DE102007042082A1 - Device for soldering solar cells, comprises a laser soldering device, which is displaceably formed along a surface of the solar cell to be soldered, a holding-down device, a cooling device for cooling solder joints, and a camera - Google Patents

Abstract

The device (1) for soldering solar cells (2), comprises a laser soldering device (3), which is displaceably formed along a surface of the solar cell to be soldered, a holding-down device (7) for holding a solder strip on the solar cell, a cooling device for cooling solder joints, and a camera. The holding-down device is adjacently arranged in front to the laser soldering device and in soldering direction (6), is displaceable together with the laser soldering device related to the solar cell, and is a nozzle device having a nozzle with a diameter of 1-3 mm and a heating device (11). The device (1) for soldering solar cells (2), comprises a laser soldering device (3), which is displaceably formed along a surface of the solar cell to be soldered, a holding-down device (7) for holding a solder strip on the solar cell, a cooling device for cooling solder joints, and a camera. The holding-down device is adjacently arranged in front to the laser soldering device and in soldering direction (6), is displaceable together with the laser soldering device related to the solar cell, and is a nozzle device having a nozzle with a diameter of 1-3 mm and a device (11) for heating gases. The temperature of the heated gases is variably adjustable. The holding-down device has a leaf spring and a roller for contacting the solder strip. A further soldering device is arranged on the opposite side of the soldering device. The holding-down device and/or the laser soldering device are obliquely adjustable in the soldering direction. The distance (d) between the laser beam of the laser soldering device and a nozzle opening of the nozzle is 2-10 mm. An independent claim is included for a method for soldering laminar bodies on solar cells.

Description

The The present invention relates to a device for soldering of solar cells and a method of soldering flat Bodies on a substrate, in particular a solar cell.

Separate Solar cells are electrically interconnected in groups and mounted in modules for outdoor installation are suitable. For electrical contacting tinned copper strips soldered to the top and / or bottom of the cells. The solder for forming the soldering zone is tinned by the Band provided. It is a reflow process, in which the tin is melted. The required heat is locally using infrared emitters or hot air nozzles brought in. Due to the unevenness of the band and cell surface, the different thermal expansion coefficient and the relatively thin tin layer, it is necessary cell and tape during the melting process in contact with each other hold. The contacting takes place along the band a plurality of spaced Andrucknadeln. It will be possible Thin pressure pins used to heat through Radiation or hot air stream not to hinder. The pressure pins bring punctiform a mechanical holding force on the Tape up.

Problematic Here is the selective application of force of Andrucknadeln, the in connection with the heat input during soldering can lead to microcracks in the silicon. Such Previous damage is not immediately after soldering ascertainable. The microcracks widen later during operation the thermal load and can cause a failure lead the solar cell. The so soldered Solar cells thus have a high risk of default, the immediate can not be checked after production. The trend towards thinner wafers increases this Risk of pre-damage of the cells.

The Lotband has a higher coefficient of thermal expansion as the solar cell up. This leads to a bulge the bands between the pressure pins during heating up. The result is an incomplete education the solder joint. A permanent secure connection of the Lotbandes with the solar cell can therefore not always guaranteed become.

task The invention is to provide an apparatus and a method, where it is possible to damage the To prevent solar cells during soldering and a reliable To ensure contact of the solder joint.

The The object is achieved with a device having the features of the claim 1 and a method according to claim 13.

advantageous Embodiments are in the respective subclaims specified.

According to the invention a soldering device for soldering solar cells provided, which has a laser soldering, the along a surface of a solar cell to be soldered is formed vefahrbar. The device includes a hold-down device for holding down a solder ribbon on the solar cell, wherein the retaining means adjacent to the laser solder element and in the direction of soldering at the front is arranged. The hold-down device is together with the Laser soldering element with respect to the solar cell movable.

By moving the soldering device and forming the hold-down device becomes a selective introduction of force of the hold-down device avoided on the solar cell, as in the previously known needles the case is. In the invention, it comes to a flat, short-term mechanical stress while holding down the solder ribbon. Of the pressure applied to the solar cell is due to the larger Area much lower. This will cause the formation of microcracks and thus damage to the solar cell avoided.

There the hold-down device is moved along the solder band, be the exposed areas of the solar cell loaded only for a short time. This also reduces the risk of damage to the Solar cell.

A Buckling of the solder ribbon is by the method of soldering or the hold-down device also prevents, as it only to a slight extent of the solder band in the area between the soldering device and the hold-down device comes. In this way, a fully trained Solder between the solar cell and the solder band provided become.

By the use of a laser soldering element is for soldering necessary energy introduced without contact.

in the preferred embodiment of the present invention the holding down of the soldering tape takes place via an air nozzle. Thus, the entire soldering process is gentle, as it performed without contact becomes.

The The invention will be explained by way of example with reference to the drawings. It shows schematically in:

1 the device according to the invention in a side view,

2 a side view of a second embodiment of the device according to the invention,

3 a side view of a third embodiment of the device according to the invention,

4 a side view of a fourth embodiment of the device according to the invention,

5 a side view of a fifth embodiment of the device according to the invention, and

6 a side view of a sixth embodiment of the device according to the invention.

A first embodiment of the soldering device according to the invention 1 for soldering solar cells 2 has a laser soldering device 3 on ( 1 ). The laser soldering device 3 For example, a diode laser with an adjustable spot size of 1 mm to 3 mm and a power of 100 W to 300 W can be. The laser soldering device generates light in a wavelength range of 400 nm to 1000 nm.

The soldering device 3 is on a sled 4 arranged. The sled 4 is on a rail 5 in the direction of soldering 6 by means of a motor (not shown) movable. The traversing speed of the carriage 4 is about 1 m / min.

The rail 5 can be formed with a linear motor (not shown) laterally and in height adjustable.

At the sled 4 is a hold-down device 7 arranged. The hold-down device 7 is in the direction of reeling 6 in front of the laser soldering device 3 arranged. The hold-down device 7 is designed as a nozzle device 7 , To the nozzle device 7 is over a valve 8th a compressed air line 9 connected. The compressed air line 9 is fed via a compressor (not shown) with compressed air. The hold-down device 7 has a heating chamber 10 with a heater 11 and a tubular nozzle 12 on. The tubular nozzle 12 is at the bottom of the hold-down device 7 arranged and with the heating chamber 10 connected. The tubular nozzle has a bend opposite to the direction of soldering in order to position the nozzle opening as close as possible to the soldering point. The diameter of the nozzle opening is between 1 mm and 3 mm and preferably 1.5 mm.

The distance d between the laser beam of the laser soldering device 3 and the nozzle opening of the nozzle 11 the hold-down device 7 stays with the carriage 4 constant and is between 0 mm and 20 mm and preferably between 3 mm and 10 mm.

The soldering device 1 comprises a control device 13 for controlling, the carriage 4 , the rail 5 , the laser soldering device 3 and the hold-down device 7 ,

The operation of the soldering apparatus will be described below 1 for soldering solar cells 2 described.

The solar cells 2 are arranged side by side in a plane and form in this way a solar cell module 14 , Such a solar cell module is formed as a rectangle of a plurality of solar cells. A top surface 15a and a bottom surface 15b the solar cells 2 have a different polarity. On the surfaces 15 the solar cell are formed perpendicular to the soldering conductor tracks.

Parallel to the direction of soldering 6 lie on the top surface 15a and the bottom surface 15b the solar cells 2 two each in the direction of soldering bracelets extending 16 loose. The bracelets 16 are from the edge of the solar cell 2 spaced apart.

The lot band 16 is an elongated copper strip whose top and bottom are coated with solder. The lot band 16 extends from a bottom surface 15a the solar cell 2 to the corresponding differently polarized top surface 15b one in the direction of soldering 6 following solar cell 2 to the conductor tracks on the surfaces of different polarity of each solar cell 2 to connect electrically in series.

The soldering device according to the invention 1 becomes the top of the top surface 15a a solar cell 2 , perpendicular to the direction of soldering, centered over the solder band 16 positioned. Positioning is via the control unit 13 controlled linear motor of the rail 5 , Subsequently, the soldering device 1 lowered to a working level.

About the open valve 8th the nozzle device 7 compressed air flows out of the compressed air line 9 in the heating chamber 10 the nozzle device 7 , In the heating chamber 10 the compressed air is over that from the heater 11 heated heat. The heater 11 or the temperature of the compressed air is via the control device 13 set. The temperature of the compressed air is approximately between 100 ° C and 350 ° C and preferably between 150 ° C and 300 ° C.

The pressure with which the hot compressed air from the nozzle 11 outlet is via the controlled by the control valve 8th set. The volume flow of the outflowing air is about 10 l / min to 100 l / min.

The out of the nozzle 11 the hold-down device 7 escaping hot air impinges on the underneath arranged area of the soldering tape 16 and presses it with a holding force of about 0.5 N to 1.5 N and preferably 1 N areally on the upper side surface arranged thereunder 15a a solar cell 2 ,

The control device 13 controls the laser soldering device 3 at. The laser soldering device 3 generates a laser beam with a wavelength of 400 nm to 1000 nm and preferably with a wavelength of 800 nm to 1000 nm.

The laser beam strikes the underneath area of the solder ribbon 16 the one through from the nozzle 11 applied holding force on the top surface 15a the solar cell is pressed. The amount of the hold-down force is from the controller 13 set. The laser beam melts the solder on the top and bottom of the plumb band 16 on. In this way, a Lötverbin is training between the tracks of the top surface 15a the solar cell 2 and the solder band 16 produced.

With the out of the nozzle 12 escaping hot air is the soldering tape 16 heated immediately before the soldering process. As a result, with the laser beam of the laser soldering 3 reduced power requirement.

Once the solder on the solder tape 16 is sufficiently liquefied controls the controller 13 the sled 4 at. The carriage moves the soldering device 2 in the direction of soldering 6 along the rail 5 at a constant speed of about 1 m / min. As a result, the tracks of the top surface 15a with the solder ribbon arranged above it 16 soldered. The controller stops the carriage when the solder ribbon with all traces of the top surface 15a the solar cell 2 is completely soldered.

Then the laser soldering device 3 and the hold-down device 7 the soldering device 1 from the control unit 13 off. The sled 4 moves the soldering device 1 over the transition area between two solar cells 2 ,

The process repeats until all traces on the top surfaces 15a the solar cells 2 with all tracks on the underside surfaces 15b the solar cells 2 are connected. For soldering on the underside surfaces 15b arranged conductor tracks become the solar cells 2 turned over and soldered according to the method just described. In this way, the solar cells 2 of the solar cell module 14 electrically connected in series.

Instead of the compressed air can also be another suitable gas in the nozzle device 7 be used.

In a second embodiment ( 2 ) of the soldering device according to the invention 1 is on the bottom of the solar cell module 14 a second soldering device 1b arranged. The second soldering device 1b is identical to the first soldering device 1a and solder it on the bottom surface 15b the solar cell 2 arranged conductor tracks with the soldering tape 16 , The second soldering device 1b is also about a sled 4b on a rail 5a four mobile. The control unit 13 is in this embodiment with the first soldering device 1a and the second soldering device 1b connected.

This makes it possible solder joints on the top surface 15a and on the bottom surface 15b offset in time, ie one after the other, without the solar cell module 14 must be turned around. Otherwise, the method is analogous to the method described above. In addition, it is possible the top and bottom offset locally, that is to be soldered successively spaced. This has the advantage that not so much heat is applied all at once in the same area. As a result, a pre-damage of the cells is avoided. The hold-down device 7 can also be used to generate a counterforce to the opposite soldering, if this is due to the static nature (eg risk of deflection) of the solar cell 2 is appropriate.

In a third embodiment ( 3 ) of the soldering device according to the invention 1 is the hold-down device 7 also on the sledge 4 arranged. The hold-down device 7 has an L-shaped spring receptacle 17 for receiving a leaf spring 18 on. The leaf spring 18 extends opposite to the direction of soldering 6 down to the rear and at the lower end has an upwardly open semicircular hold-down section. The holddown section is on the solder band 16 on and presses this area with a hold-down force of about 0.5 N to 1.5 N and preferably 1 N on the surface arranged underneath 15 a solar cell 2 , The hold-down force can be controlled by the spring force of the leaf spring 18 be set. The leaf spring 18 is band-shaped and made of spring steel educated.

When moving the soldering device 1 pushes the leaf spring in the direction of soldering 6 in front of the laser soldering device 3 located area of the solder band 16 flat on the solar cell 2 , Otherwise, the method runs analogously to the method described with reference to the first embodiment.

In a fourth embodiment ( 4 ) of the soldering device according to the invention 1a is on the bottom of the solar cell module 14 a second soldering device 1b arranged. The second soldering device 1 is identical in construction to the first soldering device 1a of the third embodiment and soldered on the bottom of the solar cell 2 arranged areas 15b with the soldering tape 16 ,

from that result in the same advantages as they already in the second embodiment are described.

The Leaf spring of the third and fourth embodiment can also be designed in any other form.

The hold-down device 7 can also be designed as a height-adjustable role.

In a fifth embodiment ( 5 ) of the soldering device according to the invention 1 is the nozzle 12 the hold-down device 7 against the direction of soldering 6 arranged obliquely rearward to the air jet closer or directly in the area of the laser soldering 3 to be arranged (position I). This reduces the risk of soldering. It can also be provided the laser or its laser beam in the direction of soldering 6 to be arranged diagonally forward (position II). Furthermore, the soldering device 1 be formed such that the hold-down device 7 and the laser soldering device 3 are arranged obliquely in the manner just described (position III).

In a sixth embodiment ( 6 ) of the soldering device according to the invention 1 is 4 the laser soldering device 3 formed such that the laser beam obliquely in the direction of soldering 6 is directed forward. In the direction of soldering 6 in front of the laser soldering device 3 is a camera 19 intended. In the direction of soldering 6 in front of the camera 19 is the hold-down device 7 arranged. The nozzle 12 is oblique in the direction of reeling 6 directed backwards. At the laser soldering device 3 and the hold-down device 7 Actuators (not shown) may be provided to the inclination angle of the laser soldering 3 and the hold-down device 7 to adjust.

The control device 13 has an automatic image processing. The image processing is designed such that it can automatically recognize shapes and / or edges. For example, edge detection is off Bernd Jähne "Digital Image Processing", published by Springer Verlag, 6th edition, chapter 12 known. This automatic detection of edges and shapes is used to detect the areas to be soldered. The control device 13 automatically controls the soldering process as a function of the detected shapes and edges, ie that when an edge is exceeded after an area to be soldered starts automatically the soldering process (hold-down device and laser soldering) starts and the soldering process is automatically stopped when leaving this area.

Preferably, this control method is designed such that a laser beam with reduced energy is emitted outside of the areas to be soldered. As a result, by means of image processing, the position of the soldering device 1 be checked with respect to the object to be soldered and optionally adjusted.

at a semi-automatic control, an operator can use the laser light detect if the laser beam is located in a region to be soldered and accordingly start or stop the soldering process.

This control device 13 is particularly suitable in connection with a traversing device for automatically moving the carriage at least in a plane parallel to the soldering object. This allows fully automatic complex soldering operations to be performed.

This Embodiment of the present invention corresponds otherwise the one already described above.

By controlling the servomotors via the control device 13 can the inclination angle of the laser soldering 3 and the hold-down device 7 be set exactly to the desired position.

It is also possible the quality of the solder joint produced by the camera 19 and automatic image processing.

In the soldering device according to the invention according to the embodiments 1 to 6, a cooling device (not shown) may be arranged on the carriage in the direction of soldering behind the laser soldering. By means of this cooling device, the solder joint can be cooled directly in the connection to fix the solder band faster on the solar cell. This results in a shorter loose area between the support point of Niederhaltereinrich tion and the already soldered section of the solar cell. As a result, the risk of soldering error is further reduced.

With the device according to the invention can Even solar cells only on their underside strip conductors have to be soldered with solder ribbons. at Such solar cells are contact areas at the in the direction of soldering formed lateral edges. The bracelets with which such solar cells have to be soldered At their lateral edges contact tabs on the with be soldered to the contact areas of the solar cells. One Partial soldering of such solar cells is with the Device according to the invention according to one of the embodiments 1 to 5 possible. But for such solar cells is in particular a device according to the sixth Embodiment suitable because the device, about the camera, the image processing and the laser beam decreased Intensity, exactly the areas detected in which the Laser soldering device and the hold-down device or have to be switched off.

The Inventive device and the invention Methods are particularly suitable for soldering solar cells. However, they can also be used to any areal Solder body on a substrate.

By moving the soldering device and forming the hold-down device becomes a selective introduction of force of the hold-down device avoided on the solar cell, as in the previously known needles the case was. In the invention, it comes to a flat, short-term mechanical stress while holding down the solder ribbon. Of the pressure exerted by the solar cell is due to the larger area much lower. This will cause the formation of microcracks and thus avoid damage to the solar cell. Also moving the soldering device helps that individual areas during the soldering process not be overburdened.

A Buckling of the solder ribbon is by the method of soldering or the hold-down device also prevents, as it only to a slight extent of the solder band in the area between the soldering device and the hold-down device comes. In this way, a fully trained Solder between the solar cell and the solder band provided become.

1

soldering device

2

solar cell

3

Laserlöteinrichtung

4

carriage

5

rail

6

soldering direction

7

Hold-down device

8th

Valve

9

Compressed air line

10

heating chamber

11

heater

12

jet

13

control device

14

solar cell module

15

surface

16

solder strip

17

spring mount

18

leaf spring

19

camera

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - Bernd Jähne "Digital Image Processing", published by Springer Verlag, 6th edition, chapter 12 [0052]

Claims (23)

Soldering device for soldering solar cells with, a laser soldering device ( 3 ) running along a surface ( 15 ) of a solar cell to be soldered ( 2 ) is formed movable, and a hold-down device ( 7 ) for holding down a plumb band ( 16 ) on the solar cell ( 2 ), the hold-down device ( 7 ) adjacent to the laser soldering device ( 3 ) and in the direction of 6 ) is arranged at the front and together with the laser soldering device ( 3 ) with respect to the solar cell ( 2 ) is movable. Soldering device according to claim 1, characterized in that the hold-down device ( 7 ) a nozzle device with nozzle ( 12 ). Soldering device according to claim 1 or 2, characterized in that the diameter of the nozzle ( 12 ) Is 1 mm to 3 mm. Soldering device according to one of the claims 1 to 3, characterized in that the nozzle device a heater for heating a gas. Soldering device according to one of the claims 1 to 4, characterized in that the temperature of the heated Gas is variably adjustable. Soldering device according to one of claims 1 to 5, characterized in that the hold-down device ( 7 ) a leaf spring ( 18 ) having. Soldering device according to one of claims 1 to 6, characterized in that the hold-down device ( 7 ) a roll for contacting the solder strips ( 16 ) having. Soldering device according to one of the claims 1 to 7, characterized in that a cooling device provided for subsequent cooling of the solder joint is. Soldering device according to one of claims 1 to 8, characterized in that on the opposite side of the soldering device ( 1a ) a second soldering device ( 1b ) is arranged. Soldering device according to one of claims 1 to 9, characterized in that the hold-down device ( 7 ) and / or the laser soldering device ( 3 ) in the direction of soldering ( 6 ) are diagonally adjustable. Device according to one of claims 1 to 10, characterized in that the soldering device ( 1 ) has a camera. Device according to one of claims 1 to 11, characterized in that the distance (d) between the laser beam of the laser soldering device ( 3 ) and the nozzle opening of the nozzle ( 11 ) is between 0 mm and 30 mm and preferably between 2 mm and 10 mm. Method for soldering flat bodies to a substrate, in particular solar cells, in which the flat body coated with a solder ( 16 ) from a hold-down device ( 7 ) on the substrate ( 2 ) and that on the Lotband ( 16 ) applied solder from a laser soldering device ( 3 ) is melted to an electrical connection between the substrate ( 2 ) and the body ( 16 ), wherein the hold-down device ( 7 ) adjacent to the laser soldering device ( 3 ) and in the direction of 6 ) is arranged at the front and together with the laser soldering device ( 3 ) with respect to the substrate ( 2 ) is movable. Method according to claim 13, characterized in that the hold-down device ( 7 ) holds down the body with a force between 0.5 N and 1.5 N, and preferably less than 1 N. Method according to one of claims 13 to 14, characterized in that by means of a heated gas the point at which the solder joint is to be formed is heated. Method according to one of claims 13 to 15, characterized in that the temperature of the heated Gas between 100 ° C and 350 ° C and preferably between 150 ° C and 300 ° C. Method according to one of claims 13 to 16, characterized in that the gas with a throughput of 10 l / min is blown out to 100 l / min. Method according to one of claims 13 to 17, characterized in that a second, the first opposite hold-down device ( 7b ) a counterforce to the contact pressure of the first hold-down device ( 7a ) to generate a balance of power. Method according to one of claims 13 to 18, characterized in that two opposing soldering devices ( 1a . 1b ) are temporally and / or locally offset from one another. Method according to one of claims 13 to 19, characterized in that the soldering device ( 1 ) at a rate of 0.1 m / min to 2.5 m / min and preferably at a rate of 1 m / min. Method according to one of claims 13 to 20, characterized in that a camera ( 19 ) receives the solder joint and from there parameters for controlling the soldering device ( 1 ) be determined. Method according to one of claims 13 to 21, characterized in that a device according to any one of claims 1 to 13 is used. Use of the soldering device according to one of Claims 1 to 12, for soldering a solar cell.