JPH0472775A - Solar cell provided with cover glass and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the structure of a solar cell having a cover glass adhered to its surface and a method for manufacturing the same.

[Prior Art] A cover glass is used to bond the surface of a solar cell C/L/ (hereinafter also referred to as a cell) in order to block radiation exposure and ultraviolet rays. It is especially used in solar cells for space applications. The thickness of the adhesive is to be made as thin as possible to meet the demand for weight reduction, and to improve reliability in order to prevent adhesive peeling from the periphery of the cell due to thermal stress caused by the temperature cycle environment. There are cases where the thickness is made as thick as possible to meet the requirements, and cases where an intermediate thickness is used to satisfy both requirements.

In addition, the method of applying adhesive to adhere the cover glass to the cell is to use a syringe to drop one or several drops of the adhesive onto the barrel or cover glass, and then glue the cell and cover glass together. There are manufacturing methods that spread the adhesive, and methods that use a mesh screen with a constant aperture ratio to apply the adhesive to the entire cell or cover glass.

The adhesive thickness of a cell with a cover glass manufactured by the adhesive application method using a syringe depends on the shape of the cell and cover glass, especially since the dropped adhesive is spread and bonded by the weight of the cell or cover glass. It is greatly influenced by the state of anti-shi. The thickness of the adhesive is controlled by adjusting the amount discharged per drop using a syringe.

The adhesive thickness of the cover glass-equipped cell manufactured by the adhesive application method using a mesh screen with a constant aperture ratio is almost uniform. The adhesive thickness is controlled by adjusting the aperture ratio of the mesh screen.

FIG. 7 to FIG. 9 are diagrams illustrating a case where a cell and a cover glass are bonded by dropping an adhesive using a syringe. As shown in the cross-sectional view in FIG. 70 onto the surface and press and bond them together,
The thickness of the adhesive is greatly influenced by the shape of the cell 8 and the cover glass 7, especially the warp, and as shown in the plan view of FIG. It is almost elliptical with the center at . 9th
The figure is a sectional view taken along YY' in FIG. 8, and the thickness of the adhesive 6 is thinner at the center and slightly thicker at the periphery. In the figure, the cover glass 7 is curved and the C/L/8 is flat, but the opposite case or both may be curved. In these figures, 2 is an interconnector, 14
#i is the front electrode.

Table 1 below shows a case in which a cover glass 7 with a thickness of 100μ steel and a size of 2X4511 is bonded to a cell 8 with a size of 2X4a and a thickness of 50μ having a convex warp in the direction of the cover glass as shown in FIG. The data on the overall thickness of the cover glass-equipped cell 1 when A-1 in Table 1 is the first
This corresponds to each point A-I of the cell jv8 shown in FIG.

Table 1 Cell thickness: 60 μm Sea bream Cover glass thickness: 100 μm As is clear from Table 1, the thickness of the adhesive 6 in the central part of the cell 8 is approximately 10 to 87 μm, while the thickness of the adhesive 6 in the peripheral part A, B
, C, E, F, and G have a thickness of 50 to 187 μm.

A solar battery cell with a cover glass having this structure was subjected to a temperature cycle test (-180°C to +140"0) simulating the temperature cycle environment in space.

It has been confirmed that it can sufficiently withstand 1 hour hold and 5 cycles (1V).

In addition, when a mesh screen with a constant aperture ratio is used and the adhesive 6 is applied to the cover glass 7 or the cells 8, the adhesive 6 is applied as shown in the cross-sectional view of FIG. With the thickness of No. 6, a fairly uniform thickness can be obtained. Table 2 below shows data on the total thickness of the cell with a cover glass when a cover glass 7 with a thickness of 100 μm and a size of 4×6-m1 is adhered to a cell 8 with a thickness of 50 μm and a size of 4×Gcg1. . A' to 1' in Table 2 correspond to points A' to A' of cell 8 shown in FIG.

Table 2: Cell thickness: 50 μm Cover glass: 100 μm As shown in Table 2, according to this method, the thickness of the adhesive is uniform throughout the cell, and is as thin as 14 to 75 μm.
You can see that

(Problems to be Solved by the Invention) In the method of dropping adhesive using a syringe as shown in Figs. There is a manufacturing problem in which the adhesive does not spread throughout the cell, and when the adhesive is thinned to reduce weight, the shear stress generated at the periphery of the cell increases, leading to repeated temperature cycles. Unfortunately, adhesive peeling may occur.

In addition, when using a mesh screen with a constant opening ratio as shown in Fig. 10, the thickness of the adhesive 6 as a whole has a smaller deviation than when using a syringe, but the weight is reduced. When the thickness of the adhesive 6 is reduced due to demand, the thickness of the adhesive 6, especially on the interconnector, becomes even thinner by the thickness of the interconnector. Therefore, if the thermal stress caused by temperature cycles is large, adhesive peeling is likely to occur. Furthermore, if the thickness of the adhesive in the vicinity of the interconnector 2 is ensured to be above a certain level, the overall weight increases, and the weight reduction required for recent solar cells with cover glasses cannot be achieved.

As described above, it has been difficult to satisfy both the requirements for weight reduction and reliability.

(Means for Solving the Problems) In the present invention, in order to solve the above-mentioned problems, the thickness of the adhesive at the periphery of the adhesive surface between the cell and the cover glass is made thicker than the thickness of the adhesive on the inner adhesive surface. I let it happen.

In addition, the adhesive is applied to either the solar cell or the cover glass through a mesh screen with a constant aperture ratio whose surface is masked with a specific pattern, and the adhesive is applied to either the solar cell or the cover glass. The method is characterized in that the cell and the cover glass are bonded together.

(Function) According to the present invention, by increasing the thickness of the adhesive in the portion where a large shear stress acts, it is possible to increase the adhesive strength and at the same time reduce the weight.

[Embodiment] FIG. 1 is a plan view of an embodiment of the present invention, and as shown in the cross-sectional view of FIG. Let L' be the thickness of the adhesive in the peripheral area B of For example, when t4 is t4, t<1. ≦(t3-ti)...(1)
The relationship is as follows. FIG. 2 is a sectional view taken along line XX' in FIG. 1. The thickness t3 also includes the thickness of the front electrode 14. The thickness of the front electrode 14 is usually extremely thin. According to this structure, the thickness of the adhesive in area A inside the cell is made as thin as possible, and in order to prevent the adhesive from peeling off at the periphery of the cell due to thermal stress caused by the temperature cycle environment in space, The thickness of the adhesive in areas B and C is increased. In particular, the thickness of the adhesive near the peripheral area C including the connection part of the interconnector 2 [t3-14] is
It is desirable that the thickness of the adhesive in the other peripheral areas is even thicker than the thickness t2.

Such a change in the thickness of the adhesive is performed by applying the adhesive to the surface of the cell 8 or the surface of the cover glass 7 using a mesh screen 9 as shown in FIG. . The aperture ratio of the area a inside the mesh screen 9 corresponding to the area A inside the mesh screen 9 corresponding to the area A inside the cover glass The aperture ratio of the area around the mesh screen 90 corresponding to B is P2, and the area around the mesh screen 9 corresponding to the peripheral area C on the side where the interconnector 2 of the cell 8 or the cover glass 7 is located. If the aperture ratio of C is p, then for example pl<p2<p3...(2)
shall be. When adhesive is applied using such a mesh screen, the desired thickness of adhesive is applied to each of areas A, B, and C, but the boundary between these areas is sequentially applied with an intermediate thickness. Change. The area between area A and area B is area (A, B), and the area between area B and area C is area CB, C).
, the middle between region A and region C is defined as region (A, C), and the middle between region A, region B, and region C is defined as region (A, B, C).

In addition to equation (1), these relationships are as follows: 1, - Thickness of regions (A, B) ≦ t2 ≦ Thickness of regions (B, C) ≦ [3 ... (3) and t1 ≦ region ( Thickness of A, C)≦t3...(4) and t1≦Thickness of region (A, B, C)≦t,...(5)
shall be.

Table 8 below shows an example of data on the overall thickness of a solar cell with a cover glass manufactured as a prototype according to the present invention. Same as the example in Tables 1 and 2, the cell thickness is 50
The thickness of the cover glass is 100μ. however,
The area for both cases was 4 x 6 cycles. A' to I' in Table 8
correspond to points A'' to 1' in FIG.

Table 8 Cell thickness: 50 μm Cover glass thickness: 100 μm As is clear from Table 8, the thickness of the adhesive at, for example, point E' of the 12th factor in the inner area A of the cell is as thin as 2 to 15 μm, and The thickness of the adhesive at points B'C', F', H', and I' in the peripheral area B, for example, is 44 to 88 μm thick, and the thickness of the adhesive at points A', D', and G' in the peripheral area C, for example, is relatively thick. The thickness of the adhesive is as thick as 82 to 118 microns. Further, if the thickness of the interconnector is 80μ, the thickness of the adhesive on the interconnector is 52 to 88μ, which is within the range of formulas (1) to (5) described above. It has been confirmed that the solar battery cell with a cover glass having this structure does not cause adhesive peeling even in the above-mentioned temperature cycle test.

FIG. 4 is a diagram for explaining another adhesive application method of the present invention. In the figure, mesh screen 1 with a constant aperture ratio
Masking 16 with a specific pattern is applied on 5. As shown in the figure, the masking rate of the masking 16 covering the mesh screen 15 is changed depending on the thickness of the adhesive 6 required at each location on the cell 8.

Furthermore, the aperture ratio of the mesh screen 15 is increased compared to the conventional manufacturing method using a mesh screen. The aperture ratio of a conventional mesh screen, indicated by mesh f in FIG. 6, which will be described later, is around 470, whereas in this embodiment it is, for example, 4150 to 190.

In FIG. 4, A' to 1' correspond to A' to ■' in FIG. It is set so that it becomes smaller in the order of the periphery. As a result, the adhesive 6 on the cell/L/8 is applied thickly in this order: the center of the cell, the periphery without an interconnector, and the periphery with an interconnector.

FIG. 6 shows the resin thickness of the adhesive when the adhesive 6 is applied to the cell 8 shown in FIG. 12 using the mesh screen 15 provided with the masking 16 shown in FIG. The size of the applied cell 8 is 40■xaos*, and the thickness is 50μ
It's a horse. In FIG. 5, measurement points A' to 1' correspond to A' to I' in FIG. 12.

From FIG. 5, the thickness of the adhesive resin in the peripheral part of the cell 8 (parts other than E') is thicker, and the interconnector part A'-D'
, D', and D'-G' are particularly thick, while E', which is the central part of the cell 8, is thin. It can thus be seen that the adhesive 6 is applied as shown in FIG.

FIG. 6 is a diagram showing the relationship between the aperture ratio of the mesh screen alone and the adhesive resin thickness.

According to FIG. 6, the adhesive resin thickness at each measurement point of C/L/8 shown in FIG. It can be seen that the adhesive resin thickness corresponds to the case where the mesh screen of f150 is used alone, and the mesh screen of ATO is used alone at the center of the cell in section E'.

In this way, by applying a specific masking pattern to a mesh screen with a constant aperture ratio, the thickness of the adhesive can be made to any desired thickness at any location, just as if multiple mesh screens were used. It became possible.

For example, in this embodiment, the center of the cell 8 is thinned,
Although the peripheral portion is made thicker than the central portion and the interconnector portion is made thicker, other thickness shapes can be easily realized by changing the masking pattern.

As described above, an appropriate adhesive thickness determined by the size and thickness of the cell and the thickness of the cover glass can be provided at the required location.

In addition, in this embodiment, the solar cell 8 and the cover glass 7
At the time of adhesion, the adhesive 6 was applied to the solar cell 8 side, but it may be applied to the cover glass 7 side.

The fact that the structure according to the present invention is highly reliable with respect to adhesive peeling can be explained using a simple -dimensional stress equation as follows.

In FIG. 18, it is assumed that the cover glass 7 and the cell 8 have high rigidity and are not affected by mutual displacement via the adhesive 6. It is also assumed that the adhesive 6 has low rigidity and is affected by displacement of the cover glass 7 and cells 8. The thickness of each of the length of the cover glass 7, adhesive 6, and cell 8 is T1. Let T,,T,. Further, the transverse elastic constant of the adhesive 6 is G, and the X-axis stress of the cover glass 7 and the cell 8 is σ1. Let it be σ2. It is also assumed that the interfacial shear forces between the cover glass 7 and the adhesive 6 of the cell 8 are equal.

At this time When the solution to Equation 01 is found using Equation 09, σ2−−mσ1 Here, X indicates the distance from the center of the cell.

Each stress is expressed by the formula below.

m-'r's, ,,,, n-\.

Organized as a function of adhesive thickness T3, E, ,E,
represent the Young's modulus of cover glass 7 and cell 8, respectively.

ul, u2 are the displacements of each layer in the X-axis direction, α1. a2 indicates the linear expansion coefficient of each layer, and ΔT indicates the amount of temperature change.

becomes.

Figure 14 shows the thickness of C/I/8, the thickness of cover glass 7,
A relative comparison of the shear center force τ when the physical property values of each constituent material are arbitrarily fixed is shown below based on the thickness T of the adhesive 6.

and distance X from the center of cell 8 are shown as parameters. It can be seen that as the thickness T1 of the adhesive becomes smaller, and as the cell size becomes larger, the shear stress generated in the adhesive 6 around the cell increases exponentially.

FIG. 15 shows a relative comparison of the cell edge interface shear stress when the thickness of cell/L'8 and the amount of temperature change are arbitrarily fixed, using the thickness of the cover glass 7 as a parameter.

It can be seen from FIG. 15 that the thicker the shell 8 and the thicker the cover glass 7, the greater the interfacial shear stress.

The above explanation is based on an example using a mesh screen, but it may also be realized by discharging adhesive from a narrow nozzle and obtaining an adhesive distribution that satisfies the condition of formula (2).

(Effects of the Invention) As described above, in the solar cell with a cover glass according to the present invention, reliability against heat stress is improved because the thickness of the adhesive in the peripheral part is thick, and the thickness of the adhesive inside the cell is improved. Since it can be made thinner, weight can be reduced. This is effective in reducing the weight of the adhesive even as solar cells become larger.

[Brief explanation of drawings]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a sectional view taken along line xx' in FIG. 1, FIG. 8 is a plan view of a mesh screen used in the present invention, and FIG. FIG. 5 is a graph showing the measurement results of the adhesive resin thickness by the adhesive application method explained in FIG. 4. FIG. A graph showing the relationship between the aperture ratio and the thickness of the adhesive resin, FIG. 7 is a cross-sectional view of an example of the adhesion state between the cover glass and the cell, FIG. 8 is a plan view of a conventional example, and FIG. 9 is its Y- Y' sectional view, FIG. 10 is a sectional view of another conventional example, FIG. 11 is a plan view showing the position of each data measurement point of the example of FIG. 8, and FIG. 12 is a cross-sectional view of the example of FIG. 10. A plan view showing the position of each point of data measurement, Fig. 18 is a perspective view for explaining the stress formula, Fig. 14 is a graph showing the relationship between shear stress and distance from the cell center, and Fig. 15 is the cell edge part. It is a graph showing the relationship between interfacial shear stress and cover glass thickness. DESCRIPTION OF SYMBOLS 1... Solar cell with cover glass, 2... Ink connector, 6... Adhesive, 7... Cover glass, 8
... Cell, 18 ... Adhesive contour line, 14 ... Surface electrode.

Claims (3)

[Claims] (1) The thickness of the adhesive on the adhesive surface between the solar cell and the cover glass is calculated as follows: Adhesive thickness at the center of the cell < Adhesive thickness at the periphery without interconnectors ≤ Periphery with interconnectors A solar cell with a cover glass characterized by having an adhesive thickness of . (2) On either the solar cell or the cover glass,
Adhesive is applied through a mesh screen with a constant aperture ratio whose surface is masked with a specific pattern.
A method for manufacturing a solar cell with a cover glass, comprising bonding the solar cell and the cover glass. (3) A patent claim characterized in that masking is performed on a mesh screen having a constant aperture ratio, with the masking ratio decreasing in the order of the cell center, the peripheral part without an interconnector, and the peripheral part with an interconnector. Range 2nd
A method for producing a solar cell with a cover glass as described in 2.