JP5713273B2 - Joining material and member joining method using the same - Google Patents

Description

  The present invention relates to a bonding material suitable for bonding constituent members in a product such as a semiconductor light emitting device.

  In recent years, semiconductor light-emitting element devices such as white LEDs are expected to be applied to lighting applications as next-generation light sources that replace incandescent bulbs and fluorescent lamps. In general, a white LED has a structure in which a mixture of an inorganic phosphor powder and a resin is coated and molded on an LED chip that is an excitation light source. However, since heat and light emitted from the LED chip are intensively applied to a limited portion, a resin having poor heat resistance is easily colored or deformed. For this reason, there is a problem that a change in emission color occurs in a short period of time, and the lifetime as a semiconductor light emitting element device is shortened. Such a problem is considered to be serious as the output of the LED chip is increased, and development of a semiconductor light emitting element device having excellent heat resistance has been desired.

  On the other hand, a semiconductor light-emitting element device using a wavelength conversion member made only of an inorganic material that does not use a resin has been proposed (see, for example, Patent Document 1). Since the resin having poor heat resistance is not used for the wavelength conversion member and is made of only an inorganic material, the wavelength conversion member has excellent heat resistance and hardly undergoes thermal degradation.

  For example, in the case of a flip-chip type semiconductor light emitting device, the wavelength conversion member is directly bonded onto the semiconductor light emitting device substrate using a bonding material made of a resin such as silicone resin. If a resin such as a silicone resin is used, bonding can be performed at a relatively low temperature, so that components such as a wavelength conversion member and a semiconductor light emitting element are not thermally deformed during bonding.

JP 2003-258308 A

  When the wavelength conversion member and the semiconductor light emitting element substrate are bonded using a resin, the resin is discolored by heat generated from the semiconductor light emitting element, and the transmittance of the excitation light decreases with time, and the light flux value is likely to decrease. Become. Moreover, there is a possibility that destruction such as peeling may occur due to the alteration of the resin due to heat.

  Accordingly, an object of the present invention is to provide a bonding material capable of manufacturing a product such as a semiconductor light emitting device excellent in heat resistance and weather resistance.

  As a result of intensive studies, the present inventors have solved the above problem by using a specific member having excellent heat resistance and weather resistance instead of the resin used for joining the structural members in the product such as the semiconductor light emitting device. It has been found that the problem can be solved, and is proposed as the present invention.

  That is, the present invention relates to a bonding material comprising a glass film having a softening point of 500 ° C. or lower.

  As described above, for example, in a semiconductor light emitting element device, when the semiconductor light emitting element and the wavelength conversion member are bonded with resin, there is a problem that the resin is discolored by heat or light generated from the semiconductor light emitting element. On the other hand, since the bonding material of the present invention is made of a glass film that is an inorganic material, discoloration due to heat generated from the semiconductor light emitting element can be prevented. As a result, it is possible to prevent a decrease in luminous flux value over time.

  By the way, joining by a glass film is performed by installing a glass film between several to-be-joined members, and heating to the softening point vicinity of a glass film in the state which applied the pressure from the outside as needed. As described above, since the bonding with the glass film is performed at a higher temperature than the bonding using the resin, the characteristics of the bonded member itself such as the wavelength conversion member or the semiconductor light emitting element are deteriorated or thermally deformed. There is a risk. Since the bonding material of the present invention uses a glass film having a softening point as low as 500 ° C. or lower, low-temperature bonding is possible regardless of the glass material, and characteristic deterioration and thermal deformation of the bonded members are difficult to occur during bonding.

  Note that when glass frit, sol-gel glass, or the like is used as the bonding material, there are problems that it is difficult to uniformly adjust the thickness of the bonding layer or that bubbles are likely to be generated after heat treatment. For example, in a semiconductor light-emitting device, if the thickness of the bonding layer between the semiconductor light-emitting device and the wavelength conversion member is not uniform, the emission color tends to vary, and if bubbles exist in the bonding layer, light scattering may occur, resulting in luminous efficiency. Tends to decrease. Since glass frit is usually used in a paste form, a pasting process and a debinding process are required, and the manufacturing process becomes complicated.

  On the other hand, when a glass film is used as the bonding material, it is easy to make the thickness of the bonding layer uniform, and bubbles are not easily generated. In particular, it is easy to reduce the thickness of the bonding layer (for example, 200 μm or less) by appropriately selecting the thickness of the glass film. Also, the manufacturing process is very simple.

  Moreover, if the joining member of this invention is used, joining strength is high compared with the conventional resin bonding agent, and the problem of peeling of to-be-joined members can be improved significantly.

  Secondly, the bonding material of the present invention is characterized in that the glass film has a thickness of 200 μm or less.

  By making the thickness of the glass film as very thin as 200 μm or less, light absorption inside the bonding material can be suppressed. Therefore, for example, in a semiconductor light emitting element device, light absorption loss can be reduced, and luminous efficiency can be improved. In addition, even if the linear thermal expansion coefficient difference between the bonding material and each member to be bonded is large, the generated stress is small, so that breakage such as peeling hardly occurs.

  Thirdly, the bonding material of the present invention is characterized in that the glass film is made of tin phosphate glass.

  Tin phosphate glass is suitable as the bonding material of the present invention because it tends to lower the softening point.

Fourth, in the bonding material of the present invention, the tin phosphate glass contains, as a composition, mol%, SnO 35 to 80%, P ₂ O ₅ 5 to 40%, and B ₂ O ₃ 1 to 30%. It is characterized by.

  When the tin phosphate glass has the above composition, a bonding material having a low softening point and excellent weather resistance can be obtained.

  Fifth, the present invention relates to a method for joining members, characterized in that any one of the above-mentioned joining materials is installed between the members to be joined and heat-joined at a temperature lower than the softening point of the joining material.

It is a schematic diagram of a flip chip type semiconductor light emitting device using the bonding material of the present invention.

  The glass film used for the bonding material of the present invention is not particularly limited as long as it has a softening point of 500 ° C. or lower, preferably 450 ° C. or lower. For example, tin phosphate glass or zinc borate glass is used. Is possible. In particular, tin phosphate glass is preferred because it tends to lower the softening point.

The Suzurin glasses, in mole percent _{composition, SnO 35~80%, P 2 O} 5 5~40%, it is preferable that contain 2 O 3 1~30% _B. The reason for limiting the glass composition as described above is as follows.

  SnO is a component that forms a glass skeleton and lowers the softening point. The SnO content is preferably 35 to 80%, 40 to 70%, 50 to 70%, particularly 55 to 65%. When the content of SnO decreases, the softening point increases and low temperature bonding tends to be difficult. On the other hand, when the content of SnO increases, devitrification bumps resulting from Sn precipitate in the glass, and the transmittance tends to decrease. Moreover, it becomes difficult to vitrify.

P ₂ O ₅ is a component that forms a glass skeleton. The content of P ₂ O ₅ is preferably 5 to 40%, 10 to 30%, particularly preferably 15 to 24%. When the content of P ₂ O ₅ is reduced, it is difficult to vitrify. On the other hand, when the content of P ₂ O ₅ is increased, the softening point is increased and low temperature bonding tends to be difficult. Further, the weather resistance tends to be remarkably lowered.

It is preferable the value of SnO _/ P 2 _{O 5} is 0.9～16,1.5～16,1.5～10 molar ratio, in particular in the range of 2-5. If the value of SnO / P ₂ O ₅ is smaller than 0.9, the softening point tends to increase and low temperature bonding tends to be difficult. Further, the weather resistance tends to be remarkably lowered. On the other hand, when the value of SnO / P ₂ O ₅ is larger than 16, devitrification particles due to Sn are precipitated in the glass, and the transmittance of the glass tends to be lowered.

B ₂ O ₃ is a component that improves weather resistance. It is also a component that stabilizes the glass. The content of B ₂ O ₃ is preferably 1 to 30%, 2 to 20%, particularly 4 to 18%. When the content of B ₂ O ₃ is reduced, the above effect is hardly obtained. On the other hand, when the content of B ₂ O ₃ increases, the weather resistance tends to decrease. Moreover, there is a tendency that the softening point increases and low-temperature bonding becomes difficult.

  In addition to the above components, the following components can be added.

Al ₂ O ₃ is a component that stabilizes the glass. The content of Al ₂ O ₃ is preferably 0 to 10%, 0 to 7%, particularly preferably 1 to 5%. When the content of Al ₂ O ₃ increases, the softening point tends to increase and low temperature bonding tends to be difficult.

SiO ₂ is a component that stabilizes the glass in the same manner as Al ₂ O ₃ . The content of SiO ₂ is preferably 0 to 10%, 0 to 7%, particularly preferably 0.1 to 5%. When the content of SiO ₂ increases, the softening point tends to increase and low temperature bonding tends to be difficult. Moreover, it becomes easy to phase-separate glass.

Li ₂ O is a component that significantly lowers the softening point. The content of Li ₂ O is preferably 0 to 10%, 0 to 7%, particularly 1 to 5%. When the content of Li ₂ O increases, the glass becomes extremely unstable and becomes difficult to vitrify.

Na ₂ O is a component that lowers the softening point of glass. The content of Na ₂ O is preferably 0 to 10%, 0 to 7%, particularly preferably 0.1 to 5%. When the content of Na ₂ O increases, the glass becomes unstable and becomes difficult to vitrify.

K ₂ O is a component that slightly lowers the softening point of the glass. The content of K ₂ O is preferably 0 to 10%, 0 to 7%, particularly 1 to 5%. When the content of K ₂ O increases, the glass becomes unstable and becomes difficult to vitrify.

_{Incidentally, Li 2 O, Na 2 O} , K 2 O is 0 to 10% in total 0 to 7%, particularly preferably 1-5%. If the total amount of these components exceeds 10%, the glass becomes unstable and it is difficult to vitrify.

  MgO, CaO, and SrO are components that stabilize glass and facilitate vitrification. The content of these components is preferably 0 to 10%, 0 to 7%, particularly 1 to 5%, respectively. When the content of each component is larger than the above range, devitrification is likely to occur, causing a decrease in transmittance.

  BaO is also a component that stabilizes glass and facilitates vitrification. The content of BaO is preferably 0 to 5%, 0 to 3%, particularly preferably 0.1 to 1%. When the content of BaO is increased, the glass is extremely devitrified and tends to cause a decrease in transmittance.

  In addition, MgO, CaO, SrO, and BaO are preferably 0 to 10%, 0 to 7%, particularly 1 to 5% in total. If the total amount of these components exceeds 10%, devitrification may occur and cause a decrease in transmittance.

In addition to the above components, various components can be added as long as the gist of the present invention is not impaired. For example, in order to improve the weather resistance, ZnO, Ta ₂ O ₅ , TiO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , La ₂ O ₃ may be added up to 10% in total.

However, since coloring components such as Fe ₂ O ₃ , Cr ₂ O ₃ , CoO, CuO, and NiO color the glass and reduce the internal transmittance of the glass, these components are combined in an amount of 0.02% or less. It is preferable to suppress to.

  The thickness of the glass film is preferably 200 μm or less, 100 μm or less, and particularly preferably 50 μm or less. When the thickness of the glass film exceeds 200 μm, light absorption inside the bonding material increases. For example, when used for joining constituent members of a semiconductor light emitting element device, it causes a decrease in luminous efficiency. In addition, when the difference in coefficient of linear thermal expansion between the bonding material and each member to be bonded is large, the generated stress increases and breakage such as peeling tends to occur. On the other hand, if the glass film is too thin, it is easy to break and difficult to handle, so the lower limit is preferably 1 μm or more, particularly 5 μm or more.

  The bonding material of the present invention is obtained by a method of stretching a substantially rectangular base glass made of the above material while heating under a predetermined condition, or a method of forming a molten glass of the above material by an overflow down draw method or a slot down draw method. Can be produced.

  The bonding temperature when the members are bonded using the bonding material of the present invention is preferably lower than the softening point of the bonding material. Specifically, the difference between the softening point of the bonding material and the bonding temperature (the softening point of the bonding material−the bonding temperature) is preferably over 0 ° C., more preferably 5 ° C. or more, and particularly preferably 10 ° C. or more. When the bonding temperature is equal to or higher than the softening point of the bonding material, the bonding material flows during bonding and bubbles and voids are likely to be generated, and the thickness of the bonding layer is likely to be uneven. On the other hand, when the bonding temperature is too low as compared with the softening point of the bonding material, the softening state of the bonding material becomes insufficient and the bonding tends to be difficult. Therefore, the difference between the softening point of the bonding material and the bonding temperature is preferably 35 ° C. or lower, particularly 30 ° C. or lower.

  Note that the softening point of the bonding material of the present invention is preferably lower than the softening point of the member to be bonded, whereby the softening deformation of the member to be bonded at the time of bonding can be suppressed. Specifically, the softening point of the joining material is preferably 50 ° C. or more, particularly 100 ° C. or less, lower than the softening point of the member to be joined.

The smaller the difference in coefficient of linear thermal expansion between the bonding material and each member to be bonded, the more the heat generated during bonding and the heat generated during use of the resulting product (for example, the heat generated by the semiconductor light emitting element in the semiconductor light emitting element device). The stress generated between materials is small, and breakage such as peeling is unlikely to occur. Specifically, the difference in coefficient of linear thermal expansion between the joining member and each joined member is preferably 50 × 10 ⁻⁷ or less, particularly preferably 30 × 10 ⁻⁷ or less.

  Further, the smaller the refractive index nd difference between the bonding material and each member to be bonded, the more the light scattering loss at each material interface can be suppressed. Thereby, for example, when the bonding material of the present invention is applied to a semiconductor light emitting device, the light emission efficiency can be improved. Therefore, the refractive index nd difference between the bonding member and each member to be bonded is preferably 0.5 or less, particularly 0.3 or less.

  Next, as an example of the embodiment of the bonding material of the present invention, a flip-chip type semiconductor light emitting device using the bonding material of the present invention will be described with reference to the schematic diagram of FIG.

  The semiconductor light emitting device 1 has a structure in which a semiconductor light emitting device 3 is bonded to a base 7 by bonding 8 and a wavelength conversion member 2 is bonded to the upper portion of the semiconductor light emitting device 3 through a bonding material 6. Yes. Here, the semiconductor light emitting element 3 is formed of a substrate 4 and a semiconductor layer 5 formed on the substrate 4. The substrate 4 is a base material by the bonding material 6 and the semiconductor layer 5 is bonded by the bonding 8. 7 respectively.

  The semiconductor light-emitting element device 1 joins the wavelength conversion member 2 and the substrate 4 by performing a heat treatment in a state where, for example, the wavelength conversion member 2 and the substrate 4 in the semiconductor light-emitting element 3 are installed via the bonding material 6, Thereafter, the semiconductor layer 5 and the substrate 7 in the semiconductor light emitting element 3 can be manufactured by bonding them by bonding 8. Here, the bonding material 6 is placed between the wavelength conversion member 2 and the semiconductor light emitting element 3, and the heat treatment is performed with pressure applied from the outside, so that the bonding state becomes strong.

  Bonding of the substrate 4 and the wavelength conversion member 2 may be performed before the semiconductor layer 5 is formed by performing an epitaxial growth process on the substrate 4 or after the semiconductor layer 5 is formed on the substrate 4. Good. Further, the wavelength conversion member 2 and the substrate 4 may be bonded after the semiconductor light emitting element 3 and the substrate 7 are bonded together by bonding 8.

  In addition, if foreign matter exists between the wavelength conversion member 2 and the bonding material 6 or between the bonding material 6 and the substrate 4, bubbles and voids are generated, and therefore, the heat treatment is preferably performed in a clean room of class 1000 or less.

  2. Description of the Related Art A semiconductor light emitting device (flip chip type) in which a wavelength conversion member is bonded to the substrate side of a semiconductor light emitting device is adopted for a high power LED or the like. Heat treatment is performed at 300 to 350 ° C. for electrode bonding at the time of flip chip type mounting, and heating at the time of mounting by bonding the semiconductor light emitting element and the wavelength conversion member with a bonding material made of a glass film that is an inorganic material. No discoloration or deformation occurs due to processing. Moreover, since the softening point of the glass film is 500 ° C. or lower, low-temperature bonding is possible, and problems such as deterioration or deformation of the characteristics of the semiconductor light-emitting element and the wavelength conversion member are unlikely to occur during bonding.

  In addition, as a wavelength conversion member, since it is excellent in heat resistance, it is preferable that an inorganic fluorescent substance powder is disperse | distributed in a glass matrix. Specific examples include those made of a sintered powder of a mixed powder containing inorganic phosphor powder and glass powder, and phosphor-containing crystallized glass.

  Any inorganic phosphor powder can be used as long as it is generally available in the market. Inorganic phosphor powders include oxides such as YAG, nitrides, oxynitrides, sulfides, rare earth oxysulfides, halides, aluminate chlorides, halophosphates, and the like.

  A plurality of inorganic phosphor powders may be mixed and used in accordance with the wavelength range of excitation light or light emission. For example, when white light is obtained by irradiation with ultraviolet excitation light, inorganic phosphor powders that emit fluorescence such as blue, green, yellow, and red may be mixed and used.

  The glass powder has a role as a medium for stably holding the inorganic phosphor powder. Moreover, since the color tone of the wavelength conversion member varies depending on the glass composition of the glass powder and the reactivity with the inorganic phosphor powder varies, it is preferable to select the glass composition to be used in consideration of these conditions. Furthermore, it is also important to determine the addition amount of the inorganic phosphor powder suitable for the glass composition and the thickness of the wavelength conversion member.

Examples of the glass powder include SiO ₂ —B ₂ O ₃ —RO-based glass (R represents Mg, Ca, Sr, Ba), and SiO ₂ —B ₂ O ₃ —R ′ ₂ O-based glass (R ′ represents Li, Na, and K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —ZnO glass, ZnO—B ₂ O ₃ glass, SnO—P ₂ O ₅ type glass can be used. What is necessary is just to select these glasses suitably according to the characteristic made into the objective. For example, when firing at a low temperature, a ZnO—B ₂ O ₃ system glass or SnO—P ₂ O ₅ system glass having a relatively low softening point may be selected, and when it is desired to improve the weather resistance of the wavelength conversion member, SiO ₂ —B ₂ O ₃ —RO glass, SiO ₂ —B ₂ O ₃ —R ′ ₂ O glass, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ — A ZnO-based glass may be selected.

The average particle diameter D50 of the glass powder is preferably from 0.1 to 100 μm, particularly preferably from 1 to ₅₀ μm. When the average particle diameter D ₅₀ of the glass powder is too small, the greater the amount of generation of bubbles during the firing. If many bubbles are contained in the wavelength conversion member, light emission is likely to be caused and light emission efficiency tends to be reduced. The preferred porosity is 2% or less, particularly 1% or less. On the other hand, when the average particle diameter D ₅₀ is too large, the inorganic phosphor powder is less likely to be uniformly dispersed in the wavelength conversion member, as a result, variation tends to occur in the emission color of the wavelength conversion member.

  The luminous efficiency (lm / W) of the wavelength conversion member varies depending on the type and content of the inorganic phosphor powder dispersed in the glass matrix and the thickness of the luminescent color conversion member. If you want to increase the luminous efficiency of the wavelength conversion member, adjust the thickness by reducing the thickness to increase the transmittance of excitation light or fluorescence, or increase the content of inorganic phosphor powder to increase the amount of light to be converted. That's fine. However, when the content of the inorganic phosphor powder is too large, it is difficult to obtain a dense structure and the porosity tends to increase. In addition, it is necessary to reduce the thickness in order to obtain white light. As a result, problems such as it becomes difficult for the excitation light to be efficiently applied to the inorganic phosphor powder, and the mechanical strength of the wavelength conversion member tends to decrease. On the other hand, when there is too little content of inorganic fluorescent substance powder, it becomes difficult to obtain sufficient light emission. Therefore, the content of the inorganic phosphor powder in the wavelength conversion member is preferably 0.01% to 30%, 0.05% to 20%, and particularly preferably 0.08% to 15% in mass%.

Al ₂ O ₃ (sapphire) is generally used as the substrate of the semiconductor light emitting device, but other examples include Si (silicon), GaAs (gallium arsenide), and SiC (silicon carbide).

  The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

  Table 1 shows examples and comparative examples when the bonding material of the present invention is applied to the manufacture of a semiconductor light emitting device.

First, the wavelength conversion member was produced as follows. SiO ₂ -B ₂ O ₃ to prepare a raw material powder so that -RO based glass composition was vitrified by melting 1 hour at 900-1400 ° C. in a platinum crucible. The molten glass was formed into a film, and the obtained film was pulverized with a ball mill and then passed through a 325-mesh sieve to classify the glass powder (softening point 850 ° C., refractive index, average particle diameter D _50: 45 μm) nd 1.56).

  Next, YAG phosphor powder was mixed with glass powder, and pressure-molded using a mold to prepare a button-shaped preform having a diameter of 1 cm. The preform was fired at 800 ° C. to obtain a sintered body. The sintered body was rough-polished and processed to have a diameter of 8 mm and a thickness of 0.2 mm. Subsequently, double-sided mirror polishing was performed using a surface plate having a cloth material woven with diamond abrasive grains and fibers on the surface to obtain a wavelength conversion member.

  A single crystal sapphire substrate (refractive index nd 1.76), a bonding material, and a wavelength conversion member are stacked in this order on an alumina setter that has been cleaned in advance and bonded by heat treatment in a clean oven. went. In addition, the single crystal sapphire substrate, the bonding material, and the wavelength conversion member used those that had been precision cleaned with pure water in advance. The heat treatment was performed by raising the temperature up to 250 ° C. at 20 ° C./min, holding at 380 ° C. for 30 minutes, and then naturally cooling to room temperature.

The bonding materials were tin phosphate glass plates for Examples 1 and 2 (glass composition (mol%): SnO 62%, P ₂ O ₅ 21%, B ₂ O ₃ 11%, MgO 3%, Al ₂ O ₃ 3%), for Comparative Example 1, a glass film produced by heating and stretching a silicate glass plate at a predetermined temperature was used. In Comparative Example 2, two-component silicone resin was mixed at a specified ratio, applied between the single crystal sapphire substrate and the wavelength conversion member, adhered, and cured by curing at 120 ° C. for 1 hour. The softening point of the glass film was measured using a macro-type differential thermal analysis (DTA) apparatus for the glass powder obtained by pulverizing the glass film.

  In this example, a simulated semiconductor light-emitting device was fabricated by combining a blue LED with the single crystal sapphire substrate and wavelength conversion member obtained as described above, and the light emission efficiency was measured.

  The joined body was reheated at 350 ° C. for 10 minutes assuming the temperature required for electrode joining during flip chip mounting, and the luminous efficiency was measured in the same manner. A hot plate was used for heating.

  The luminous efficiency was evaluated as follows. On the blue LED, the above-mentioned joined body is placed so that the single crystal sapphire substrate is in contact with the blue LED light emitting surface, the blue LED is turned on in the calibrated integrating sphere, and the light emitted through the joined body is compact spectroscope. The emission spectrum was obtained on a PC through a CCD. From the obtained spectrum, the total luminous flux value (lm) was calculated from analysis software (OP-Wave manufactured by Ocean Photonics), and the luminous efficiency was calculated by dividing by the power (W) applied to the blue LED.

  As is clear from Table 1, in Examples 1 and 2, the single crystal sapphire substrate and the wavelength conversion member can be bonded at low temperature, and after heat treatment at 350 ° C. assuming electrode bonding during flip-chip mounting. It can be seen that the decrease in luminous efficiency is small and the heat resistance is excellent.

  On the other hand, in Comparative Example 1, the softening point of the bonding material was high, and low-temperature bonding at 500 ° C. or lower was not possible. Further, in Comparative Example 2, it can be seen that the light emission efficiency is remarkably lowered after the heat treatment at 350 ° C.

  In this example, the example in which the bonding material of the present invention was applied to the manufacture of a semiconductor light emitting device was shown. However, the present invention is not limited to this application, and various members that require low temperature bonding of members are required. It can be applied for use.

  The bonding material of the present invention can be used, for example, for bonding a semiconductor light emitting element and a wavelength conversion member in a flip chip type semiconductor element light emitting device, as well as a sealing material between substrates of devices such as organic EL lighting, solar cells, and organic EL displays. It is also suitable.

DESCRIPTION OF SYMBOLS 1 Semiconductor light-emitting device 2 Wavelength conversion member 3 Semiconductor light-emitting device 4 Substrate 5 Semiconductor layer 6 Joining material (glass film)
7 Substrate 8 Bonding

Claims (6)

Ri Do from the glass film having a softening point 500 ° C. or less, bonding material characterized Rukoto be used to heat joining of the workpieces in the form of the glass film.   2. The method according to claim 1, wherein the glass is produced by a method of stretching a substantially rectangular base glass while heating it under a predetermined condition, or a method of forming a molten glass by an overflow down draw method or a slot down draw method. Bonding material.   The bonding material according to claim 1, wherein the glass film has a thickness of 200 μm or less.   The bonding material according to claim 1, wherein the glass film is made of tin phosphate glass. Suzurin glasses are in mole percent composition, SnO 35 to _80%, joining according to claim 4, characterized in that it contains _{P 2 O 5 5~40%, B} 2 O 3 1~30% material.   6. A member joining method, wherein the joining material according to claim 1 is installed between members to be joined and heat-joined at a temperature lower than a softening point of the joining material.