JP2011230973A - Bismuth-based non-lead glass and composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide bismuth-based non-lead glass and a composite material using it, preventing the over-coat layer from eroding due to plating, allowing calcination at a temperature below 800°C, and achieving excellent cost performance.SOLUTION: The bismuth-based non-lead glass does not practically contain PbO, and in terms of mass percent it contains 20-48% of BiO, 6-27% of BO, 10-30% of SiO, 5-20% of AlO, 0-20% of MgO+CaO+SrO+BaO, 0-less than 7% of ZnO, and 0-10% of LiO+NaP+KO, where AlO/BiOis 0.33-0.73.

Description

  The present invention relates to a bismuth-based lead-free glass suitable for uses such as an overcoat for electronic circuits and a composite material using the same.

  Conventionally, glass has been used as an overcoat material for protecting and insulating electronic circuit electrodes and resistors.

  In forming an overcoat layer in an electronic circuit, a method of firing at a temperature of 800 ° C. or lower is employed in order to prevent reaction with the electrode and the resistor and to suppress deterioration of the characteristics of the electrode and the resistor. . Therefore, an overcoat material for an electronic circuit is required to be able to be fired at a temperature of 800 ° C. or lower and not to react with an electrode or a resistor.

PbO—B ₂ O ₃ —SiO ₂ based lead glass powder as shown in Patent Document 1 has been used to satisfy the above required characteristics, but in recent years, environmental protection has been increased and the use of environmentally hazardous substances has been reduced. From this movement, Bi ₂ O ₃ —ZnO—B ₂ O ₃ based lead-free glass powders as shown in Patent Documents 2 and 3 have been proposed.

JP 58-64245 A JP 2002-308645 A JP 2007-63105 A

  By the way, these electronic circuits are subjected to a plating process in which an overcoated electronic circuit is immersed in a plating solution in order to impart various characteristics such as anticorrosion, optical characteristics, mechanical characteristics, and electrical characteristics depending on applications. Applied. Usually, since this plating solution is an acidic solution, the glass used for the overcoat material is required to have excellent acid resistance.

  However, since the glass disclosed in Patent Document 2 has low acid resistance, there is a problem that the overcoat layer is eroded by the plating solution, and the characteristics such as the insulation of the electronic circuit are deteriorated.

Moreover, since the glass disclosed in Patent Document 3 contains 55% by mass or more of expensive Bi ₂ O ₃ , there is a problem that the manufacturing cost increases.

  An object of the present invention is to provide a bismuth-based lead-free glass and a composite material using the same that are resistant to erosion of the overcoat layer by plating and can be fired at a temperature of 800 ° C. or less, and are excellent in cost performance. is there.

As a result of various experiments, the inventor of the present invention contains SiO ₂ and Al ₂ O ₃ in a bismuth-based lead-free glass, and the value of Al ₂ O ₃ / Bi ₂ O ₃ is 0.33 or more in terms of mass ratio. Thus, it is found that the acid resistance of the glass can be improved, and is proposed as the present invention.

That is, the bismuth-based lead-free glass of the present invention does not substantially contain PbO, and is in mass percentage, Bi ₂ O ₃ 20 to 48%, B ₂ O ₃ 6 to 27%, SiO ₂ 10 to 30%, Al _{2 O 3 5~20%, MgO +} CaO + SrO + BaO 0~20%, ZnO less than _{0~7%, Li 2 O + Na} 2 O + K 2 O 0~10%, with _{Al 2 O 3 / Bi 2 O} 3 0.33~0.73 It is characterized by being.

  Moreover, the composite material of the present invention is characterized by containing glass powder made of the above-mentioned bismuth-based non-lead glass.

The bismuth-based lead-free glass of the present invention has a low softening point, a wide vitrification range capable of obtaining a dense fired film in which crystals do not easily precipitate during firing, and excellent acid resistance. Therefore, a dense overcoat layer can be obtained at a temperature of 800 ° C. or less, and even if the electronic circuit is plated, the overcoat layer is hardly eroded, and protection and insulation of the electrodes of the electronic circuit can be maintained. Further, since the suppressed content of expensive Bi ₂ O _3, it can be manufactured at low cost. Therefore, it is suitable as a bismuth-based lead-free glass for electronic circuit overcoat and a composite material using the same.

  Even if the glass of the present invention does not contain PbO, the melting point can be lowered relatively easily, and the basic composition is a bismuth-based lead-free glass that easily expands the vitrification range.

In general, bismuth-based lead-free glass tends to have lower acid resistance than lead-based glass, but in the present invention, 10% by mass or more of SiO ₂ which is a component that improves the acid resistance of glass is contained. . Further, in order to prevent the destabilization glass by the addition of SiO _2, with the inclusion of Al ₂ O ₃ is a component for stabilizing the glass to expand the vitrification range of 5 wt%, Al ₂ O The value of ₃ / Bi ₂ O ₃ is strictly limited so that the mass ratio is 0.33 or more. Therefore, it is possible to obtain a glass having a wide vitrification range and an excellent acid resistance capable of obtaining a dense fired film in which crystals do not easily precipitate during firing, and the bismuth-based lead-free glass of the present invention is used in an electronic circuit. Even when used as an overcoat material, the overcoat layer is hardly eroded in the plating process, and the protection and insulation of the electrodes of the electronic circuit can be maintained.

  The reason for limiting the glass composition as described above in the present invention is as follows.

Bi ₂ O ₃ is a component that lowers the softening point of glass, and its content is 20 to 48%. When the content of Bi ₂ O ₃ is reduced, the softening point of the glass is increased and it is difficult to fire at a temperature of 800 ° C. or lower. On the other hand, when the content increases, the material cost increases. A preferable range of Bi ₂ O ₃ is 20 to 47%, and a more preferable range is 20 to 45%.

B ₂ O ₃ is a component that forms a glass skeleton and widens the vitrification range and stabilizes the glass, and its content is 6 to 27%. When the content of B ₂ O ₃ decreases, crystals tend to precipitate during firing, and a dense overcoat layer tends to be difficult to obtain. In the plating process, the overcoat layer tends to be eroded and the electrodes of electronic circuits, etc. It becomes difficult to maintain protection and insulation. On the other hand, when the content increases, the softening point of the glass rises and it becomes difficult to fire at a temperature of 800 ° C. or lower. A preferable range of B ₂ O ₃ is 7 to 26%, and a more preferable range is 7 to 25%.

SiO ₂ is a component that forms a glass skeleton and improves the acid resistance of the glass, and its content is 10 to 30%. When the content of SiO ₂ decreases, the acid resistance of the glass tends to decrease, and the overcoat layer is easily eroded in the plating process, making it difficult to maintain protection and insulation of the electrodes of the electronic circuit. On the other hand, when the content increases, the softening point of the glass rises and it becomes difficult to fire at a temperature of 800 ° C. or lower. In addition, glass tends to be unstable, crystals tend to precipitate during firing, and it becomes difficult to obtain a dense overcoat layer. In the plating process, the overcoat layer is easily eroded and maintains the protection and insulation of the electrodes of electronic circuits. It becomes difficult to do. A preferable range of SiO ₂ is 13 to 29%, and a more preferable range is 15 to 27%.

Al ₂ O ₃ is a component that widens the vitrification range and stabilizes the glass and improves the acid resistance of the glass, and its content is 5 to 20%. When the content of Al ₂ O ₃ decreases, it becomes difficult to obtain the effect of stabilizing the glass, crystals tend to precipitate during firing, and it becomes difficult to obtain a dense overcoat layer, and the acid resistance of the glass tends to decrease. In the plating process, the overcoat layer is easily eroded and it is difficult to maintain protection and insulation of the electrodes of the electronic circuit. On the other hand, when the content increases, the softening point of the glass rises and it becomes difficult to fire at a temperature of 800 ° C. or lower. A preferable range of Al ₂ O ₃ is 7 to 19%, and a more preferable range is 8 to 18%.

In order to stabilize the glass while suppressing an increase in the softening point and to suppress the precipitation of crystals during firing to obtain a dense fired film, the value of Al ₂ O ₃ / Bi ₂ O ₃ is expressed by mass ratio. It is important that the range is 0.33 to 0.73. If the value of Al ₂ O ₃ / Bi ₂ O ₃ becomes too small, it becomes difficult to obtain an effect of stabilizing the glass, crystals are likely to precipitate during firing, and it becomes difficult to obtain a dense overcoat layer. In the plating process, the overcoat layer is easily eroded and it is difficult to maintain protection and insulation of the electrodes of the electronic circuit. On the other hand, when the value of Al ₂ O ₃ / Bi ₂ O ₃ becomes too large, the softening point of the glass increases and it becomes difficult to fire at a temperature of 800 ° C. or lower. A preferable range of Al ₂ O ₃ / Bi ₂ O ₃ is 0.33 to 0.70%, and a more preferable range is 0.35 to 0.68%.

  The alkaline earth metal oxides of MgO, CaO, SrO and BaO are components that lower the softening point of the glass and adjust the thermal expansion coefficient, and the total content thereof is 0 to 20%. When the total amount of these components increases, crystals tend to precipitate during firing, and it tends to be difficult to obtain a dense overcoat layer.In the plating process, the overcoat layer is easily eroded, protecting the electrodes of electronic circuits and the like. It becomes difficult to maintain insulation. A preferable range of MgO + CaO + SrO + BaO is 0 to 15%, and a more preferable range is 0 to 12%. The content of each component of these alkaline earth metal oxides is preferably 0 to 6%.

  ZnO is a component that lowers the softening point of the glass, but since it is a component that significantly reduces the acid resistance of the glass, its content is 0 to 7%. When the ZnO content is increased, the acid resistance of the glass is remarkably lowered, and the overcoat layer is eroded in the plating process, making it difficult to maintain protection and insulation of the electrodes of the electronic circuit. The preferable range of ZnO is 0 to 6%, and the more preferable range is 0 to 5%.

The alkali metal oxides of Li ₂ O, Na ₂ O, and K ₂ O are components that lower the softening point of the glass and adjust the thermal expansion coefficient, and the content is 0 to 10% in total. . When the total amount of these components increases, the overcoat layer, the electrode and the resistor are likely to react during firing, and the characteristics of the electronic circuit may be deteriorated. In addition, crystals tend to precipitate during firing, and a dense overcoat layer tends to be difficult to obtain. In the plating process, the overcoat layer is easily eroded and it is difficult to maintain protection and insulation of the electrodes of the electronic circuit. A more preferable range of Li ₂ O + Na ₂ O + K ₂ O is 0 to 8%. A more preferable range is 0 to 6%. In addition, as for content of each component of these alkali metal oxides, it is desirable that it is 0 to 4%, respectively.

Moreover, the bismuth-type non-lead glass of this invention can add a various component in the range which does not impair the required characteristic besides the said component. For example, in order to lower the softening point of the glass, the total amount of Cs ₂ O, Rb ₂ O, etc. is up to 5%, and in order to stabilize the glass and improve water resistance and acid resistance, ZrO ₂ , Y Add ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ₅ , SnO ₂ , TiO ₂ , Nb ₂ O ₅ , P ₂ O ₅ , CuO, CeO ₂ , V ₂ O _5, etc. to a total amount of 10%. Can do.

  PbO is a component that lowers the melting point of glass, but it is also an environmentally hazardous substance, so substantial introduction should be avoided.

  In the present invention, “substantially not introduce” refers to a level that is not actively used as a raw material and mixed as an impurity, and specifically means that the content is 0.1% or less. .

  The glass having the above composition is stable and hardly crystallized at a temperature of 800 ° C. or lower. Moreover, it is excellent in acid resistance and has a softening point of 800 ° C. or lower.

  In order to obtain the composite material of the present invention using the above bismuth-based non-lead glass, the above-mentioned bismuth-based non-lead glass can be obtained by pulverizing, classifying, and processing into a powder form. Further, ceramic powder may be added to the glass powder in order to improve the strength and acid resistance or adjust the thermal expansion coefficient.

Incidentally, the particle size of the glass powder has an average particle diameter _{D 50} of 3.0μm or less, the maximum particle diameter _{D max} may be desirable to use those 20μm or less. This is because if either of these exceeds the upper limit, large bubbles are likely to remain in the fired film.

  Moreover, when mixing ceramic powder, the mixing amount is glass powder 50-100 mass% (more preferably 55-95 mass%), ceramic powder 0-50 mass% (more preferably 5-45 mass%). It is preferable. This is because when the amount of ceramic powder increases, the proportion of the glass powder becomes relatively low and it tends to be difficult to obtain a dense overcoat layer. This is because it is difficult to maintain protection and insulation of the electrodes and the like.

  Various materials can be used as the ceramic powder. For example, alumina, zircon, zirconia, mullite, silica, cordierite, titania, tin oxide, various inorganic pigments, etc. can be used alone or in combination. .

  Next, a method for using the composite material of the present invention will be described. The composite material of the present invention can be used in the form of a paste, for example.

  When used in the form of a paste, a thermoplastic resin, a plasticizer, a solvent and the like are used together with the composite material described above. In addition, as a ratio of the composite material which occupies for the whole paste, about 30-90 mass% is common.

  The thermoplastic resin is a component that increases the film strength after drying and imparts flexibility, and the content is generally about 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used, and these are used alone or in combination.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film, and the content thereof is generally about 0 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate and the like can be used, and these are used alone or in combination.

  The solvent is a material for pasting the material, and its content is generally about 10 to 30% by mass. As the solvent, for example, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate or the like can be used alone or in combination.

  The paste can be prepared by preparing the above composite material, thermoplastic resin, plasticizer, solvent and the like and kneading them at a predetermined ratio.

  In order to form an overcoat layer on an electronic circuit using such a paste, first, these pastes are applied to the electronic circuit on which electrodes or the like are formed by using a screen printing method or a batch coating method. After forming a coating layer having a predetermined thickness, it is dried. Then, a predetermined overcoat layer can be obtained by holding and baking at a temperature of 400 to 800 ° C. for 5 to 20 minutes. If the firing temperature is too low or the holding time is shortened, sufficient sintering cannot be performed, and it becomes difficult to form a dense film. On the other hand, if the firing temperature is too high or the holding time is long, the overcoat layer, the electrode and the resistor tend to react during firing, and the characteristics of the electronic circuit are likely to deteriorate.

  In the above description, a method using a paste is described as an example of a method for forming the overcoat layer, but the composite material of the present invention is not limited to these methods, and the green sheet method is used. It is a material that can be applied to other forming methods such as a photosensitive paste method and a photosensitive green sheet method.

  Hereinafter, 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, respectively.

  Each sample in the table was prepared as follows.

First, the raw materials were prepared so as to have the glass composition shown in Table by mass%, and mixed uniformly. Subsequently, after putting in a platinum crucible and melting at 1400 ° C. for 2 hours, the molten glass was formed into a thin plate shape. Subsequently, they were pulverized in a ball mill, an air classifier to a mean particle diameter D ₅₀ 3.0μm or less, the maximum particle diameter D _max to obtain a sample of the following glass powder 20 [mu] m. The softening point of each glass powder sample thus obtained was evaluated.

  Next, the above glass powder sample was mixed with a terpineol solution containing 5% ethyl cellulose, kneaded with a three-roll mill to form a paste, and then the paste was made into alumina so that a fired film of about 20 μm was obtained. It was applied onto the substrate by a screen printing method, dried, held in an electric furnace at the temperature of the softening point for 10 minutes and baked to obtain an overcoat layer. Using each sample thus obtained, the presence or absence of crystal precipitation and the acid resistance were evaluated.

  As can be seen from the table, the sample No. In Nos. 1 to 7, the glass had a softening point of 756 ° C. or lower and could be sufficiently fired at a temperature of 800 ° C. or lower. Further, no crystals were precipitated during firing, and a highly dense fired film could be obtained. Furthermore, the weight loss in the acid resistance evaluation was as small as 0.6% or less, and the acid resistance was excellent.

  On the other hand, sample No. which is a comparative example. No. 8 had a large weight loss of 3.7% in the acid resistance evaluation and low acid resistance. Sample No. In No. 9, crystals precipitated during firing, a dense fired film could not be obtained, the weight loss in the acid resistance evaluation was as large as 2.2%, and the acid resistance was low. Furthermore, sample no. No. 10 has a high softening point of 842 ° C., and it is expected that the electrodes and the resistor easily react during firing, and the characteristics of the electronic circuit deteriorate.

  In addition, about the softening point of glass, it measured using the macro-type differential thermal analyzer, and made the softening point the value of the 4th inflection point.

  Regarding the presence or absence of crystal precipitation, the presence or absence of crystal precipitation was evaluated using an optical microscope for the overcoat layer obtained as described above. In the table, “◯” indicates that no crystal precipitation was observed, and “X” indicates that crystal precipitation was observed.

  The acid resistance was evaluated by immersing the overcoat layer obtained as described above in a sulfuric acid stock solution at 25 ° C. for 1 minute, washing with water, drying, measuring the weight loss, and determining the ratio. In addition, it means that acid resistance is so low that this value is large.

  The bismuth-based lead-free glass and composite material of the present invention are not limited to electronic circuit overcoat applications, and can be used, for example, as glass and composite materials for applications such as binders for electronic component materials and sealing materials. It is.

Claims (4)

Substantially free of PbO, by mass percentage, Bi ₂ O ₃ 20-48%, B ₂ O ₃ 6-27%, SiO ₂ 10-30%, Al ₂ O ₃ 5-20%, MgO + CaO + SrO + BaO 0-20 %, ZnO 0 to less than 7%, Li ₂ O + Na ₂ O + K ₂ O 0 to 10%, Al ₂ O ₃ / Bi ₂ O ₃ 0.33 to 0.73.   A composite material comprising the glass powder comprising the bismuth-based lead-free glass according to claim 1.   The composite material according to claim 2, further comprising ceramic powder.   The composite material according to claim 2 or 3, comprising 50 to 100% by mass of bismuth-based non-lead glass and 0 to 50% by mass of ceramic powder.