldered.

Description

Ultrasonic welding device and ultrasonic welding method

The present invention relates to an ultrasonic welding device and an ultrasonic welding method for welding a substrate or a film portion formed on the substrate.

In the past, solar cells consisted of the following elements: N-type/P-type silicon substrate, which converts sunlight energy into electrical energy; silicon nitride film, which is an insulator thin film on the surface of the silicon substrate; finger-shaped The finger electrode is to take out the electrons generated in the silicon substrate; the bus bar electrode is to collect the electrons taken out by the finger electrode; the lead wire electrode is to take out the electrons collected in the bus bar electrode to the outside.

Furthermore, on the back of the solar cell, a wire is welded to an aluminum electrode formed by coating aluminum paste.

At this time, on the back of the solar cell, the lead wire is welded to the aluminum electrode. However, its strength is weak. It is tied to the opening of the aluminum electrode and the silver paste is coated/sintered to weld the wire to the silver paste portion to ensure the strength.

As mentioned above, for example, welding a wire to the aluminum electrode formed on the back of the solar cell, opening a hole in the aluminum electrode and applying/sintering silver paste there, and then welding the wire to the silver paste part, the wire cannot be obtained. Sufficient tensile strength, the need for extra steps such as coating/sintering of silver paste, and so on, lead to the problem of high cost.

Therefore, it is desirable to solder the wires to the substrate (silicon substrate) constituting the solar cell or the aluminum electrode formed on the substrate in a firm and low-cost manner.

The inventors of the present invention increased the cross-sectional area and heat capacity of the soldering iron tip to reduce the heating temperature of the soldering iron tip and reduce the thermal damage to the substrate. Moreover, the ultrasonic conduction is good and the ultrasonic output is reduced, and the substrate is removed. The attachments on the substrate form a thin and uniform solder layer, so as to realize the formation of a uniform and thin solder layer without causing damage to the film of the substrate.

Therefore, the present invention is an ultrasonic welding device for welding a substrate or a part of a film formed on a substrate, and includes the following devices: a substrate preparation heating device, which preheats the substrate to be welded or the substrate with the film formed on it To a predetermined temperature, the predetermined temperature is lower than the melting temperature of the solder; the soldering iron tip heating device adjusts the soldering iron tip portion close to the portion of the substrate that is prepared to be heated to a predetermined temperature by the substrate preparation heating device to a predetermined temperature. The predetermined temperature is the one that will melt the supplied solder under the state of applying ultrasonic waves; the ultrasonic oscillation device is to supply ultrasonic waves to the soldering iron tip heated by the aforementioned soldering iron tip heating device; the solder preparation heating device is to supply The wire solder to the tip of the soldering iron is prepared to be heated to a temperature lower than the temperature at which the wire solder will melt; The solder sliding device is a device that adjusts the speed at which the wire-shaped solder that has been preheated by the solder preparation heating device is supplied to the heated soldering iron tip part; and the soldering iron tip moving device is a device that heats a portion close to the substrate at a predetermined speed. The soldering iron tip supplies the wire-shaped solder while moving the soldering iron tip in the welding direction at a predetermined speed. The aforementioned wire-shaped solder is preheated by the solder sliding device; and the ultrasonic soldering device is constructed in the following way: The heated wire solder is melted by the tip of the soldering iron and ultrasonic waves are applied to remove the attached matter on the approaching board portion, and the molten solder is attached and soldered to the board portion.

At this time, regarding the shape of the soldering iron tip, the length of the moving direction of the soldering iron tip is longer than the width of the soldering iron tip, and the cross-sectional area and heat capacity are increased to improve the heat conduction to the substrate and reduce the temperature of the soldering iron tip to reduce the resistance to the substrate. Thermal damage to the film on the substrate or the film in the substrate.

Furthermore, regarding the shape of the soldering iron tip, the length of the moving direction of the soldering iron tip is longer than the width of the moving direction of the soldering iron tip, and the cross-sectional area is increased to improve the transmission of ultrasonic waves to the substrate and improve the removal and reduction of adhesions. Ultrasonic oscillation output to reduce the ultrasonic damage to the film on the substrate or the film in the substrate.

Furthermore, the ultrasonic oscillation output is set to 2W to 6W, preferably 2W.

Furthermore, regarding the shape of the soldering iron tip part, it is set in the following way: set the length of the soldering iron tip's moving direction to 3 to 6 times the width of the soldering iron tip's moving direction, and match the fluctuations of the substrate's soldering iron tip moving direction The length of the cycle to form a uniform thickness of the solder layer.

Furthermore, it is performed to increase or decrease the cross-sectional area of the preheated wire-shaped solder so that the thickness of the solder to the substrate can be adjusted as thin as possible.

In addition, it was performed so that the supply speed of the preheated wire-shaped solder was made the same as the moving speed of the aforementioned soldering iron tip.

Furthermore, the supply speed of the preheated wire solder and the moving speed of the soldering iron tip are set in the following way: the former is faster than the latter and the amount of molten solder is increased to increase the thickness of the solder to the substrate. Alternatively, the former is slower than the latter, and the amount of molten solder is reduced to make the thickness of the solder to the substrate thinner, so that the thickness of the solder can be adjusted to be as thin as possible.

Furthermore, it is performed by setting the moving speed of the soldering iron tip part to 150 to 200 mm/s to form a uniform and thin solder layer.

Furthermore, it is carried out by setting the material of the soldering iron tip or the material of the coating soldering tip to a material with high hardness and wear resistance.

Furthermore, it is performed by setting the material to any one of titanium, titanium alloy, silicon, or silicon alloy.

Furthermore, it is done by setting the coating thickness of the soldering iron tip to 5 to 15 μm.

As mentioned above, the present invention increases the cross-sectional area and heat capacity of the soldering iron tip to reduce the heating temperature of the soldering iron tip, so as to reduce the thermal damage to the substrate, and the ultrasonic conduction is carried out well to reduce the ultrasonic output. Remove the attachments on the substrate, and form a thin and uniform solder layer, without damaging the substrate film, and form a uniform and thin solder layer. The present invention has the following features based on the content described in this. (1) By increasing the cross-sectional area of the soldering iron tip (approximately 4 times in the experiment), the heating temperature of the soldering iron tip can be reduced by about 90°C (experimental), and the molten solder melted by the soldering iron tip is attached and soldered When the substrate is close to (about 30μm), the thermal damage to the substrate can be reduced.

(2) In addition, in (1), the temperature of the substrate preparation heating stage that prepares to heat the substrate can be reduced by about 30°C, which can help reduce the thermal damage to the substrate.

(3) Furthermore, in (1), by increasing the cross-sectional area of the soldering iron tip (about 4 times in the experiment), the conduction of the ultrasonic waves from the ultrasonic oscillator can be made good, and even The output is reduced to 2W, and the attachments on the substrate can be sufficiently removed to form a thin and uniform solder layer.

(4) The thickness of the solder layer on the substrate can be half to one-third of the previous thickness (that is, about 50 to 100 μm), and the amount of soldering material used can be reduced to half to one third. Reduce costs.

(5) By using metals with high hardness and wear resistance (titanium, titanium alloy, silicon, silicon alloy, etc.) to make the tip of the soldering iron or the tip of the coated soldering iron, the tip of the soldering iron can be greatly extended Life.

1: Substrate (solar cell substrate, silicon substrate)

2: Substrate loading station (substrate preparation heating station)

3: Soldering iron tip

31: Soldering iron tip temperature (T3)

32: Soldering iron tip moving device (S1)

4: Soldering iron tip heating device

5: Ultrasonic oscillation device

51: Transmission path

6: Solder

7: Solder preparation heating device (T2)

8: Solder sliding device (S2)

11, 21: Substrate

12: TA mixed layer

13: TA coating

14, 24: the surface of the original substrate

22: SA mixed layer

23: SA coating

Fig. 1 is a configuration diagram of an embodiment of the present invention.

Figure 2 is a flowchart illustrating the operation of the present invention.

Fig. 3 is a flowchart (Part 2) for explaining the operation of the present invention.

Figure 4 is the temperature setting flow chart of the present invention.

Fig. 5 shows an example of a substrate to be soldered according to the present invention.

Fig. 6 shows an example of the configuration of the welding device of the present invention.

Figure 7 is an improved example of the soldering tip of the present invention.

Figure 8 is an example of the tip speed (S1) of the present invention.

Figure 9 is an example of the solder supply speed (S2) of the present invention.

Figure 10 is an example of temperature setting of the present invention.

Figure 11 is an example of ultrasonic power setting of the present invention.

Figure 12 shows an example of the present invention and the conventional setting.

Figure 13 is an example of a welding photograph of the present invention.

Figure 14 is an example of the shape of the soldering tip of the present invention.

Figure 15 is an explanatory diagram of the ABS coating process of the present invention.

Figure 16 is an explanatory diagram (hardness) of the ABS coating process of the present invention.

Figure 17 is an application example of the ABS coating butt soldering iron of the present invention.

Figure 18 is an example of surface microscope image (molybdenum) coated with ABS of the present invention.

Figure 19 is an example of a surface microscope image of the ABS coating of the present invention (Part 2).

Figure 20 is a flow chart for explaining the operation of the present invention (without preliminary welding).

Figure 21 is an example of ribbon connection of the present invention.

Figure 22 is an example of wire connection of the present invention.

Figure 23 shows an example of welding conditions of the present invention.

Figure 24 shows the welding conditions and successful welding examples of the wire material of the present invention.

Fig. 25 is an explanatory diagram of the presence or absence of preliminary soldering and the presence or absence of solder supply in the ultrasonic soldering of the present invention.

[Example 1]

Fig. 1 is a block diagram showing an embodiment of the present invention. The first figure is an example of ultrasonic welding on the back surface of the solar cell substrate (silicon substrate), and it can also be applied to the surface of the solar cell substrate.

In Figure 1, the substrate (solar cell substrate, silicon substrate) 1 constitutes the silicon substrate of the solar cell (refer to Figure 5).

The substrate loading table (substrate preparation heating table) 2 is one that mounts the substrate 1 and performs preliminary heating. Here, it is one that heats the solder to a predetermined temperature below the melting temperature and above room temperature.

The soldering iron tip 3 is a soldering iron tip that constitutes a soldering device. It is arranged close (usually about 30 μm) to the substrate 1 to be soldered, and is heated to a predetermined temperature by the soldering iron tip heating device 4, and supersonic waves are applied from the ultrasonic oscillation device 5. In the state of sonic waves, the tip moving device 32 moves in the welding direction.

The temperature of the soldering iron tip (T3) 31 is the temperature T3 of the soldering iron tip.

The soldering iron tip moving device (S1) 32 is a device that moves the soldering iron tip 3 in the welding direction.

The soldering iron tip heating device 4 heats the soldering iron tip 3 to a predetermined temperature, and is a heating body such as a ceramic heater.

The ultrasonic oscillating device 5 is a device that oscillates ultrasonic waves and supplies them to the soldering iron tip 3, where it generates an ultrasonic output of 2W to 6W.

The solder 6 is a wire-shaped solder supplied to the soldering iron tip 3, and is a solder that contains Sn, Zn, etc., and does not contain Pb, etc.

The solder preheating device (T2) 7 is a device that preliminarily heats the wire-shaped solder 7 and preliminarily heats the solder 7 to a temperature below which the solder 7 can melt.

The solder sliding device 8 automatically supplies the preheated wire-shaped solder 7 to the tip portion of the soldering iron tip 3 at a predetermined speed as shown in the figure.

Next, the operation of the structure of Fig. 1 will be described in detail using Figs. 2 and 3.

Figures 2 and 3 are flowcharts showing the operation of the present invention.

In Figure 2, the S1 system prepares a solar cell substrate (with an aluminum pattern formed on the back surface). This is to prepare a solar cell substrate (silicon substrate) as shown in Fig. 5 described later. The silicon substrate 1 in Fig. 5 is formed on the back surface of the aluminum paste by screen printing and sintering as shown in Fig. 5(b) to form an aluminum film 11, and the strip portion in the longitudinal direction (corresponding to The back portion of the bus bar electrode formed on the surface outside the figure) exposes the silicon substrate 1 without the base of the aluminum film 11.

S2 is to heat the substrate stacking table to a predetermined temperature T1. Here, the substrate mounting table 2 in FIG. 1 is heated to a predetermined temperature T1 (a temperature slightly lower than the temperature at which the solder 7 will melt).

In S3, the substrate is placed on the substrate stacking table. Thereby, the substrates are sequentially placed on the substrate stacking table 2 heated to the predetermined temperature T1, and sequentially heated to the predetermined temperature T1.

S4 system heats the solder preparation heating device and the soldering iron tip to predetermined temperatures T2 and T3 respectively. Here, the solder preparation heating device 6 in Figure 1 is heated to a predetermined temperature T2 (a temperature slightly lower than the temperature at which the solder 7 will melt), and the soldering iron tip 3 in Figure 1 is heated to T3 (by The temperature at which the solder 7 will melt when ultrasonic waves are applied).

The S5 system sets the ultrasonic output to a predetermined power W. Here, the ultrasonic output of the ultrasonic oscillator 5 in Fig. 1 is set to a predetermined power W (in the experiment, it is, for example, in the range of 2 to 6W, ideally 2W).

In Figure 3, S6 makes the soldering iron tip close to the substrate surface (approximately 30μm on the substrate), and makes the molten solder adhere to the silicon substrate (or aluminum surface). This is to make the soldering iron tip 3 of Fig. 1 approach the back surface of the substrate 1 (refer to Fig. 5(b)) at about 30μm, and the aluminum surface of the back surface of the substrate 1 or the exposed silicon substrate (silicon The surface) uses the supplied ultrasonic waves to remove the adherents on the surface, and then melts the solder, which is prepared by heating and melted by the wire-shaped solder 7 supplied to the soldering iron tip 3.

S7 is to make the soldering iron tip move from the starting point to the end point of the welding object at a predetermined speed S1.

The S8 system raises the tip of the soldering iron at the end. By means of S6 to S8, the aluminum surface or silicon surface of Fig. 5(b) on the approaching substrate can be automatically supplied with molten solder to the soldering iron tip from the starting point. The end is followed.

The S9 system judges whether it is over. The department ends at YES. At NO, the system moves to the next welding start location at S10, and repeats S6 and the latter. For example, in the case of a solar cell substrate (silicon substrate) ^{of 150 mm 2, the experiment was repeated for 5 cells.}

As described above, the soldering iron tip 3 is arranged close to the aluminum surface or the silicon surface of the preheated solar cell substrate, and the preheated wire solder 7 is automatically supplied at the front end of the soldering iron tip 3 to form the soldering iron tip 3 The solder is melted, and ultrasonic waves are supplied from the soldering iron tip 3 to the aluminum surface or silicon surface of the adjacent solar cell to remove the adherents, and then move from the starting point to the end point, and then the solder is melted. Thereby, the molten solder can be adjusted to the aluminum surface or silicon surface. The method of causing damage to the surface and silicon surface is thin, firm and beautifully attached to the aluminum or silicon surface of the solar cell substrate. Through these operations, the solder tape (wire) can be firmly and directly fixed to the aluminum or silicon surface of the solar cell (in this case, a solder tape prepared for soldering is used instead of the wire solder 7 in Figure 1) , Or it can be pre-soldered with wire-like solder 7 and then soldered with the ribbon (also without ultrasonic waves).

Hereinafter, it will be explained in detail in order.

Figure 4 shows the temperature setting flow chart of the present invention. This is a detailed description of the settings of the temperatures T1, T2, and T3 described in the first, second, and third diagrams.

‧Temperature T1: The temperature of the substrate stacking table in Figure 1

‧Temperature T2: The temperature of the solder preparation heating device in Figure 1

‧Temperature T3: The temperature of the soldering iron tip 3 in Figure 1

In Figure 4, S11 sets the optimal temperature range of T1, T2, and T3. This is the optimal temperature range obtained in the pre-experiment.

S12 is to determine whether T1 is within a predetermined temperature range. This is to determine whether the current temperature T1 is within the optimal temperature range of T1 set by S11. When it is YES, the system goes to S13. When it is NO, return to S11 and repeat the operation.

S13 is to determine whether T2 is within a predetermined temperature range. This is to determine whether the current temperature T2 is within the optimal temperature range of T2 set by S11. When it is YES, the system goes to S14. When it is NO, return to S11 and repeat the operation.

S1 is to determine whether T3 is within a predetermined temperature range. This is to determine whether the current temperature T3 is within the optimal temperature range of T3 set by S11. When it is YES, the system starts welding at S15. When it is NO, return to S11 and repeat the operation.

As described above, when it is determined that the temperature T1 of the substrate loading table 2 in Fig. 1, the temperature T2 of the solder preparation heating device 6 and the temperature T3 of the soldering iron tip 3 have been adjusted to the optimum temperature ranges obtained in advance. (Described later), start welding (implement S5 and later in Fig. 2 described earlier), and the attachments on the aluminum surface or silicon surface of the solar cell substrate can be removed by ultrasonic waves, and the preparation The molten solder heated and melted is connected from the soldering iron tip and soldered to the adjacent aluminum surface or silicon surface.

Fig. 5 shows an example of a substrate to be soldered according to the present invention.

Fig. 5(a) is a cross-sectional view showing the back surface of the solar cell substrate (silicon substrate), and Fig. 5(b) is a plan view showing the back surface of the solar cell.

In Fig. 5 (a) and (b), the back surface of the solar cell (silicon substrate) 1 is as shown in the figure, where aluminum paste is coated/sintered to form an aluminum film 11, and formed on the corresponding There is no aluminum film on the part of the strip-shaped bus bar electrode on the surface not shown, and the structure of the silicon surface is exposed.

In the present invention, molten solder is bonded and soldered to the part of the aluminum film 11 on the back of the solar cell or the part where the silicon surface is exposed.

Fig. 6 shows an example of the structure of the welding device of the present invention. This welding device is composed of an ultrasonic oscillation device 5, a transmission path 51, and a soldering iron tip 3.

In Fig. 6, the ultrasonic oscillation device 5 corresponds to the ultrasonic oscillation device 5 in Fig. 1, which oscillates and outputs ultrasonic waves, and is capable of adjusting the ultrasonic output to within the range of 2W to 6W.

The transmission path 51 efficiently transmits the ultrasonic output generated by the ultrasonic oscillation device 5 to the soldering iron tip 3.

The soldering iron tip 3 is the soldering iron tip 3 of Figure 1, which is used to melt the preheated solder heated to a predetermined temperature T3 to generate molten solder, and to transmit the ultrasonic waves generated by the ultrasonic oscillator 5 through the transmission path 51 and receive and transmit to the aluminum surface or silicon surface of the solar cell substrate that is disposed close to and remove the attachments on the aluminum surface or silicon surface, and then solder the molten solder. The soldering iron tip 3 is as shown in the figure. Relative to the width (vertical direction), the length (the horizontal direction, which is the direction in which the soldering iron tip 3 moves and soldering) is longer (usually about 2 to 6 times). The latter part will be explained using Fig. 7 and Fig. 14).

As described above, the ultrasonic oscillation device 5 is connected to the soldering iron tip 3 through the transmission path 51, whereby the soldering iron tip 3 can supply ultrasonic waves to the aluminum surface or silicon surface of the solar cell substrate arranged close to the surface to adhere to the surface. After removing the material, the molten solder of the soldering iron tip 3 is then firmly welded to the aluminum or silicon surface.

Figure 7 shows an improved example of the soldering tip of the present invention.

Figure 7(a) shows an example of the shape of a traditional soldering iron tip. As shown in the figure, a conventional soldering iron tip uses a 1mm×1mm square or circular soldering part 33 for soldering. The conventional welding part 33 has no directionality and can be welded in any direction, which is convenient.

However, the contact area of the welded portion 33 is small. In the example shown in Fig. 7(a), it is a 1mm x 1mm rectangle with a 1mm square. The aluminum or silicon surface that is in contact has a large thermal impedance and a large ultrasonic impedance.

Therefore, in the experimental example of Fig. 7(b) of the present invention, the width is also set to 1mm, and the length is set to 4 times of 4mm to increase the contact area by 4 times, thereby making the contacting aluminum surface Or the thermal impedance of the silicon surface is reduced to about 1/4, and the ultrasonic impedance is also reduced to about 1/4. As a result, the heating temperature of the soldering iron tip 3 can be reduced corresponding to the aforementioned reduction, and the ultrasonic output can be reduced . As a result, the thermal damage and ultrasonic damage of the aluminum surface or the silicon surface are reduced, and a thin solder layer (half to one-third the thickness of the conventional one) is formed, and the solder can be firmly and beautifully welded.

Figure 7(b) shows an example of the shape of the soldering tip of the present invention. As shown in the figure, the soldering iron tip of the present invention uses a rectangular welding part 34 with a width of 1 mm and a length of 4 mm for welding. The welding part 34 of the present invention in Fig. 7(b) is compared with the welding part 33 in Fig. 7(a), because the contact area to the aluminum surface or the silicon surface is 4 times, so the thermal resistance and ultrasonic wave can be reduced. The impedance is reduced to about 1/4, and the cross-sectional area of the soldering iron tip 3 is increased by 4 times and the heat capacity is increased (about 4 times).

Figure 7(c) shows another example of the shape of the soldering tip of the present invention. As shown in the figure, the other soldering iron tip of the present invention has a rectangular soldering portion 34 with a width of 1 mm or less and a length of about 4 mm. Regarding the other shape examples of the soldering iron tip, especially when the width is to be set to 1mm or less, the tip width of the soldering iron tip 3 in Figure 7(b) is set to be 1mm or less and the length to be 4mm or less. The smaller shape of the constructor is a convenient construction. In other words, in a state where the shape of the soldering iron tip is almost the same as or slightly larger than the thermal impedance, ultrasonic impedance, and thermal capacity of Fig. 7(b), only the width can be arbitrarily reduced to 1 mm or less.

As mentioned above, in the lengthwise direction relative to the width of the soldering iron tip (4 times in the experiment), the thermal resistance between the aluminum surface or the silicon surface of the solar cell substrate can be reduced under the condition that the same width can be soldered Decrease (in the experiment, the system is reduced to about 1/4) and heat increases the capacity (about 4 Times), the result is that the temperature of the soldering iron tip can be reduced and the ultrasonic output can be reduced, and the thermal damage and ultrasonic damage of the aluminum or silicon surface of the solar cell substrate can be reduced to realize the thin solder layer welding, and realize the strong and beautiful welding .

Figure 8 shows an example of the tip speed (S1) of the present invention. This is the following information related to the diagram corresponding to the speed S1 of the soldering tip 3 in Figure 1.

Here, the speed refers to the speed S1 at which the soldering iron tip 3 of FIG. 1 moves relative to the aluminum surface or the silicon surface of the solar cell substrate 1 to be soldered. The speed example (mm/s) is the speed example of the upper limit, the best range, and the lower limit of the shape of the soldering iron tip in Figure 7(b) used in this experiment. Remarks are the observed welding conditions at each speed (upper limit, optimal range, lower limit). This will be explained below.

(1) When the speed of the soldering iron tip 3 in Figure 1 is set to the upper limit of 200mm/s or more, the molten solder melted in the soldering iron tip 3 is slow to supply the aluminum surface or silicon surface of the solar cell substrate 1, resulting in The solder on this surface is interrupted, so the upper limit of the speed is set to 200mm/s.

(2) When the optimum speed range is 150 to 200 mm/s, the aluminum surface or silicon surface of the solar cell substrate 1 can be uniformly and thinly coated with solder.

(3) When the speed is lower than 150mm/s, the supply of solder becomes excessive, so that the solder may accumulate on the aluminum surface or the silicon surface.

From the above experimental results, it can be seen that the best range of the speed of the soldering iron tip 3 in Figure 1 is 150 to 200mm/s. Therefore, no matter it is too slow or too fast, it cannot be even on the aluminum or silicon surface. Coat solder evenly and thinly. In addition, the shape of the soldering tip 3 shown in Figure 7(b) was used in the experiment. However, if the shape (width, etc.) is different, or the thickness of the solder is different, it must be distinguished by experiment. Find the best speed.

Figure 9 shows an example of the solder supply speed (S2) of the present invention. This is the following information related to the drawing corresponding to the speed S2 at which the solder 7 is supplied to the soldering tip 3 in the first figure.

Here, the speed is the speed S2 at which the solder 6 is supplied to the soldering iron tip 3 by the solder slide device 8, and the solder 6 is preheated by the solder preparation heating device 7 in FIG. 1. Remarks are the welding status observed at this speed [fast (faster than the soldering iron tip speed), optimal range, slow (slower than the soldering iron tip speed)]. This will be explained below.

(1) When the speed of the solder 7 supplied by the solder sliding device 8 of Fig. 1 is increased (faster than the speed of the soldering iron tip), the solder 7 is supplied to the soldering iron tip 3 at a speed faster than the speed of the soldering iron tip 3 In other words, the supply of solder will become excessive, and the molten solder will be thickly applied to the aluminum or silicon surface of the solar cell substrate 1, and the solder will accumulate at a faster rate.

(2) When the speed of the solder 6 is in the optimum range (when the speed of the solder 6 is the same as the speed of the soldering iron tip), the solder can be evenly and thinly coated on the aluminum surface or the silicon surface of the solar cell substrate 1.

(3) When the speed of the solder 7 is slow (slower than the speed of the soldering iron tip), the solder 7 is supplied to the soldering iron tip 3 at a speed slower than the speed of the soldering iron tip 3, that is, it will become the supply of solder. If it is less, the molten solder will be thinly coated on the aluminum surface or the silicon surface of the solar cell substrate 1, and the solder will be interrupted when it is slower.

From the above experimental results, it can be seen that when the optimal range of the supply speed of the solder 7 using the solder slide device 8 in Figure 1 is the same as the speed of the soldering iron tip, the solder can be applied uniformly and thinly; when the supply speed is set slightly When the speed is faster than the soldering iron tip, the solder can be thickened, but when it is too fast, the solder will accumulate; when the feeding speed is set to be slightly slower than the soldering iron tip, the solder can be thinned, but the solder will be interrupted when it is too slow . In addition, it is also possible to adjust (increase or decrease) the thickness of the solder by changing (increasing or decreasing) the cross-sectional area of the supplied wire solder 7.

Figure 10 shows an example of temperature setting of the present invention. This corresponds to the substrate stacking table 2, the solder preparation heating device 7, and the soldering iron tip heating device 4 of Fig. 1 and is related to the following information.

Here, the devices are the substrate stacking table 2, the solder preliminary heating device 7, and the soldering iron tip heating device 4 shown in FIG. 1. The set temperature is an example of the set temperature set by each device in the experiment, and the set temperature range is the appropriate set temperature range used by each device in the experiment. This will be explained below.

(1) The substrate stacking table (T1) 2 in Figure 1 is a slightly lower temperature than the temperature at which the solder 6 melts when ultrasonic waves are applied and becomes molten solder at the soldering iron tip 3. In the experiment, it was set to 170 ℃, appropriately set the temperature range from 140 to 200℃.

(2) The solder preparation heating device (T2) 7 in Figure 1 is set to preheat the solder 6 to a temperature slightly lower than the "temperature at which the solder becomes molten solder at the soldering iron tip 3", which is set in the experiment It is 160°C, and the temperature range is appropriately set in the range of 150 to 200°C.

(3) The soldering iron tip heating device (T3) 4 in Figure 1 is set to the temperature at which the solder 6 will melt when ultrasonic waves are applied and become molten solder at the soldering iron tip 3. In the experiment, it was set to 360°C, and set appropriately The temperature range is from 340 to 450°C.

In addition, the above set temperature and set temperature range depend on the material of the solder 6 used, and the above experimental example uses Sn/Zn solder. Since other welding materials have different melting temperatures, experiments must be used to obtain and set the set temperature and set temperature range.

Figure 11 shows an example of ultrasonic power setting of the present invention. This corresponds to the oscillation output power of the ultrasonic oscillator 5 in Fig. 1 and is related to the following information.

Here, the power is the ultrasonic oscillation output (power) supplied to the soldering iron tip 3 by the ultrasonic oscillation device 5 in FIG. 1. W is the power (W) set in the experiment. Remarks are information on the observed conditions of each power. This will be explained below.

(1) When the ultrasonic oscillation power of the ultrasonic oscillation device 5 in Fig. 1 is set to be large (6W or more in the experiment), the following phenomena are confirmed.

‧May reduce the temperature of the soldering iron tip

‧Damage or breakage of substrate or crystal

‧The solder bonding surface cannot be smooth

Here, "it is possible to lower the temperature of the soldering iron tip" means that when the ultrasonic output (power) is set to be large (for example, 6W or more), the heating temperature of the soldering iron tip 3 when forming molten solder will decrease due to the increase of the ultrasonic output. As a result, the temperature of the soldering iron tip (T3) may be reduced. Furthermore, "substrate or crystal damage, breakage" means that the ultrasonic output is set to be large, so the result is that the large ultrasonic output causes ultrasonic damage to the aluminum surface and silicon surface of the solar cell substrate, resulting in The possibility of damage to the substrate or crystals and even film breakage increases. Furthermore, "the solder bonding surface cannot be smoothed" means that due to the large ultrasonic output, the solder on the aluminum surface and the silicon surface cannot be smoothed, and it is in a rough state.

(2) When the ultrasonic output is in the optimal range (for example, in the range of 2W to 6W, preferably 2W), the solder can be uniformly and thinly coated on the aluminum surface and the silicon surface of the solar cell substrate 1.

(3) When the ultrasonic output is small (for example, 2W or less), the following phenomena are confirmed.

‧The temperature of the soldering iron tip must be increased

‧Inability to sufficiently remove oxides, etc.

Here, "it is necessary to raise the temperature of the soldering iron tip" means that when the ultrasonic output (power) is set to be small (for example, 2W or less), the heating temperature of the soldering iron tip 3 when forming molten solder will be caused by setting the ultrasonic output to a small value. As a result, it will be necessary to increase the temperature (T3) of the soldering iron tip. Furthermore, "the oxides etc. cannot be sufficiently removed" means that since the ultrasonic output is set to be small, as a result, the deposits, oxides, etc. on the aluminum surface and silicon surface of the solar cell substrate cannot be sufficiently removed.

Figure 12 shows a setting example of the present invention and the conventional one. This figure 12 compares the conventional one with the present invention for each item, and specifically describes the difference as shown in the following figure. Here, the items are items for comparison, and as shown in the figure are "tip temperature (T3)" and so on. The traditional is a specific example of the tradition of the display item, and the present invention is a specific example of the invention of the display item. Remarks are detailed descriptions of the project.

Here, the temperature (T3) of the soldering iron tip is traditionally 450°C. However, in the present invention, when the width of the shape of the front end of the soldering iron tip 3 is set to be the same, the length is set to approximately 4 times the cross-sectional area As a result (refer to Fig. 7(b)), the tip temperature (tip heating temperature) was 360°C, and it was confirmed by experiments that the tip temperature (T3) was reduced by about 90°C. Thereby, the temperature of the molten solder of the soldering iron tip 3 when it approaches and adheres to the aluminum surface and the silicon surface of the solar cell substrate 1 is lowered, and thermal damage can be reduced.

The substrate pre-heating temperature (T1) can reduce the temperature of the soldering iron tip, and even if the substrate pre-heating temperature is reduced from 200°C by about 30°C to 170°C, the soldering iron tip 3 of the present invention can be used [Compared with the past Compared with the soldering iron tip (refer to Fig. 7(b)), which is about 4 times the length, soldering is performed.

Regarding the tip speed (S1), by setting the tip of the present invention, the speed can be increased by only 28mm/s from the previous 150mm/s to 178mm/s.

As far as the solder supply is concerned, 200 pulses are used in the present invention.

The height of the soldering iron tip is 20 to 30 μm in the past, but is controlled to 30 μm in the present invention.

Although there is no solder preheating temperature (T2) in the past, in the present invention, it is preheated to 160°C.

The ultrasonic oscillation output is 6W in the past, but in the present invention, the soldering iron tip of the present invention is used [refer to Fig. 7(b)], the width is set to be the same and the cross-sectional area is set to 4 times to reduce the ultrasonic impedance. Even 2W can sufficiently remove the adherents on the solar cell substrate 1 and bond the molten solder, and can be welded uniformly and thinly (one-half thickness in the past).

The weight of the solder is 0.02 to 0.03 g per bus bar in the past, and 0.1 to 0.15 g of the solder is used for 5 bars (5 bus bars) per wafer. In the present invention, each bus bar is 0.01g, and 5 bars (5 bus bars) are used on a wafer with 0.05g of solder, so it can be reduced to half to one third of the traditional one, and the use of solder is reduced. the amount. Furthermore, the reduction in the amount of solder used in the present invention can reduce the thickness of the solder on the aluminum surface and the silicon surface of the solar cell substrate 1 to be half to one third of the conventional one.

Figure 13 shows an example of a welding photograph of the present invention. The horizontal direction (a) in Fig. 13 shows an example of a welding photograph under suitable conditions (in the case of the present invention in Fig. 12), and a beautiful, thin and uniform welding appearance can be observed.

On the other hand, the vertical direction in Figure 13 (b) is an example of a photo showing poor welding under unsuitable conditions. In this example of poor welding, the surface of the welded part is uneven, and unevenness can be observed. The appearance of poor welding of ground welding.

Figure 14 shows an example of the shape of the soldering tip of the present invention.

Figure 14(a) shows an example of the width of the soldering iron tip. This figure illustrates the welding state when the width of the soldering iron tip 3 to be soldered is the same, larger, and smaller than the width of the pattern of the welding object (here, the bus pattern is taken as an example), as shown in the figure Generally distinguish the width of the soldering iron tip (larger, same, smaller), and record the welding state as shown in the following figure.

(E.g. 1mm) For example, the solder is snaking

As mentioned above, it can be seen that the best results can be obtained when the width of the soldering iron tip (the width at right angles to the welding direction) is the same as the width of the pattern of the welding object. When the width of the soldering iron tip is too wide or too narrow compared to the width of the pattern, good results cannot be obtained.

Figure 14(b) shows an experimental example. This figure shows the conditions and results of the experiment. The following is the content of the figure.

‧The width of the soldering iron tip matches the width of the bus bar pattern on the surface. This is as shown in the example of the shape of the soldering iron tip of the present invention shown in Fig. 7(b). The width of the soldering iron tip of the present invention is matched to 1 mm of the width of the bus bar pattern of the welding object.

‧The length of the soldering iron tip depends on the unevenness (undulation) of the processed shape of the wafer surface. This means that the length of the soldering iron tip must match the length of the soldering iron tip under the condition that the molten solder at the tip of the soldering iron tip is attached to the part to be soldered (the pattern on the wafer, such as the busbar pattern, etc.) The cycle (for example, 1 cycle) of the undulation (concavity and convexity) of the processed shape of the round surface depends on the undulation (concavity and convexity) of the wafer.

‧In this experimental example, since the unevenness (undulation) of the current wafer processing shape falls into 4mm, the length of the soldering iron tip is set to 4mm. This is because 1 period of the unevenness (undulation) of the wafer processing shape used in the experiment falls within 4mm, so the length of the soldering tip shape example of the present invention shown in Figure 7(b) is matched It becomes 4mm.

As mentioned above, the width and length of the soldering iron tip are determined (adjusted) according to the width of the part to be soldered (width of the pattern) and the unevenness (undulation) of the surface of the wafer to be soldered, and to reduce Small thermal impedance and ultrasonic impedance, and increase the heat capacity to determine (adjust) the shape of the soldering iron tip. The result is as described. According to the present invention, a uniform solder layer with a thickness of one-half to one-third of the traditional thickness can be strongly welded on the aluminum and silicon surfaces of the solar cell substrate, and the heating temperature of the soldering iron tip and Reduce the ultrasonic output, and reduce the thermal damage and ultrasonic damage of the soldering surface of the solar cell substrate.

Figure 15 shows an explanatory diagram of the ABS coating process of the present invention.

Figure 15(a) schematically shows the appearance of titanium (TA) treatment.

In Fig. 15(a), the base material 11 is the base material (material) of the soldering iron tip of the ultrasonic soldering iron, for example, titanium metal (titanium alloy). The base material 11 is not limited to titanium metal, and any metal may be used as long as it is a metal with good thermal conductivity, hardness, and wear resistance (described later in FIG. 17, etc.). In addition, in order to form a film with high hardness and wear resistance on the substrate 11 by ion sputtering, it must be one with high adhesion or high alloying properties.

The TA mixed layer 12 is formed on the surface to the inside of the substrate 11 by impacting ions (titanium ions) by ion sputtering from above the substrate 11 as shown in the figure. The thickness of the TA mixed layer 12 is usually as shown in the figure, and is about 5 to 10 μm.

The TA coating film 13 is formed on the substrate 11 when the ions collide with ions (titanium ions here) by ion sputtering from above the substrate 11, and a titanium coating film (TA coating film) as shown in the figure is formed on the substrate 11 . The thickness of the TA coating film 13 is generally as shown in the figure, and is appropriately about 5 to 10 μm. If necessary, it can also be slightly polished from above to make it thin but flatten and improve flatness. Here, the ion sputtering (ABS coating) in the experiment was implemented with a pulse voltage of 50 Hz, a maximum of 220 V, and a current of 42 A (normal mode) to obtain unevenness of 10 μm or more. The area of 10×10mm ² was treated for 13 minutes.

The original substrate surface 14 is the surface of the substrate 11 before ion sputtering.

As described above, when titanium (or titanium alloy) ion sputtering is performed from above the substrate 11, the TA mixed layer 12 is formed from the surface of the substrate 11 to the inside, and is firmly fixed, and at the same time, the TA mixed layer 12 A TA coating film 13 is formed on the upper part of the, and a soldering iron tip with the high hardness and wear resistance of the TA coating film 13 can be made. The surface of the TA coating film 13 may be slightly polished as needed to make it flattened and have good smoothness.

Figure 15(b) schematically shows the appearance of the silicon (SA) process.

In Fig. 15(b), the base material 21 is the base material (material) of the soldering iron tip of the ultrasonic soldering iron, for example, silicon metal (silicon alloy). The base material 21 is not limited to silicon metal. If it is a metal with good thermal conductivity, hardness, and wear resistance, it can be any metal (described later in FIG. 17, etc.). In addition, in order to form a film with high hardness and wear resistance on the substrate 21 by ion sputtering, it must be one with high adhesion or high alloying properties.

The SA mixed layer 22 is formed on the substrate 21 from the surface to the inside of the substrate 21 by ion sputtering to cause ions (herein, silicon ions) to collide, as shown in the figure. The thickness of the SA mixed layer 22 is usually about 5 to 10 μm as shown in the figure.

The SA coating film 23 is a silicon coating film (SA coating film) as shown in the figure when ions (herein, silicon ions) collide from the substrate 21 by ion sputtering. The thickness of the SA coating film 23 is usually about 5 to 10 μm as shown in the figure. It can also be slightly polished from above as needed to make it thinner and flattened with good planarity.

The original substrate surface 24 is the surface of the substrate 21 before ion sputtering.

As described above, if silicon (or silicon alloy) ion sputtering is performed on the substrate 21, the SA mixed layer 22 will be formed and firmly fixed from the surface to the inside of the substrate 21, and at the same time on the substrate 21 The SA coating film 23 is formed, and a soldering iron tip having the high hardness and abrasion resistance of the SA coating film 23 can be manufactured. The surface of the SA coating film 23 may be slightly polished as needed to make it flattened and have good smoothness.

Figure 16 shows an explanatory diagram (hardness) of the ABS coating process of the present invention. This figure 16 shows an example of the coating film hardness (HV: Vickers hardness) of the TA treatment of the above figure 15(a).

In Figure 16, the column on the left is in the three states of Figure 15(a): TA treatment, polishing to the original substrate surface 14, and polishing to 5μm from the original substrate surface. In this case, the coating film hardness (HV) on the right is an example. Here, the base material 11 is an example of an Fe-based base material, and has a hardness of the following graph.

Here, the hardness of the coating film on the TA surface is 2500HV, which means that the state after the TA treatment in Figure 15(a) is maintained (maintained after the 5-15μm thick TA coating film 3 is sputtered with titanium ion State), the hardness of the coating film is about 2500HV. This means that compared to the hardness of the conventional ultrasonic soldering iron whose tip is stainless steel (SUS304), the hardness is 150HV (refer to Figure 17 described later), and the hardness of the latter after the TA treatment is harder and up to about 16 times (resistant) Abrasion is also roughly the same).

Similarly, the grinding process to 2000HV of the original substrate surface means that the hardness of the coating film when the surface 14 of the original substrate is polished from the state after the TA treatment in Figure 15(a) is about 2000HV. This means that the hardness of the stainless steel (SUS304) is 150HV (refer to Figure 17 below) compared to the traditional ultrasonic soldering iron with a hardness of 150HV (refer to Figure 17 below). The hardness of the latter after the TA treatment is harder and up to about 13 times (wear-resistant) Consumption is also roughly the same).

Similarly, the grinding process to 1000HV 5μm away from the original substrate surface means that the coating film hardness is about 1000HV when it is polished from the state after TA treatment in Figure 15(a) to 5μm away from the original substrate surface. This means that the hardness of the stainless steel (SUS304) is 150HV (refer to Figure 17 below) compared to the traditional ultrasonic soldering iron with the tip of stainless steel. The hardness of the latter after the TA treatment is harder and up to about 6 times (wear-resistant) Consumption is also roughly the same).

Figure 17 shows an application example of the ABS of the present invention applied to a soldering iron. Figure 17 shows the hardness (HV), specific heat (J/KgK), and thermal conductivity (W/mK) of the TA coating film in Figure 15 (a) and the SA coating film in Figure 15 (b). ).

In Figure 17, when the column on the left shows the TA coating film in Figure 15 (a), the SA coating film in Figure 15 (b), and other materials, it is the hardness, specific heat, and heat conduction on the right. Examples of the value of the rate have the following hardness, specific heat, and thermal conductivity in the diagram.

Here, the coating film/material of the soldering tip in the left column uses molybdenum, chromium-molybdenum steel, SUS304, etc. in the past, and the hardness is in the range of 147 to 415HV (hundreds of HV) (refer to the description on the right side of Figure 17 "(1) Original hardness (hundreds of HV)").

When the TA coating film of Figure 15(a) of the present invention is formed on the surface of the conventional soldering iron tip (molybdenum, chromium-molybdenum steel, SUS304), it is known that the hardness of the TA coating film is about 6 times 2500HV, that is, the hardness will be It becomes higher (refer to the "(2) Hardness after treatment (2500HV)" in the diagram of Fig. 17), and it is known that the abrasion resistance becomes higher in the same way.

Similarly, as shown on the right side of Figure 17, it is known to increase from "(3) original thermal conductivity (16.3 of SUS304)" to "(4) thermal conductivity after change (147 of molybdenum)".

In other words, changing the base material of the soldering iron tip from the traditional "SUS304" to the "molybdenum" of the present invention can increase the thermal conductivity by about 9 times, and form a TA coating on the surface, which only increases the hardness of the surface. 6 times.

Here, by changing the base material of the soldering iron tip from SUS304 to molybdenum, the characteristics of heat to the silicon substrate can be greatly improved, especially the thermal conductivity, and the exchange frequency of the soldering iron tip can be extended to about 6 months. about. However, due to the low hardness, the replacement frequency of the soldering iron tip is about 6 months. Furthermore, the TA treatment (TA coating) of molybdenum which is the base material of the soldering iron tip (refer to Figure 15(a)) can increase the hardness and increase the frequency of soldering tip replacement to about one and a half years.

Figure 18 shows an example of a surface microscope image (molybdenum) coated with ABS of the present invention. The ABS coating shown in Fig. 18 was carried out in an experiment with a pulse voltage of 50 Hz, a maximum of 220 V, and a current of 14 A (mild mold) to obtain an unevenness of about 5 μm. Treat a 10×10mm ² area for 40 minutes.

Figure 18 (a) shows the microscope image of the molybdenum surface (substrate), and Figure 18 (b) shows the microscope image of the TA surface (coated with titanium). The images of the two are the images with increasing magnification in the order of 5, 10, 20, and 50 times from top to bottom.

On the molybdenum surface (substrate) in Figure 18(a), as shown in the figure, it can be observed after machining in the horizontal direction.

The TA surface (coated with titanium) in Figure 18(b) shows the island-like appearance of titanium formed by titanium ion sputtering on the molybdenum surface of the soldering iron tip substrate. The TA surface is shown schematically in Fig. 15(a) mentioned above, and there are island-shaped asperities on the surface. Therefore, as needed, the TA surface can be created as described in Fig. 15(a). ", "Grinding to the original substrate surface", "Grinding to 5μm from the original substrate surface" to flatten the surface. In addition, the more polished, the more the hardness decreases from 2500 to about 1000 HV as described in Fig. 16. Therefore, it is necessary to perform polishing that can obtain the most suitable flatness depending on the application.

The SA surface (silicon coating) in Figure 18(c) is on the molybdenum surface of the soldering iron tip substrate. It is observed that the silicon is sputtered to form islands. The SA surface has island-shaped asperities as shown schematically in the 15th (b) mentioned above. Therefore, it can be created as described using the 15th (b) as required. "TA surface", "grind processing to the original substrate surface", "grind processing to 5μm from the original substrate surface" to flatten the surface. In addition, the more polished, the smaller the hardness like the TA coating film. Therefore, it is necessary to perform polishing that can obtain the most suitable flatness depending on the application.

Figure 19 shows an example of a surface microscope image of the ABS coating of the present invention (Part 2). This figure is 4 times of Mo (molybdenum) in Figure 18 (a), TA (titanium coating) in Figure 18 (b), and SA (silicon coating) in Figure 18 (c). An example of an image of a stereo microscope.

Next, the process of directly ultrasonically soldering the solder tape or wire (wire) belonging to the take-out line to which the solder is attached to the substrate or the film formed on the substrate will be described in detail using FIGS. 20 to 25.

Figure 20 shows a flow chart illustrating the operation of the present invention (without preliminary welding).

In Figure 20, S101 sets the temperature of the soldering iron, the wafer mounting table, etc., and the ultrasonic oscillation frequency. This S101 is to perform the following preliminary preparations before ultrasonic welding.

‧Soldering iron: Heat to a predetermined temperature (heat to the temperature at which the solder attached to the soldering tape or wire will melt).

‧Wafer mounting table: The wafer mounting table for the substrate will be preheated to a predetermined temperature (a temperature slightly lower than the melting temperature of the solder attached to the ribbon or wire, such as 180°C (described later)).

‧Ultrasonic oscillation frequency, etc.: Ultrasonic waves with a predetermined frequency and a predetermined output are adjusted in such a way that they are supplied from the soldering iron tip to the wafer belonging to the substrate (for example, as described later, the ultrasonic wave is adjusted to tens of KHz, 1 to 6W). The way the sound waves are supplied to the soldering iron tip can be adjusted).

S102 is to install the wafer in a predetermined position. This S102 is the process of ultrasonic welding of the ribbon or wire, for example, the solar cell wafer is transported by an unillustrated automated machine and fixed to a predetermined position of a wafer mounting table heated to a predetermined temperature by S101. The system is preheated to a predetermined temperature (for example, 180°C) in an instant when it is fixed.

S103 is to send out the wire or solder tape with solder attached. This S103 is to use an unillustrated automated machine to send the wire (wire) or ribbon previously attached with solder to the predetermined position of the wafer. The predetermined position of the wafer is fixed to the predetermined position of the wafer mounting table in S102 Position and the predetermined position of the pre-heated wafer (the predetermined position of the substrate for ultrasonic welding or the film on the substrate). The wire material (wire) or soldering tape is sent out from the reel, or sent out from a carrying box containing a number of wires or soldering tape that have been cut to a predetermined length. In addition, especially when feeding the strands from the reel, occasionally The wire may be broken due to twisting, so it is ideal to use an automated machine to send out the wire material (wire material) that has been cut to a predetermined length from the placing box. But this is not the case when it is a ribbon.

S104 series are ultrasonic welding. In this S104, the wafer is fixed on the wafer mounting table in S102 and is ready to be heated to a predetermined temperature (for example, 180°C), and in S103, the wire (wire) or solder tape with solder attached is supplied (or cut). (Cut and placed) on the wafer or on the film (aluminum film, nitride film, glass film, etc.) that has been formed on the wafer, gently press the tip of the ultrasonic soldering iron to supply super Sound waves and remove garbage, etc., and melt the solder attached to the wire material (wire) or ribbon, and the wire or ribbon is connected to the wafer (substrate) or the film formed on the wafer (film on the substrate) Perform ultrasonic welding.

S105 is to judge whether there is a wafer to be processed. When it is YES, since there are still wafers to be processed, the processing of the next wafer (processing of S102 to S104) is repeated in S106. When NO, it ends because the processing of all wafers has been completed.

Through the above process, the pre-heated wafer (substrate) or the film formed on the wafer (the film on the substrate) can be used to make the wire (wire) attached with solder beforehand or the solder attached to the ribbon Melt, and the wire or ribbon is directly ultrasonically welded to the wafer or the film on the wafer. Thereby, compared with the above-mentioned wire material or ribbon without solder attached to the substrate or the film on the substrate, the following advantages are obtained.

1. In this example, since the solder is attached to the wire or the solder ribbon, there is no need for an automatic solder supply device, a preliminary heating device, etc.

2. Compared with the case where the solder is preliminarily soldered to the substrate or the film on the substrate, and then the wire or ribbon is soldered, this preliminary soldering step is not required.

Figure 21 shows an example of the solder ribbon connection of the present invention. The example shown in this figure is based on the flow chart in Fig. 20, direct ultrasonic welding of the solder tape with solder to the wafer (example Such as solar cells) or the film on the wafer, and the solder tape is firmly connected in terms of electrical and mechanical properties.

Figure 21(a) shows an example of connection to the finger surface, Figure 21(b) shows an example of connection to the silicon surface, and Figure 21(c) shows an example of connection to the back aluminum surface.

Figure 21(a) shows an example of the connection to the finger surface. Fig. 21 (a-1) shows an example of ultrasonic welding of a welding ribbon on the finger surface, and Fig. 21 (a-2) shows a view from the horizontal direction.

In the example shown in Fig. 21(a), the solder tape shown in the figure (the solder tape with solder attached) is directly ultrasonically welded to the finger surface formed on the silicon substrate according to the flowchart in Fig. 20, and the The ribbon is electrically connected to the finger surface (finger electrode), and the ribbon is mechanically and firmly connected (fixed) to the film (nitride film or glass film formed on the nitride film).

Figure 21(b) shows an example of connection to the silicon surface (substrate). Figure 21 (b-1) shows an example of ultrasonic welding with a solder ribbon on the silicon surface, and Figure 21 (b-2) shows a view from the horizontal direction.

In Fig. 21(b), the solder tape shown in the figure (the solder tape with solder attached) is directly ultrasonically soldered to the silicon substrate according to the flowchart in Fig. 20, and the solder strip is electrically connected to the silicon surface (Substrate), and an example in which the ribbon is mechanically and firmly connected (fixed) to the silicon surface (substrate).

Figure 21(c) shows an example of connection to the aluminum surface on the back side. Fig. 21 (c-1) shows an example of ultrasonic welding of a solder ribbon on the aluminum surface on the back side, and Fig. 21 (c-2) shows a view from the horizontal direction.

In Fig. 21(c), the solder tape shown in the figure (the solder tape with solder attached) is directly ultrasonically welded to the aluminum surface on the back of the silicon substrate according to the flowchart in Fig. 20, and the solder tape is electrically connected An example of mechanically and firmly connecting (fixing) the ribbon on the back aluminum surface.

Figure 22 shows an example of the wire connection of the present invention. This figure shows the direct ultrasonic soldering of the wire material (wire) with solder attached to the wafer (e.g. Solar cell) or film on the wafer, and the wire material is firmly connected in terms of electrical and mechanical properties.

Figure 22(a) shows an example of connection to the finger surface, Figure 22(b) shows an example of connection to the silicon surface, and Figure 22(c) shows an example of connection to the back aluminum surface.

Figure 22(a) shows an example of the connection to the finger surface. Figure 22 (a-1) shows an example of ultrasonic welding of a wire material on a finger surface, and Figure 22 (a-2) shows a view from the horizontal direction.

In Fig. 22(a), the wire material shown in the figure (the wire material with solder attached) is directly ultrasonically soldered to the finger surface formed on the silicon substrate according to the flowchart in Fig. 20, and the An example of the wire material being electrically connected to the finger surface (finger electrode), and the wire material being mechanically and firmly connected (fixed) to the film (nitride film or glass film formed on the nitride film).

Figure 21(b) shows an example of connection to the silicon surface (substrate). Figure 21 (b-1) shows an example of ultrasonic welding of wire materials on a silicon surface, and Figure 21 (b-2) shows a view from the horizontal direction.

In Figure 21(b), it is shown that the wire material (the wire material with solder attached) is directly ultrasonically soldered to the silicon substrate according to the flowchart in Figure 20, and the wire material is electrically connected to the silicon substrate. An example of the surface (substrate), and the wire material is mechanically and firmly connected (fixed) to the silicon surface (substrate).

Figure 22(c) shows an example of connection to the back aluminum surface. Figure 22 (c-1) shows an example of ultrasonic welding of wire material on the aluminum surface on the back side, and Figure 21 (c-2) shows a view from the horizontal direction.

In Figure 21(c), the wire material (the wire material with solder attached) is directly ultrasonically soldered to the aluminum surface on the back of the silicon substrate according to the flow chart in Figure 20, showing that the wire material is electrically connected An example of mechanically and firmly connecting (fixing) the aluminum surface on the back side and the wire material.

Figure 23 shows an example of welding conditions of the present invention. This figure is an example of the welding conditions used in ultrasonic welding shown in the above-mentioned Figures 20, 21, and 22. As shown As shown, the sample, ultrasonic output, ultrasonic frequency, soldering iron temperature, and platform temperature (wafer holding stage temperature) are as shown in the following diagram.

Figure 24 shows the welding conditions and successful welding examples of the wire material of the present invention.

Figure 24(a) shows an example of successful roots/total roots. Among them, the number of successful examples shows that the cross-sectional shape of the wire is as shown in the figure, and the number of successful examples when the experiment is carried out with 0.5mm φ, 0.4mm φ, 0.3mm φ, and 0.2mm φ, is obtained as a diagram The following results.

Here, (a-1) "coating a solder with a thickness of about 10 μm" refers to a wire (copper wire) with about 10 μm of solder (attached by applying solder) attached to the wire (copper wire). (a-2) The "crushed shape of the above-mentioned wire" is a slightly pulverized ○-shaped wire of "a solder with a coating thickness of about 10 μm" as explained in Fig. 24(b) described later. (a-3) "Preliminary soldering, copper wire ○ shape" is prepared by pre-welding on a substrate and ultrasonically soldering a copper wire ○ shape wire to it.

As mentioned above, the cross-sectional diameter of the wire material is 0.5mm φ, 0.4mm φ, 0.3mm φ, 0.2mm φ, and ultrasonic welding is performed on the substrate (wafer) according to the flowchart in Figure 20. As a result of the experiment, the results described above can be obtained as follows.

(1) The original ○-shaped wire in (a-1) is difficult to ultrasonic welding, but other than that, ultrasonic welding can be performed (good electrical and mechanical connection).

(2) The wire of 0.5mm φ (the wire with solder attached to the surface of the copper wire of 0.5mm φ) is too hard, causing the wafer to crack and peel during ultrasonic welding on the wafer , And difficult to operate. When using this kind of strand, it must be softened by annealing or the like.

(3) As shown in (a-3), it can be seen that if preliminary welding (preliminary ultrasonic welding) is performed on the substrate in advance, even a copper wire ○-shaped wire material can be ultrasonically welded to the substrate.

Figure 24(b) is an explanatory diagram showing the crushed strands. This figure is an explanatory diagram showing "(a-2) the crushing shape of the above-mentioned strand" in the above-mentioned figure 24(a).

Figure 24 (b-1) shows an example of a wire material in the shape of a copper wire ○, and Figure 24 (b-2) shows an example of a crushed shape.

In Fig. 24 (b-2), it can be seen from experiments that the copper wire ○-shaped wire material in Fig. 24 (b-1) is slightly crushed up and down in the diameter direction as shown in the figure. When the contact portion of the lower substrate is about 100 to 200 μm or more, stable soldering can be achieved (Ultrasonic soldering can be performed according to the flowchart in Fig. 20).

Figure 25 is an explanatory diagram showing the ultrasonic welding of the present invention (with or without pre-welding, with or without solder supply, etc.). Among them, the vertical axis represents the difference between with and without preparation welding. The difference is that the part of the substrate (for example, the wafer or the film formed on the surface of the wafer) where the wire or ribbon is to be ultrasonically soldered, if the pre-soldering has been carried out in advance, it is yes, if it is not done For the case of pre-welding, it is none.

Furthermore, the horizontal axis represents the difference between welding with no material or ribbon. The difference is: if the wire or the surface of the ribbon is soldered (or solder coated) beforehand, it means yes, and if it is not soldered, it means no.

In Figure 25, for the combination of pre-welding, wire or soldering with non-adhesive solder, when ultrasonic welding is performed according to the flowchart in Figure 20, the diagram is shown The following experimental results.

Here, if it is explained in detail, the combination of (1), (2), (3), and (4) will obtain the following results.

(1) When it is "prepared soldering", "wire or soldering with attached solder", the following results will be obtained:

1. Stable operation,

2. Even the ○-shaped wire can be welded.

The result is that the part of the substrate (wafer) or the film formed on the substrate where the wire or ribbon is to be ultrasonically soldered, which has been pre-soldered by ultrasonic welding, will be attached to the wire Or the experimental results of the case of ultrasonic welding of the welding strip. Can work stably, and Even the ○-shaped wire material can be welded well (electrically connected and mechanically firmly connected).

(2) When it is "no preparation welding", "wire or solder with attached solder", the following results will be obtained:

1. After being crushed, the ○-shaped wire or ribbon is tightly connected,

2. ○The tight bonding of the shape wire is unstable,

3. There is a problem of adhesion at the peeling point of the attached solder.

The result is that the part of the substrate (wafer) or the film formed on the substrate where the wire or ribbon is to be ultrasonically soldered is not preliminarily soldered by ultrasonic welding, and the wire of the solder will be attached Or the experimental results of the case of ultrasonic welding of the welding strip. The result obtained is that the ○-shaped wire or ribbon after pulverization has good tight adhesion, the ○-shaped wire is unstable in tight adhesion, and there is a problem of adhesion at the peeling point of the attached solder.

(3) In the case of "preparatory soldering", "wire or ribbon without solder attached", the following results will be obtained:

1. According to the heat conduction method, the welding materials cannot be connected in the same way.

The result is that the part of the substrate (wafer) or the film formed on the substrate where the wire or ribbon is to be ultrasonically soldered is preliminarily soldered by ultrasonic welding, and the wire without solder is removed. Or the experimental results of the case of ultrasonic welding of the welding strip. Depending on the heat conduction method, the result will be that the welding material cannot be connected in the same way. In other words, because there is no solder attached to the wire or ribbon, and the part of the board to be soldered is prepared for soldering, the soldering iron tip is gently pressed from the wire or ribbon, and ultrasonic welding is performed at the same time. , Therefore, depending on the way of heat conduction to the soldering iron tip, wire or ribbon, and the path of the pre-soldering part on the substrate, it will cause the situation of inconsistent and beautiful soldering. This situation can be solved by welding due to wire or ribbon.

(4) When it is "no preparation welding", "wire or ribbon is not attached to solder", the following results will be obtained:

1. Need to supply solder,

2. The supply of solder combined with the supply of wire or ribbon is not stable in operation,

3. It is difficult to supply the same welding materials.

This result is due to the fact that the wire material or the solder ribbon, and the part of the substrate to be soldered are not prepared for soldering, the wire material or the solder ribbon, and the solder must be supplied at the same time. Therefore, the result obtained is that the solder must be supplied, the supply of the wire or the solder ribbon and the supply of the solder will be unstable, and it is difficult to supply the same solder material.

1: Substrate (silicon substrate)

2: Substrate loading station (substrate preparation heating station)

3: Soldering iron tip

4: Soldering iron tip heating device

5: Ultrasonic oscillation device

6: Solder

7: Solder preparation heating device (T2)

8: Solder sliding device (S2)

31: Soldering iron tip temperature (T3)

32: Soldering iron tip moving device (S1)

Claims (18)

An ultrasonic welding device for welding the substrate or the part of the film formed on the substrate. The ultrasonic welding device has the following devices: a substrate preparation heating device, which prepares the substrate to be welded or the substrate with the film formed Heated to a predetermined temperature, the predetermined temperature is lower than the melting temperature of the solder, the soldering iron tip heating device is the length of the moving direction of the soldering tip close to the portion of the substrate that is prepared to be heated to the predetermined temperature by the substrate preparation heating device The part of the soldering iron tip that is longer than the width of the soldering iron tip is adjusted to a predetermined temperature. The predetermined temperature is the one that will melt the supplied solder under the state of applying ultrasonic waves. The ultrasonic oscillation device is heated by the heating device of the soldering iron tip. The latter part of the soldering iron tip is supplied with ultrasonic wave, and the solder preparation heating device is used to preheat the wire-shaped solder supplied to the aforementioned soldering iron tip to a temperature lower than the temperature at which the wire-shaped solder will melt. The solder sliding device is passed through the aforementioned The solder preparation heating device adjusts the speed at which the pre-heated wire-shaped solder is supplied to the heated soldering iron tip, and the soldering iron tip moving device supplies the wire at a predetermined speed to the heated soldering iron tip close to the substrate While moving the soldering iron tip in the soldering direction at a predetermined speed, the wire solder is preheated by the solder sliding device; wherein the preheated wire solder is melted by the soldering iron tip and ultrasonic waves are applied , Remove the attached matter of the approaching substrate part, and make the molten solder adhere and solder to the substrate part, Moreover, the shape of the aforementioned soldering iron tip part is set as follows: the length of the moving direction of the soldering iron tip is longer than the width of the soldering iron tip, which increases the cross-sectional area and heat capacity to improve the heat conduction to the substrate and lower the temperature of the soldering iron tip. Thermal damage to the film on the substrate or the film in the substrate. The ultrasonic welding device described in the first item of the scope of patent application, wherein the shape of the soldering iron tip part is set as follows: the length of the moving direction of the soldering iron tip is longer than the width of the moving direction of the soldering iron tip, and the cross-sectional area is increased , And improve the transmission of the aforementioned ultrasonic waves to the substrate, and improve the removal of attachments, reduce the ultrasonic oscillation output, and reduce the ultrasonic damage to the film on the substrate or the film in the substrate. In the ultrasonic welding device described in item 2 of the scope of patent application, the ultrasonic oscillation output is set to 2.W to 6W, and ideally 2W. The ultrasonic welding device described in the first item of the scope of patent application, wherein the shape of the soldering iron tip part is: the length of the soldering iron tip in the moving direction is set to 3 to 6 times the width of the soldering iron tip in the moving direction , And cooperate with the period of the undulating length of the moving direction of the soldering iron tip of the substrate to form a solder layer with uniform thickness. The ultrasonic soldering device described in the second item of the scope of patent application, wherein the shape of the soldering iron tip part is: the length of the soldering iron tip in the moving direction is set to 3 to 6 times the width of the soldering iron tip in the moving direction , And cooperate with the period of the undulating length of the moving direction of the soldering iron tip of the substrate to form a solder layer with uniform thickness. The ultrasonic welding device described in item 3 of the scope of patent application, wherein the shape of the soldering iron tip part is: the length of the soldering iron tip in the moving direction is set to 3 to 6 times the width of the soldering iron tip in the moving direction , And cooperate with the period of the undulating length of the moving direction of the soldering iron tip of the substrate to form a solder layer with uniform thickness. The ultrasonic soldering device described in any one of items 1 to 6 of the scope of patent application, wherein the cross-sectional area of the aforementioned preheated wire-shaped solder is increased or decreased, so that the thickness of the solder to the substrate can be reduced as much as possible. Adjust the ground to be thin. The ultrasonic soldering device described in any one of items 1 to 6 in the scope of patent application, wherein the supply speed of the preheated wire solder is set to be the same as the moving speed of the soldering iron tip. The ultrasonic soldering device described in any one of items 1 to 6 of the scope of patent application, wherein the supply speed of the pre-heated wire solder and the moving speed of the soldering iron tip are set in the following manner: The latter is faster to increase the amount of molten solder to increase the thickness of the solder to the substrate, or the former is slower than the latter to reduce the amount of molten solder to make the thickness of the solder to the substrate thinner, and the solder thickness can be adjusted as much as possible Is thin. The ultrasonic soldering device described in any one of items 1 to 6 of the scope of patent application, wherein the moving speed of the soldering iron tip is set to 150 to 200 mm/s to form a uniform and thin solder layer. According to the ultrasonic welding device described in any one of items 1 to 6 in the scope of the patent application, the material of the soldering iron tip or the material for coating the soldering iron tip is made of a material with high hardness and wear resistance. The ultrasonic welding device described in item 11 of the scope of patent application, wherein the aforementioned material is any one of titanium, titanium alloy, silicon, or silicon alloy. The ultrasonic welding device described in item 11 of the scope of patent application, wherein the coating thickness of the soldering iron tip is set to 5 to 15 μm. The ultrasonic welding device described in item 12 of the scope of patent application, wherein the coating thickness of the soldering iron tip is set to 5 to 15 μm. As described in the first item of the patent application, the ultrasonic soldering device uses the tip of the soldering iron to melt the solder previously attached to the soldering tape or wire and apply ultrasonic waves to remove the adherents on the adjacent substrate portion and make The molten solder is attached and soldered to the substrate portion; wherein, the ultrasonic soldering device is equipped with a second soldering iron tip moving device that replaces the solder preparation heating process, the solder sliding device, and the soldering iron tip moving device. This second soldering iron The head moving device uses the soldering iron tip part to press the soldering tape or wire, which is the lead wire that leads the current to the outside to which the solder is attached, against the part of the substrate or the film formed on the substrate, and the soldering iron tip is The person who moves to the welding direction at a predetermined speed. According to the ultrasonic welding device described in the 15th patent application, the wire material is a shape obtained by slightly pulverizing a round wire material. An ultrasonic welding method that welds the substrate or the part of the film formed on the substrate. The ultrasonic welding method is equipped with the following devices: the substrate preparation heating device is the substrate to be welded or the film formed on the substrate The substrate is prepared to be heated to a predetermined temperature, the predetermined temperature is lower than the melting temperature of the solder, the soldering iron tip heating device is the length of the moving direction of the soldering tip close to the portion of the substrate that is prepared to be heated to the predetermined temperature by the substrate preparation heating device The part of the soldering iron tip that is longer than the width of the soldering iron tip is adjusted to a predetermined temperature. The predetermined temperature is the temperature at which the supplied solder will melt under the state of applying ultrasonic waves. The heated soldering iron tip part supplies the aforementioned ultrasonic wave, The solder preheating device is to preheat the wire solder supplied to the soldering iron tip to a temperature lower than the temperature at which the wire solder will melt. The solder sliding device is the wire preheated by the solder preheating device The speed at which the solder is supplied to the heated soldering iron tip part is adjusted, the soldering iron tip moving device, while supplying the wire-shaped solder to the heated soldering iron tip close to the substrate at a predetermined speed, the soldering iron tip is soldered at a predetermined speed Moving in the direction, the aforementioned wire-like solder is pre-heated by the aforementioned solder sliding device; wherein, the pre-heated wire-like solder is melted by the soldering iron tip and ultrasonic waves are applied to the adjacent substrate portion The attachment is removed, and the molten solder is attached and soldered to the substrate portion, and the shape of the soldering iron tip is set to be longer than the width of the soldering tip in the moving direction, increasing the cross-sectional area and heat capacity , And improve the heat conduction to the substrate, reduce the temperature of the soldering iron tip, and reduce the thermal damage to the film on the substrate or the film in the substrate. The ultrasonic soldering method described in item 17 of the scope of patent application uses the tip of a soldering iron to melt the solder previously attached to the soldering tape or wire and apply ultrasonic waves to remove the attached substrates and make The molten solder is attached to and soldered to the portion of the substrate; wherein, the ultrasonic soldering method is provided with a second soldering iron tip moving device that replaces the solder preparation heating process, the solder sliding device, and the soldering iron tip moving device. The soldering iron tip moving device presses the soldering tape or wire, which is a lead wire that draws current to the outside to which solder is attached, against the substrate or the part of the film formed on the substrate with the soldering iron tip part, and makes the soldering iron tip Those who move in the welding direction at a predetermined speed.

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