JP2018184314A - Silver phosphate-based glass composition and sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver phosphate-based glass composition that can be sealed at low temperature without containing environmentally harmful lead and halogen, and a sealing material using the same.SOLUTION: A silver phosphate-based glass composition contains, by mol%, 20 or more and less than 40% of AgO, 20-35% of PO, 0-10% of NbO, 15-40% of TeOand more than 5 to less than 20% of ZnO.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a silver phosphate glass that can be hermetically sealed at a low temperature of 400 ° C. or less without containing harmful lead and halogen, and a sealing material using the same.

  Sealing materials are used for semiconductor integrated circuits, crystal resonators, flat display devices, LD glass terminals, and the like.

  Since the above-mentioned sealing material requires chemical durability and heat resistance, a glass-based sealing material is used instead of a resin-based adhesive. Glass sealing materials are required to have properties such as mechanical strength, fluidity, and weather resistance, but the sealing temperature should be as low as possible for sealing electronic components that are sensitive to heat. Is required. Specifically, sealing at 400 ° C. or lower is required. Therefore, as a glass that satisfies the above characteristics, lead borate glass containing a large amount of PbO that has an extremely large effect of lowering the melting point has been widely used (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. Sho 63-315536 JP-A-6-24797 Japanese Patent No. 4573204

In recent years, environmental problems have been pointed out with respect to PbO contained in lead borate glass, and it is desired to replace lead borate glass with glass containing no PbO. Therefore, various low melting glass has been developed as a substitute for lead borate glass. Among them, Bi ₂ O ₃ —B ₂ O ₃ glass described in Patent Document 2 is expected as an alternative candidate for lead borate glass, but its sealing temperature is as high as 450 ° C. or higher, and sealing is performed at a lower temperature. It cannot be used for applications that require stopping.

Patent Document 3 discloses AgI-Ag ₂ O-based glass as a glass that can be sealed at a low temperature of 400 ° C. or lower. However, halogen has also been pointed out as an environmental problem, and does not contain halogen. Is desired.

In view of the above, an object of the present invention is to provide a silver phosphate glass composition that can be sealed at a low temperature without containing environmentally harmful lead or halogen, and a sealing material using the same. To do.

Silver phosphate glass composition of the present invention, in _mol%, Ag 2 O less than _{20~40%, P 2 O 5 20~35} %, Nb 2 O 5 0~10%, TeO 2 15~40%, It contains more than ZnO 5 and less than 20%.

Since the silver phosphate glass composition of the present invention contains Ag ₂ O and ZnO as essential components, it has a low melting point and is excellent in water resistance. In general, when the melting point of the glass is lowered, vitrification does not occur, or milky whitening or phase separation occurs and it is difficult to obtain a homogeneous glass. However, it contains 20% or more of P ₂ O ₅ as an essential component. Therefore, the glass is stable and a homogeneous glass can be obtained.

  The silver phosphate glass composition of the present invention preferably contains substantially no PbO or halogen. Halogen includes halides as well as fluorine, chlorine, bromine and iodine. Halides are fluoride, chloride, bromide, and iodide. Here, “substantially free of PbO and halogen” in the present invention refers to the case where the PbO and halogen contents in the glass composition are each 1000 ppm or less.

  The sealing material of the present invention is characterized by containing 50 to 100% by volume of a glass powder made of the above silver phosphate glass composition and 0 to 50% by volume of a refractory filler powder.

  It is possible to provide a silver phosphate glass composition that can be sealed at a low temperature without containing lead or halogen harmful to the environment, and a sealing material using the same.

It is a schematic diagram which shows the measurement curve obtained by a macro type differential thermal analyzer.

Silver phosphate glass composition of the present invention, in _mol%, Ag 2 O less than _{20~40%, P 2 O 5 20~35} %, Nb 2 O 5 0~10%, TeO 2 15~40%, ZnO more than 5 to less than 20%. The reason for limiting the glass composition as described above is shown below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified.

Ag ₂ O is a main component for lowering the softening point and has the effect of increasing the water resistance of the glass because it is hardly soluble in water, and its content is 20 to less than 40%, preferably 25 to 35. %. When the content of Ag 2 _O is too small, the viscosity of the glass (softening point, etc.) becomes high, the water resistance tends to decrease with low temperature sealing is difficult. On the other hand, the glass when the content of Ag 2 _O is too large, thermally unstable, the glass is liable to devitrify upon melting or during sintering.

P ₂ O ₅ is a component for forming a glass network, the content is from 20 to 35%, preferably 21 to 33%, more preferably 22 to 30%. When the content of P ₂ O ₅ is too small, glass becomes thermally unstable, the glass is liable to devitrify upon melting or during sintering. On the other hand, when the content of P ₂ O ₅ is too large, the viscosity of the glass (softening point, etc.) becomes high, the water resistance tends to decrease with low temperature sealing is difficult.

Nb ₂ O ₅ stabilizes the glass thermally, and is effective in improving water resistance and fluidity. Its content is 0 to 10%, preferably 0 to 7%, more preferably 1 ~ 5%. When the content of Nb ₂ O ₅ has too large, high glass viscosity (softening point, etc.) it tends to be difficult to cold sealing.

TeO ₂ lowers the softening point and is effective for improving water resistance, and its content is 15 to 40%, preferably 20 to 35%. When the content of TeO ₂ is too small, the viscosity (softening point, etc.) of the glass becomes high, and it becomes difficult to seal at low temperature, and the water resistance tends to decrease. On the other hand, when the content of TeO ₂ is too large, glass becomes thermally unstable, the glass is liable to devitrify upon melting or during sintering. Moreover, fluidity tends to be lowered.

  ZnO has the effect of lowering the softening point, and its content is more than 5 to less than 20%, preferably 6 to 18%. When there is too little content of ZnO, the viscosity (softening point etc.) of glass will become high and low temperature sealing will become difficult easily. On the other hand, if the ZnO content is too large, the glass becomes thermally unstable, and the glass tends to devitrify during melting or firing.

  In addition to the above components, the silver phosphate glass composition of the present invention may contain the following components in the glass composition.

WO ₃ is a component that thermally stabilizes the glass and suppresses devitrification and is a component that increases water resistance, and its content is preferably 0 to 10%, more preferably 0 to 5%. It is. When the content of WO ₃ is too large, is impaired balance of components glass composition, glass becomes thermally unstable in reverse.

  BaO, SrO, and CaO are components that stabilize the glass thermally and increase water resistance, and their content is a total amount, preferably 0 to 5%. If the content is too large, the glass becomes thermally unstable, and the glass tends to devitrify during melting or firing. The contents of BaO, SrO, and CaO are each preferably 0 to 5%.

Li ₂ O, Na ₂ O, and K ₂ O have an effect of lowering the softening point, and their content is a total amount, preferably 0 to 5%. If the content is too large, the glass becomes thermally unstable, and the glass tends to devitrify during melting or firing, and the water resistance tends to decrease. The contents of Li ₂ O, Na ₂ O, and K ₂ O are each preferably 0 to 5%.

Ga ₂ O ₃ is a component that thermally stabilizes the glass and increases water resistance. However, since it is very expensive, its content is preferably less than 0.01%, more preferably not contained. preferable.

MnO ₂ , Fe ₂ O ₃ , NiO, and CuO are components that thermally stabilize the glass and suppress devitrification, and each can be added to less than 2%. If the content is too large, the glass becomes thermally unstable, and the glass tends to devitrify during melting or firing.

In addition to the above components, other components such as MgO, SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , and Bi ₂ O ₃ may be added up to 10% in total in the glass composition.

  The sealing material of the present invention may contain a refractory filler in order to improve the mechanical strength or adjust the thermal expansion coefficient in the glass powder made of the above silver phosphate glass composition. The mixing ratio is 50 to 100% by volume of glass powder and 0 to 50% by volume of refractory filler, more preferably 70 to 99% by volume of glass powder and 1 to 30% by volume of refractory filler, and 80 to 95 volume of glass powder. %, Refractory filler 5 to 20% by volume is more preferable. When there is too much content of a refractory filler, since the ratio of glass powder will decrease relatively, it will become difficult to ensure desired fluidity | liquidity.

The refractory filler is not particularly limited, and various materials can be selected, but those that do not easily react with the glass powder are preferable.

Specifically, as a refractory filler, NbZr (PO ₄ ) ₃ , Zr ₂ WO ₄ (PO ₄ ) ₂ , zirconium phosphate, zircon, zirconia, tin oxide, aluminum titanate, quartz, β-spodumene, mullite, Titania, quartz glass, β-eucryptite, β-quartz, willemite, cordierite, NaZr ₂ (PO ₄ ) ₃ type solid solution such as Sr _0.5 Zr ₂ (PO ₄ ) ₃ or the like alone or 2 A mixture of seeds or more can be used. The particle diameter of the refractory filler is preferably one having an average particle diameter D50 of about 0.2 to ₂₀ μm.

The softening point of the silver phosphate glass composition and the sealing material of the present invention is preferably 380 ° C. or lower, particularly 360 ° C. or lower. If the softening point is too high, the viscosity of the glass increases, and the firing temperature (especially the sealing temperature, etc.) increases, which may damage the device during firing. In addition, although the minimum of a softening point is not specifically limited, Actually, it is 180 degreeC or more. Here, the “softening point” refers to a value measured with a macro-type differential thermal analyzer using glass powder having an average particle diameter D ₅₀ of 0.5 to 20 μm as a measurement sample. As measurement conditions, measurement is started from room temperature, and the rate of temperature rise is 10 ° C./min. In addition, the softening point measured with the macro type | mold differential thermal analyzer shows the temperature (Ts) of the 4th bending point in the measurement curve shown in FIG.

  Next, an example of a method for producing a glass powder using the silver phosphate glass composition of the present invention and a method of using the silver phosphate glass composition of the present invention as a sealing material will be described.

First, the raw material powder prepared to have the above composition is melted at about 700 to 900 ° C. for about 1 to 2 hours until a homogeneous glass is obtained. Next, the molten glass is formed into a film or the like, and then pulverized and classified to produce a glass powder made of the silver phosphate glass composition of the present invention. Incidentally, it is preferable that the average particle diameter _{D 50} of the glass powder is about 2 to 20 [mu] m. If necessary, various refractory filler powders are added to the glass powder.

  Next, a glass paste is prepared by adding a vehicle to glass powder (or a mixed powder of glass powder and refractory filler powder) and kneading. The vehicle mainly includes an organic solvent and a resin, and the resin is added for the purpose of adjusting the viscosity of the paste. Moreover, surfactant, a thickener, etc. can also be added as needed.

The organic solvent preferably has a low boiling point (for example, a boiling point of 300 ° C. or lower) and a small amount of residue after baking, and does not alter the silver phosphate glass, and its content is 10 to 40% by mass. It is preferable that Examples of the organic solvent include propylene carbonate, toluene, N, N′-dimethylformamide (DMF), 1,3-dimethyl-2-imidazolidinone (DMI), dimethyl carbonate, butyl carbitol acetate (BCA), isoamyl acetate, It is preferable to use dimethyl sulfoxide, acetone, methyl ethyl ketone or the like. Further, it is more preferable to use a higher alcohol as the organic solvent. Since the higher alcohol itself has viscosity, it can be made into a paste without adding a resin to the vehicle. In addition, pentanediol and its derivatives, specifically diethylpentanediol (C ₉ H ₂₀ O ₂ ), are excellent in viscosity and can be used as a solvent.

  The resin preferably has a low decomposition temperature and a small amount of residue after firing, and it is difficult to alter the silver phosphate glass, and its content is preferably 0.1 to 20% by mass. As the resin, it is preferable to use nitrocellulose, polyethylene glycol derivative, polyethylene carbonate, acrylic acid ester (acrylic resin) or the like.

  Next, using a dispenser or a coating machine such as a screen printing machine, the paste is sealed at the first member made of metal, ceramic or glass and the second member made of metal, ceramic or glass. Apply, dry and heat-treat at 200-400 ° C. By this heat treatment, the glass powder softens and flows to seal the first and second members.

  The silver phosphate glass composition and sealing material of the present invention can be used for purposes such as coating and filling in addition to sealing. Moreover, it can also be used in forms other than paste, specifically in the state of powder, green sheets, tablets and the like.

The present invention will be described in detail based on examples. Tables 1 and 2 show Examples (Sample Nos. 1 to 7) and Comparative Examples (Sample Nos. 8 to 10) of the present invention.

First, after preparing glass batches such as various oxides and carbonates so as to have the glass composition shown in the table and preparing a glass batch, the glass batch was put in a platinum crucible, and 1 to 700-900 ° C. Melted for 2 hours. Next, a part of the molten glass was poured into a stainless steel mold as a sample for TMA (push bar type thermal expansion coefficient measurement), and the other molten glass was formed into a film shape with a water-cooled roller. In addition, the sample for TMA performed the predetermined slow cooling process (annealing) after shaping | molding. Finally, the film-like glass was pulverized by a ball mill and then passed through a sieve having an opening of 75 μm to obtain a glass powder having an average particle diameter D ₅₀ of about 10 μm.

  Then, No. which mixes a refractory filler. For the samples 1, 2, 4, 5, and 7, as shown in the table, the obtained glass powder and the refractory filler powder were mixed to obtain a mixed powder.

NbZr (PO ₄ ) ₃ (shown as NZP in the table) and Zr ₂ WO ₄ (PO ₄ ) ₂ (shown as ZWP in the table) were used as the refractory filler powder. The average particle diameter _{D 50} of the refractory filler powder was about 10 [mu] m.

  The obtained mixed powder was fired at 390 ° C. for 30 minutes to obtain a fired body. The obtained fired body was used as a sample for TMA.

  No. About the samples of 1-10, the glass transition point, the thermal expansion coefficient, the softening point, the fluidity, and the devitrification resistance were evaluated.

  The glass transition point and the thermal expansion coefficient (30 to 150 ° C.) were measured using a TMA apparatus for the TMA sample.

  The softening point was measured with a macro type differential thermal analyzer. The measurement atmosphere was air, the temperature rising rate was 10 ° C./min, and the measurement was started from room temperature.

  The fluidity was evaluated as follows. 1 g of the powder sample was put into a mold having a diameter of 10 mm, press-molded, and then fired on a stainless steel plate at 390 ° C. for 30 minutes. The sintered body was evaluated as “を” when the flow diameter was 9 mm or more, “◯” when it was less than 8.8 to 9 mm, and “X” when less than 8.8 mm.

  The devitrification resistance was evaluated as follows. The surface state of the fired body was observed using an optical microscope (magnification 100 times). The case where no crystal was observed on the surface of the fired body was evaluated as “◯”, and the case where crystal was observed on the surface of the fired body was evaluated as “x”.

As is apparent from Table 1, No. 1 as an example of the present invention. Samples 1 to 7 were excellent in fluidity and devitrification resistance. On the other hand, No. which is a comparative example. Since the sample No. 8 contains ZnO in excess, No. 8 Since the 10 samples are contained excessively Ag 2 _O, fluidity, and was inferior in devitrification resistance. No. Sample 9 was inferior in fluidity because the ZnO content was too small.

  The silver phosphate glass composition and the sealing material of the present invention are suitable for sealing semiconductor integrated circuits, crystal resonators, flat display devices, and LD glass terminals.

Claims (3)

It contains, in mol%, Ag ₂ O 20 to less than 40%, P ₂ O ₅ 20 to 35%, Nb ₂ O ₅ 0 to 10%, TeO ₂ 15 to 40%, ZnO 5 to less than 20%. A silver phosphate glass composition.   The silver phosphate glass composition according to claim 1, which contains substantially no PbO or halogen.   A sealing material comprising 50 to 100% by volume of a glass powder comprising the silver phosphate glass composition according to claim 1 and 0 to 50% by volume of a refractory filler powder. .