TWI702197B - Glass frit, method for manufacturing glass frit, and aluminium paste - Google Patents

Abstract

The present invention relates to a glass frit for use in an aluminum paste for forming an aluminum electrode on the back surface of a solar cell or the like, a method for manufacturing a glass frit, and an aluminum paste. The present invention aims to realize the manufacturing of a glass frit which does not contain metals such as iron, copper, nickel, which can melt at a low temperature necessary for the manufacture of a solar cell or the like, and whose main components are only vanadium and barium.

The glass frit of the present invention is manufactured by heating 55 to 80 mol% of vanadium V₂O₅ and 15 to 30 mol% of barium BaO as the main materials, or 10 to 55 mol% of vanadium V₂O₅ and 10 to 40 mol% of barium BaO as the main materials to produce molten glass, and pulverizing the fragments which are formed by rapidly cooling the molten glass, wherein the glass frit is melted at 650℃ or less.

Description

Glass frit, glass frit manufacturing method and aluminum paste

The present invention relates to a glass frit used in an aluminum paste for forming an aluminum electrode on the back of a solar cell, a method for manufacturing the glass frit, and an aluminum paste.

In the past, the development of solar cells, one of the renewable energy sources, was based on the semiconductor technology of the protagonist of the 20th century. It is an important development that governs the global level of human survival. The subject of its development is not only the efficiency of converting sunlight into electrical energy, but also the subject of reducing manufacturing costs and being pollution-free. In efforts to achieve these development issues, it is generally believed that reducing or eliminating the use of silver (Ag) and lead (Pb) used in electrodes is particularly important.

For example, aluminum paste is coated and sintered on the entire back surface of a silicon substrate (p-type) constituting a solar cell to form an aluminum electrode (p+), and leads are welded there.

However, when the lead wire is directly welded to the aluminum electrode, its tensile strength is weak. Therefore, in the past, multiple holes were excavated in the aluminum electrode, and silver paste was applied and sintered there, and the lead wire was welded there.

The aluminum electrode formed by coating and sintering aluminum paste on the back of the solar cell is exposed to severe conditions for a long time. When iron, copper, nickel, chromium and other metals are present in the glass frit constituting the aluminum paste, the Metal has the possibility of degrading the performance of solar cells.

Therefore, it is desired to produce a novel glass frit that does not contain such iron and other materials that cause adverse effects in the glass frit constituting the aluminum paste and the like, and will melt at low temperatures.

The inventors of the present invention made it possible to produce a glass frit that does not contain metals such as iron, copper, nickel, and chromium, melts at a low temperature necessary for the production of solar cells, etc., and has only vanadium and barium as its main components.

Therefore, the present invention is to produce a glass frit that is mixed into the conductive paste that is coated and sintered on the substrate to form a conductive electrode. The glass frit is: 55 to 80 mole% of vanadium V ₂ O ₅ And 15 to 30 mol% of barium BaO is heated as the main material to produce molten glass, and the fragments formed by rapid cooling of the molten glass are crushed to produce the glass frit that melts at 650°C or lower.

At this time, the system should not contain iron, copper, nickel, and chromium.

In addition, one or more of 0 to 15 mol% aluminum Al ₂ O ₃ , 0 to 10 mol% boron B ₂ O ₃ and 0 to 7 mol% silicon SiO _{2 are} mixed into the main material as additives and Heating produces molten glass.

Furthermore, aluminum paste is used as the conductive paste.

In addition, the aforementioned coating and sintering on the substrate to form the conductive electrode is to apply and sinter the substrate of the solar cell to form the conductive aluminum electrode.

Furthermore, the present invention is to produce a glass frit that is mixed into a conductive paste that is coated and sintered on a substrate to form a conductive electrode. The glass frit is: 10 to 55 mol% of vanadium V ₂ O ₅ And 10-40 mol% of barium BaO is heated as a main material to produce molten glass, and the fragments formed by rapid cooling of the molten glass are crushed to produce the glass frit at 650°C or lower.

In addition, 1 to 10 mol% of aluminum Al ₂ O ₃ and 1 to 20 mol% of boron B ₂ O _{3 are} mixed into the main material as additives and heated to produce the molten glass.

In addition, 5 to 20 mol% of phosphorus P ₂ O ₅ and 5 to 20 mol% of calcium CaO are mixed into the main material as additives and heated to produce the aforementioned molten glass.

In addition, calcium CaO added together with phosphorus P ₂ O _{5 which} is an additive is set as a compound with one or more of phosphorus and alkaline earth metals.

Furthermore, the aforementioned calcium CaO added together with phosphorus P ₂ O ₅ , which is an additive, is set to be tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or a partial compound with one or more of phosphorus and alkaline earth metals. Calcium phosphate Ca(PO ₃ ) ₂ .

As mentioned above, the present invention can produce a glass frit that does not contain iron, copper, nickel, chromium and other metals, and will melt at the low temperature necessary for the manufacture of solar cells, that is, below 650°C, and whose main components are only vanadium and barium. . These glass frits have the following characteristics.

(1) The glass frit may not contain iron, copper, nickel, chromium and other substances that can cause adverse effects under the harsh conditions of solar cells. Thereby, it is possible to eliminate the deterioration of the life of the solar cell due to the inclusion of iron or the like.

(2) It is possible to achieve the lower melting point of 650°C or lower, which is necessary for the use of aluminum paste. Thereby, it is possible to sinter at a low melting point, and it is possible to realize the glass frit of the aluminum paste that can be used to form the aluminum electrode on the back of the solar cell.

(3) The composition of vanadium and barium can eliminate the warpage of the solar cell substrate during aluminum paste sintering.

(4) Adding phosphorus P ₂ O ₅ and alkaline earth metals (for example, calcium CaO) can improve I/V characteristics and adhesion.

(5) Aluminum Al ₂ O ₃ and boron B ₂ O ₃ are added in a predetermined blending to easily vitrify.

Figure 1 is a manufacturing flow chart of the ABS glass of the present invention.

Figure 2 is an example of manufacturing samples of the ABS glass of the present invention.

Fig. 3 shows an example of the glass frit for aluminum paste for solar cells of the present invention.

Fig. 4 is an explanatory diagram of an example of the upper and lower limit of each component range of the ABS glass of the present invention.

Fig. 5 is an explanatory diagram of the glass frit for firing aluminum electrodes for solar cells of the present invention.

Fig. 6 is an overview photograph example of the ABS glass of the present invention.

Figure 7 is the manufacturing flow chart (Part 2) of the ABS glass of the present invention.

Fig. 8 is an example of manufacturing samples of the ABS glass of the present invention (Part 2).

Fig. 9 shows an example of the glass frit for aluminum paste for solar cells of the present invention (Part 2).

Fig. 10 is an explanatory diagram of an example of the upper and lower limit of each component range of the ABS glass of the present invention (No. 2).

Fig. 11 is an explanatory diagram of the glass frit for firing aluminum electrodes for solar cells of the present invention (Part 2).

Figure 12 is an explanatory diagram of the aluminum paste of the present invention.

Figure 13 is a manufacturing flow chart of the aluminum paste of the present invention.

Figure 14 is a flow chart of the calcination of the aluminum paste of the present invention.

[Example 1]

Figure 1 shows a manufacturing flow chart of the ABS glass (Art Beam solar cell glass) of the present invention.

In Fig. 1, the S1 system prepares and melts glass raw materials (900°C to 1200°C) (after the electric furnace temperature rises, it is added and left for 1 hour). This is when the temperature of the electric furnace rises to the optimal temperature determined by the experiment in the range of 900°C to 1200°C, put the prepared glass material into the crucible, insert, dissolve and leave it for 1 hour. In addition, the raw material put in the crucible may be melted by raising the temperature to a predetermined temperature in an electric furnace and left for 1 hour. In the experiment, the glass raw material is, for example, the following shown in Fig. 2 described later.

S2 produces glass fragments (3 to 5mm). This is as described on the lower side, the molten glass produced by S1 is produced while flowing on a cooled metal roller. That is, molten glass is poured between the rotating metal rollers cooled by water and rapidly cooled to produce glass fragments of about 3 to 5 mm.

S3 system is coarsely crushed (powder 2 to 3mm) and crushed (~50μm). This is to coarsely pulverize glass fragments of 3 to 5 mm after S2 is rapidly cooled to form a powder of 2 to 3 mm, and further pulverize it to a powder of about 50 μm.

S4 system is finely pulverized (2 to 3 μm) (jet milling device). This is to use a jet milling device to further pulverize the S3 ~50μm powder into a powder (glass powder, glass frit) about 2 to 3μm.

S5 is a glass frit used to complete the sintering aid for aluminum electrodes of solar cells.

As above, the raw materials are raised to a predetermined temperature (900°C to 1200°C) and dissolved to produce molten glass, and the molten glass is rapidly cooled to produce glass fragments (3 to 5 mm), which are coarsely crushed, crushed, and finely crushed And produce glass frit (glass powder) of about 2 to 3 μm (refer to Fig. 6).

Fig. 2 shows an example of manufacturing samples of the ABS glass of the present invention.

(A) of Figure 2 shows sample No. 1, sample No. 2, and sample No. 3. These are the names given to the samples.

的原料所構成。其它試樣亦由圖示的原料所構成。 Figure 2(b) shows the molar% of the raw material of each sample. For example, sample No.1 is

Of raw materials. Other samples are also composed of the raw materials shown.

In addition, the "range" at the right end shows the range of raw materials that can produce a good glass frit, and a good glass frit can be produced in the following range shown in the figure.

Figure 2 (c) shows the blending ratio (g). This is an example of g when each raw material is blended at the molar% ratio shown in Figure 2(b).

Figure 2 (d) shows an example of the characteristics of the glass frit of the present invention.

‧It can be observed that even if the molten glass flows out onto the metal plate, it does not crystallize.

‧It can be observed that none of the samples No.2 and No.3 are crystallized.

‧Observation of softening: When the glass frit manufactured in Figure 1 is added to the crucible and the temperature rises,

‧Sample No.1 starts to melt on the surface at 570℃ and completely melts at 595℃.

‧Either sample No.2 and No.3 series starts to melt at 572°C and completely melts at 587°C.

Figure 2 (e) shows an example of the glass transition temperature. For each transition temperature as shown in the figure, the value shown in the figure can be obtained for each.

Here, it is clear that the crystal melting temperature of Sample Nos. 1, 2, and 3 is 515°C, 525°C, and 524°C, and any one of them is 600°C or less, and the target 650°C or less can be achieved.

Fig. 3 shows an example of the glass frit (component molar ratio) for aluminum paste for solar cells of the present invention. This is for easy understanding, and the molar% part of the sample Nos. 1, 2, and 3 in the second figures (a) and (b) of the aforementioned experimental example was taken out and arranged.

‧Vanadium V ₂ O ₅ of sample No.1 is 77.58 mol% and is in the range of 55 to 80 mol%. Barium BaO is 22.22 mol% and is in the range of 15 to 30 mol%.

‧Sample No.2 and No.3 are also within the range as shown in the figure.

For the above sample Nos. 1, 2, and 3, the various characteristics described in Figure 2 (d) and (e) can be observed and measured. In particular, the melting temperature can be reached below 650°C. It is clear that it can be used for mixing Glass frit for aluminum paste in solar cells. Moreover, this glass frit does not contain iron, copper, nickel, or chromium, and does not degrade the characteristics of the solar cell even if it is used for a long period of time.

Fig. 4 is an explanatory diagram showing an example of the upper and lower limit of the range of each component of the ABS glass of the present invention.

Figure 4(a) shows an example of the upper and lower limits of vanadium V ₂ O ₅ (55 to 80 mol%).

‧When vanadium V ₂ O ₅ is below the lower limit (55 mol%), no glass skeleton is formed.

‧When vanadium V ₂ O ₅ is above the upper limit (80 mol%), it is difficult to adjust the mechanical strength. Water resistance deteriorates.

Fig. 4(b) shows an example of the upper and lower limits of barium BaO (actually, BaCO ₃ is added as a raw material, and CO ₂ is released to become BaO during heating and dissolution).

‧When barium BaO (BaCO ₃ ) is below the lower limit (15 mol%), homogeneous vitrification becomes difficult.

‧When barium BaO (BaCO ₃ ) is higher than the upper limit (30 mol%), the mechanical strength deteriorates.

Figure 4(c) shows the description of other additives (for example, the three types of additives in Figure 4(d)).

‧The following additives will not prevent aluminum materials (trivalent) from forming P-type functions on silicon (tetravalent), or assume additional tasks. Depending on the situation, there may be no additives.

Figure 4(d) shows an example of additives.

‧Aluminum Al ₂ O ₃ (0 to 10 mol%): ‧Boron B ₂ O ₃ (0 to 7 mol%): ‧Silicon SiO ₂ (0 to 7 mol%): ‧The blending ratio of the 3 components It is important to have a good balance. Otherwise, the uniformity cannot be maintained and crystals will precipitate. It may be any two components or one component or none. However, in order to maintain water resistance, it is better to add silicon SiO ₂ .

Fig. 5 is an explanatory diagram showing the glass frit for firing aluminum electrodes for solar cells of the present invention. When aluminum paste is coated and sintered on the back of a solar cell to form an aluminum electrode, this is a problem (requirement) (1), (2), (3), and the present invention that are considered necessary for the glass frit mixed with the aluminum paste The form made by the means of solution.

Figure 5(a) shows the problem "(1) Lower melting point" and the solution of the present invention. In the present invention, as mentioned above, it is realized that vanadium and barium are the main components, and the temperature is below 600°C. This is because the sintering temperature is determined by the midpoint between the melting point of aluminum (660°C) and the melting point of the glass frit. Therefore, in the present invention, the melting point of the glass frit is specified to be 650°C or less, and in the experiment can achieve 600°C or less ( The crystal dissolution temperature in Fig. 2(e) is 515°C, 525°C, and 524°C, and can achieve 600°C or less).

Figure 5(b) shows the problem "(2) Composition affecting the life of silicon solar cells" and the solution of the present invention. In the present invention, as mentioned above, no iron, copper, nickel, chromium, etc. are contained. It is basically a combination of vanadium, barium, silicon, aluminum, and boron. Here, silicon, aluminum, and boron are contact materials for back aluminum.

As mentioned above, under long-term harsh use conditions of solar cells, glass frit is made of materials that do not contain iron, copper, nickel, chromium, etc., which will cause adverse effects, so such adverse effects can be avoided.

Figure 5(c) shows the problem "(3) The silicon substrate does not warp during sintering" and the solution of the present invention. In the present invention, as described above, the constituent components of vanadium and barium prevent the substrate from warping during aluminum sintering.

Fig. 6 shows an overview photograph of the ABS glass of the present invention. This is an overview photograph showing the ABS glass manufactured by the steps in Figure 1 above.

Figure 6(a) shows a photographic example of ABS glass. This is an example of an overview photograph when the glass fragments of S2 (called ABS glass) in the aforementioned Figure 1 were subjected to a trial experiment.

Figure 6 (b) shows an overview photograph of coarsely broken (2 to 3 mm) ABS glass. The ABS glass system is crushed into glass pieces of about 2 to 3 mm.

Figure 6(c) shows an overview photograph of crushed (~50μm) ABS glass. The ABS glass system is crushed to ~50μm. In addition, it is finely pulverized into about 2 to 3 μm in the jet milling device to complete the glass frit.

In addition, in the manufacture of aluminum paste mixed with glass frit, for example, by sequentially mixing (1) aluminum fine powder, (2) glass frit (fine powder) of the present invention, (3) organic material, and (4) organic solvent , (5) Resin (or the order can also be changed), add it to the container and fully stir to manufacture.

Then, in order to form a required aluminum pattern on the back surface of the solar cell substrate with the manufactured aluminum paste, screen printing, solvent dissipation, and sintering are performed to form aluminum electrodes.

Fig. 7 shows the manufacturing flow chart (Part 2) of the ABS glass (Art Beam solar cell glass) of the present invention.

In Fig. 7, the S11 system prepares and melts glass raw materials (900°C to 1200°C) (after the electric furnace temperature rises, it is added and left for 1 hour). In this system, when the temperature of the electric furnace rises to the optimal temperature determined by the experiment in the range of 900°C to 1200°C, the prepared glass material is inserted into the crucible, dissolved, and left for 1 hour. In addition, the raw material put in the crucible may be melted by raising the temperature to a predetermined temperature in an electric furnace and left for 1 hour. In the experiment, the glass raw materials are, for example, the following shown in Fig. 8 and Fig. 9 described later.

(單位為莫耳%)

(Unit is mole%)

S12 is the manufacturing of glass fragments (3 to 5mm). As described on the lower side, this is manufactured while circulating the molten glass manufactured by S11 on a cooled metal roller. That is, molten glass is poured between the rotating metal rollers cooled by water and rapidly cooled to produce glass fragments of about 3 to 5 mm.

S13 system is used for coarse crushing (powder 2 to 3mm) and crushing (~50μm). This is to coarsely pulverize glass fragments of 3 to 5 mm after S12 rapid cooling to form a powder of 2 to 3 mm, which is further pulverized to a powder of about 50 μm.

S14 system is finely pulverized (2 to 3 μm) (jet milling device). This is to use a jet milling device to further pulverize the S13 ~50μm powder into a powder (glass powder, glass frit) about 2 to 3μm.

S15 is a glass frit used to complete the sintering aid for aluminum electrodes of solar cells.

As above, the raw materials are raised to a predetermined temperature (900°C to 1200°C) and dissolved to produce molten glass, and the molten glass is rapidly cooled to produce glass fragments (3 to 5 mm), which are coarsely crushed, crushed, and finely crushed And produce glass frit (glass powder) of about 2 to 3 μm.

Fig. 8 shows an example of manufacturing samples of the ABS glass of the present invention (Part 2).

In Fig. 8, "Sample 11" in (a) represents sample 11. These lines indicate the names given to the sample 11, and the lower row indicates the names of raw materials (materials).

的原料所構成。 In Figure 8, the "molar ratio%" in the "molar ratio% (range)" in (b) represents the molar percentage of the sample material. For example, sample 11 is composed of

Of raw materials.

In addition, the "range" in the "mole ratio% (range" in Fig. 8(b)) shows the range of raw materials that can produce good glass frit. The following range in the figure shows that it can produce good glass frit .

In Figure 8, (c) represents mass (g). This is an example of g when each raw material is blended at the molar% ratio shown in Figure 8(b).

In Fig. 8, (d) shows an example of the characteristics of the glass frit of the present invention.

‧The state of the crucible is good. This means that the state when the above-mentioned raw materials are put into a crucible and melted is good.

‧The surface of the outflow state is "quite turbid", which means that the surface of the melt is "quite turbid" in the state after the melted material is quickly discharged from the crucible to the cooling device.

‧The so-called softening observation is "500℃: the pellets are round. 600℃: the pellets are stuck together", which means that when the glass material manufactured in Figure 7 is put into a crucible and the temperature rises, the pellets are 500℃ At 600℃, the particles are sticky and melted.

‧The so-called state after cooling means that the surface is "brown. It peels off from the crucible until it rises to 650℃", which means that the surface of the molten material is "brown" after cooling and the molten material put in the crucible rises to The molten material easily peels off from the crucible at 650°C.

In Fig. 8, the DTA in (e) is difficult to show sharp peaks in DTA measurement (measurement of transition point, softening point, crystallization, crystal melting, etc.).

Fig. 9 shows an example of the glass frit for aluminum paste for solar cells of the present invention (component molar ratio) (Part 2). This is for easy understanding, and the molar% part of sample 11 in Fig. 8 of the aforementioned experimental example and other samples 12 and 13 not shown in the figure are taken out and arranged, and the results (adhesion, I/V Characteristics).

Here, when aluminum Al ₂ O ₃ is added, it is easy to vitrify.

In addition, the phosphorus P ₂ O ₅ system is difficult to vitrify even if it is added in this state. Therefore, phosphorus is added as a compound of alkaline earth metal (for example, calcium) before it is melted in the molten material of the main material (the main skeleton composed of barium V ₂ O ₅ and vanadium BaO) and can be vitrified. For example, calcium dihydrogen phosphate (or calcium phosphate) hydrate (Ca(H ₂ PO ₄ ) ₂ ‧H ₂ O) is added.

For the above samples 11, 12, and 13, the various characteristics described in Figure 8 (d) and (e) can be observed and measured. In particular, the melting temperature can be reached below 650°C, and the sample 11 is evaluated in The adhesion described in the result column (an example of the solar cell substrate is the adhesion after the aluminum paste of the solar cell using glass frit is applied, dried, and sintered on the back), and the I/V characteristics of the solar cell are also Better results (for example, good and about 2 times or more) can be obtained than before. Moreover, this glass frit does not contain iron, copper, nickel, or chromium, and does not degrade the characteristics of the solar cell even if it is used for a long period of time.

Fig. 10 is an explanatory diagram showing an example of the upper and lower limits of the range of each component of the ABS glass of the present invention (No. 2).

Figure 10(a) shows an example of the upper and lower limits of vanadium V ₂ O ₅ (10 to 55 mol%).

‧When vanadium V ₂ O ₅ is below the lower limit (10 mol%), no glass skeleton is formed.

‧When vanadium V ₂ O ₅ is above the upper limit (55 mol%), it is difficult to adjust the mechanical strength. Water resistance deteriorates.

Here, the range of vanadium V ₂ O ₅ (10 to 55 mol%) is greatly reduced from Figure 4 (55 to 80 mol%) because of the addition of phosphorus P ₂ O ₅ (5 to 20 mol%) %) and CaO (5 to 20 mol%), etc., so the addition rate of vanadium V ₂ O ₅ , which is the most main material, decreases.

Figure 10(b) shows an example of the upper and lower limits of barium BaO (actually, BaCO ₃ is added as a raw material, and CO ₂ is released when heated to dissolve to become BaO).

‧When barium BaO (BaCO ₃ ) is below the lower limit (10 mol%), homogeneous vitrification becomes difficult.

‧When barium BaO (BaCO ₃ ) is above the upper limit (40 mol%), the mechanical strength will deteriorate.

Figure 10(c) shows an explanation of other additives (for example, the two types of additives in Figure 10(d)).

‧It will not prevent aluminum materials (trivalent) from forming P-type functions on silicon (quaternary), or undertake additional tasks. Depending on the situation, there may be no additives.

Figure 10(d) shows an example of additives.

‧Aluminum Al ₂ O ₃ (1 to 10 mol%): ‧Boron B ₂ O ₃ (5 to 20 mol%): ‧It is important that the blending ratio of the two components has a good balance. Otherwise, the uniformity cannot be maintained and the crystals will precipitate without vitrification.

Figure 10(e) shows an example of addition of phosphorus P ₂ O ₅ (5 to 20 mol%) and calcium CaO (5 to 20 mol%). Phosphorus P ₂ O ₅ (5 to 20 mol%) and calcium CaO (5 to 20 mol%) are added, and tricalcium phosphate Ca ₃ (PO ₄ ) _{2 is added} .

‧Because the phosphorus system reacts with water, it is better to add phosphoric acid.

‧Because compounds containing alkali metals deteriorate the characteristics of solar cells, phosphorus compounds with alkaline earth metals (such as calcium) are added.

‧When adding boron (trivalent), phosphorus (5-valent) and antimony (5-valent) compounds, compared with the addition of two types of boron and phosphorus, the addition of three types at the same time is in I /V characteristics and adhesion are poor.

In addition, as the above-mentioned phosphorus compound with alkaline earth metals (for example, calcium), the experiment was carried out by adding tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or calcium metaphosphate Ca(PO ₃ ) _2, and good results were obtained with either . In particular, the use of the former tricalcium phosphate Ca ₃ (PO ₄ ) ₂ as a food additive can be obtained inexpensively, and compared with the latter, the number of oxygen O is 8 (the number of the latter is 6) In terms of, good results can be obtained. In addition, when manufacturing the glass frit of the present invention, carbon C (including compound) may be attached or mixed into the raw material in a small amount, because the oxygen O oxidizes the small amount of carbon C to produce gas (carbon dioxide). CO ₂ etc.) can also be released, so it must contain some oxygen O.

Moreover, when phosphoric acid P ₂ O ₅ and calcium CaO are directly added, it is impossible to produce a good glass frit. Similarly, substances other than alkaline earth metals added as calcium CaO, such as sodium, potassium, etc., are degraded and cannot be used when solar cells are exposed to strong sunlight for a long period of time (for example, more than 10 years).

Fig. 11 is an explanatory diagram showing the glass frit for firing aluminum electrodes for solar cells of the present invention (Part 2). When the aluminum paste is coated and sintered on the back of the solar cell to form the aluminum electrode, this is a problem deemed necessary for the glass frit mixed with the aluminum paste (requirement) (1), (2), (3), (4) And the table created by the solution of the present invention.

Figure 11(a) shows the problem "(1) Lower melting point" and the solution of the present invention. In the present invention, as mentioned above, it is realized that vanadium and barium are the main components, and the temperature is below 600°C. This is because the sintering temperature is determined by the midpoint between the melting point of aluminum (660°C) and the melting point of the glass frit. Therefore, in the present invention, the melting point of the glass frit is specified to be 650°C or less, and in the experiment, it can achieve 600°C or less

Fig. 11(b) shows the problem "(2) Composition affecting the life of silicon solar cell" and the solution of the present invention. In the present invention, as mentioned above, no iron, copper, nickel, chromium, etc. are contained. It is basically a combination of vanadium, barium, silicon, aluminum, boron, phosphorus, calcium, and zinc. Here, aluminum and boron are contact materials for back aluminum.

As mentioned above, under long-term severe use of solar cells, glass frit is made of materials that do not contain iron, copper, nickel, chromium, etc. that will cause adverse effects, so such adverse effects can be avoided.

Figure 11(c) shows the problem "(3) The silicon substrate does not warp during sintering" and the solution of the present invention. In the present invention, as described above, the constituent components of vanadium and barium prevent the substrate from warping during aluminum sintering.

Figure 11(d) shows the problem "(4) Adhesion, I/V improvement" and the solution of the present invention. In the present invention, as described above, by adding constituent components such as phosphorus and calcium, the adhesion of aluminum to the substrate during sintering becomes good and the I/V characteristics can also be improved.

Next, using FIGS. 12 to 14 to describe in detail the following steps: in FIGS. 1 to 11, the glass frit of the present invention is added as an auxiliary agent to produce aluminum paste; and The prepared aluminum paste is coated on the back of the solar cell and sintered to form an aluminum electrode step.

Figure 12 is an explanatory diagram showing the aluminum paste of the present invention. This is an example of the constituent components of the aluminum paste, for example, as shown below. These components are mixed to produce an aluminum paste (see Fig. 13).

(1) Aluminum powder:

‧Purity: 99.7% or more

‧Average particle size: 1-20μm

‧Shape: spherical, elliptical

(2) The vanadate glass (glass frit) of the present invention:

‧Particle size: 1 to 3μm

‧The weight ratio of the whole aluminum paste is 0.1 to 1%

(3) Other glass powder:

‧Particle size: 1 to 3μm

The weight ratio of the whole aluminum paste is 0 to 1%

(4) Resin:

‧The weight ratio of the whole aluminum paste is 0.1 to 3%

‧Ethyl cellulose, nitrocellulose, etc.

(5) Solvent:

‧The weight ratio of the whole aluminum paste is about 25% (suitable for clay for screen printing, etc.)

‧Diethylene glycol, monobutyl ether, etc.

Fig. 13 shows the manufacturing flow chart of the aluminum paste of the present invention.

In Figure 13, S21 uses a mixer to blend solvent and resin (organic vehicle). This is to prepare the organic medium by putting the solvent and the resin (4) in Fig. 12 (5) into the mixer and mixing them thoroughly.

S22 is to blend glass into organic medium. This is to put the organic medium produced in S21, the vanadate glass powder (glass frit) of the present invention in Figure 12 (2), and other glass powders as necessary (3) into the mixer and mix them thoroughly.

S23 is blended with aluminum powder. This is the step of further blending the aluminum powder of Figure 12 (1). With respect to 100 parts by weight of the aluminum powder of Figure 12 (1), the organic medium is used to make 1.5 to 100 parts by weight (preferably 30 to 50 parts by weight) of the aluminum powder of (1).

S24 series finished aluminum paste.

In accordance with the procedures from S21 to S24 above, combine the solvent, (4) resin, (2) the vanadate glass powder (glass frit) of the present invention and (3) other glass powders as necessary, and then (1) The aluminum powder is mixed thoroughly using a mixer in order to produce aluminum paste.

Figure 14 is a flow chart showing the calcination of the aluminum paste of the present invention. This is an example of a calcining flow chart when the aluminum paste prepared in Figure 13 is coated, dried, and calcined on the back of the solar cell to form an aluminum electrode.

In Figure 14, S31 is coated on the back and silicon surface of the solar cell. For example, it is coated with a thickness of 5 to 13 mg/cm ² . This is coated on the object that forms the aluminum electrode, such as the back of a solar cell, or directly coated on the silicon surface on the back of a silicon substrate.

S32 system is dried. This is to put the aluminum paste applied in S31, for example, in a drying oven at 100 to 300°C for 1 minute to 10 minutes to dissipate the solvent and dry. Also, it can be dried by sending hot air.

The S33 series performs aluminum sintering. For example, it is placed in a sintering furnace at about 500 to 900°C (1200°C if necessary) for sintering for 1 to 300 seconds, and the aluminum electrode is formed on the back surface or silicon surface of the solar cell. In addition, an infrared lamp may be used to directly irradiate infrared rays for sintering. During the sintering, the vanadate glass of the present invention, especially the additive, is firmly fixed to the back of the solar cell or the silicon surface, and at the same time, it is also firmly fixed to the aluminum powder. It can be confirmed that the previous glass powder cannot be used. Achieve strong fixation. That is, when the lead wire is welded to an aluminum electrode formed by sintering, even if the lead wire is stretched, it will not be easily peeled off as before, and it has been experimentally confirmed that the fixing strength is several times higher than before.

S34 is completed by cooling at room temperature. This is after aluminum sintering in S33 and cooling at room temperature to complete the formation of aluminum electrodes on the back of the solar cell and the silicon surface.

As above, the aluminum paste added with the vanadate glass powder of the present invention as an auxiliary agent is applied on the back or silicon surface of the solar cell (S31), dried (S32), and then calcined (S33) , And it is possible to form an aluminum electrode on the back of the solar cell or on the silicon surface with a fixed strength several times higher than before.

Claims (20)

A glass frit that is mixed into a conductive paste that is coated and sintered on a substrate to form a conductive electrode. The glass frit is: 55 to 80 mol% of vanadium V ₂ O ₅ and 15 to 30 mol% As the main material that does not contain alkali metal, the aluminum Al ₂ O ₃ of 0 to 10 mol%, the boron B ₂ O ₃ of 0 to 7 mol%, and the silicon SiO _{2 of} 0 to 7 mol% One or more of the above-mentioned main materials are mixed as additives, and the mixed main materials and additives that do not contain iron, copper, nickel, or chromium are heated to produce molten glass, and the molten glass is rapidly cooled to form The glass frit will melt below 650℃. The glass frit described in item 1 of the scope of patent application, wherein aluminum paste is used as the aforementioned conductive paste. The glass frit described in the first item of the patent application, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. The glass frit described in the second item of the patent application, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. An aluminum paste containing the glass frit described in any one of items 1 to 4 in the scope of the patent application as an auxiliary agent. A glass frit that is to be mixed into a conductive paste that is coated and sintered on a substrate to form a conductive electrode. The glass frit is: 10 to 55 mol% of vanadium V ₂ O ₅ and 10 to 40 mol% Barium BaO as a main material that does not contain alkali metals, is obtained by mixing additives into the aforementioned main materials, and these mixed main materials and additives that do not contain iron, copper, nickel, or chromium are heated to produce molten glass, and It is manufactured by pulverizing the fragments formed by rapid cooling of the molten glass. The glass frit is melted at 650°C or lower. The aforementioned additives are aluminum Al ₂ O ₃ and 1 to 20 mole% of aluminum. Mole% boron B ₂ O ₃ , or 5 to 20 mole% phosphorus P ₂ O ₅ and 5 to 20 mole% calcium CaO, and does not contain more than one kind of alkali metal. The glass frit according to the sixth item of the scope of patent application, wherein the calcium CaO added together with the phosphorus P ₂ O ₅ belonging to the aforementioned additive is set as a compound with one or more of phosphorus and alkaline earth metals. The glass frit described in item 7 of the scope of patent application, wherein the calcium CaO added together with the phosphorus P ₂ O ₅ belonging to the aforementioned additives is designed to be a compound with one or more types of phosphorus and alkaline earth metals The tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or calcium metaphosphate Ca(PO ₃ ) ₂ . The glass frit described in item 6 of the scope of patent application, wherein aluminum paste is used as the aforementioned conductive paste. The glass frit described in item 7 of the scope of patent application, wherein aluminum paste is used as the aforementioned conductive paste. The glass frit described in item 8 of the scope of patent application, wherein aluminum paste is used as the aforementioned conductive paste. The glass frit described in claim 6, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. The glass frit described in item 7 of the scope of patent application, wherein the aforementioned The plate coating and sintering to form a conductive electrode is to coat and sinter the solar cell substrate to form a conductive aluminum electrode. The glass frit described in claim 8, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. The glass frit described in claim 9, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is coating and sintering on the substrate of a solar cell to form a conductive aluminum electrode. The glass frit described in claim 10, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. The glass frit described in claim 11, wherein the aforementioned coating and sintering on the substrate to form a conductive electrode is to coat and sinter the substrate of a solar cell to form a conductive aluminum electrode. An aluminum paste is added with the glass frit described in any one of items 6 to 17 in the scope of the patent application as an auxiliary agent. A method for manufacturing glass frit, which is a method for manufacturing glass frit that is mixed into a conductive paste that is coated and sintered on a substrate to form a conductive electrode. The method is characterized by using 55 to 80 mole% of vanadium V ₂ O ₅ and 15 to 30 mol% of barium BaO is used as the main material that does not contain alkali metals, and 0 to 10 mol% of aluminum Al ₂ O ₃ , 0 to 7 mol% of boron B ₂ O ₃ , and 0 to 7 mol% Ear% silicon SiO ₂ is mixed into the aforementioned main material as an additive, and the mixed main material and the additive do not contain iron, copper, nickel, or chromium. The molten glass is produced by heating The molten glass is rapidly cooled to generate fragments, and the generated fragments are crushed to produce a glass frit that will melt below 650°C. A method for manufacturing glass frit, which is a method for manufacturing a glass frit that is mixed into a conductive paste that is coated and sintered on a substrate to form a conductive electrode. The method is characterized in that: 10 to 55 mol% of vanadium V ₂ O ₅ and 10 to 40 mol% of barium BaO is used as the main material that does not contain alkali metals, and the additives are mixed into the aforementioned main materials, and the mixed main materials and additives that do not contain iron, copper, nickel, or chromium are heated The molten glass is produced, wherein the aforementioned additives are 1 to 10 mol% aluminum Al ₂ O ₃ and 1 to 20 mol% boron B ₂ O ₃ , or 5 to 20 mol% phosphorus P ₂ O ₅ and 5 to 20 mol% of calcium CaO, and one or more of the ones that do not contain alkali metals, the resulting molten glass is rapidly cooled to generate fragments, and the resulting fragments are crushed to produce them that will melt below 650°C Frit glass.

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