JP2012140259A - Method for producing sheath tube for sealing semiconductor and sheath tube for sealing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a sheath tube for sealing a semiconductor where a semiconductor element is sealed at a low temperature and which is excellent in acid resistance.SOLUTION: The method for producing the sheath tube for sealing the semiconductor is characterized by including a step to produce a glass tube with SiO-BO-RO-based lead-free glass having a corresponding temperature to a viscosity of 10dPa s of 650°C or below and a content of BOof 15.5 mol% or more and a step to surface-treat the glass tube with an acidic solution having a pH value of 3-6 or an alkaline solution having a pH value of 8-12.

Description

  The present invention relates to a method for manufacturing a semiconductor encapsulating outer tube, and more specifically to a method for manufacturing a semiconductor enclosing outer tube used for encapsulating semiconductor elements such as silicon diodes, light emitting diodes, and thermistors.

Semiconductor elements such as thermistors, diodes, and LEDs need to be hermetically sealed. Conventionally, lead tubes made of lead glass have been used for hermetically sealing semiconductor elements. In recent years, SiO ₂ —B ₂ O ₃ —R ₂ O introduced in Patent Literature 1 and Patent Literature 2 have been used. A product made of lead-free glass having a composition (R is an alkali metal element) has also been proposed.

  The outer tube for encapsulating a semiconductor is made by melting a glass raw material in a melting furnace, forming the molten glass into a tubular shape, then cutting the obtained glass tube into a length of about 2 mm, washing it, and cleaning it. Getting a tube. The assembly of the semiconductor encapsulated component is performed by inserting a semiconductor element and a metal wire such as a dumet wire into a mantle tube and heating. By this heating, the glass is softened at the end portion of the outer tube, the metal wire is sealed, and the semiconductor element can be hermetically sealed in the tube. The semiconductor encapsulated part thus manufactured is subjected to acid treatment, plating treatment, or the like for the purpose of removing the oxide film of the metal wire exposed outside the tube.

  The glass for semiconductor encapsulation that constitutes the outer tube for semiconductor encapsulation includes (1) low temperature so that the element does not deteriorate or the metal wire contact failure due to loss of elasticity beyond the yield point of the metal occurs. (2) It has a thermal expansion coefficient that matches the thermal expansion coefficient of the metal wire, (3) Adhesiveness between the glass and the metal wire is sufficiently high, (4) The volume resistance is high, (5) Characteristics such as sufficiently high chemical resistance, particularly acid resistance are required so as not to be deteriorated by acid treatment, plating treatment or the like.

JP-A-2002-37641 US Pat. No. 7,102,242

Conventionally, the reason why lead glass has been adopted as a material for the outer tube is that it is easy to lower the melting point. Moreover, lead glass is excellent in sulfuric acid resistance because a lead sulfate layer hardly soluble in sulfuric acid is formed on the glass surface when it comes into contact with a sulfuric acid solution. Therefore, the outer tube surface is not deteriorated by the acid treatment or the plating treatment after the semiconductor element is sealed. However, the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass has a drawback in that the acid resistance is low because a layer hardly soluble in sulfuric acid is not formed on the surface. When glass with low acid resistance is acid-treated or plated, the glass surface deteriorates and fine cracks are generated. If such a crack exists on the glass surface, various stains and moisture are likely to adhere to the surface of the glass, and the surface resistance of the device may be lowered, resulting in a malfunction of the electrical product. However, if the content of the skeletal component of the glass such as SiO ₂ in the glass composition is increased or the content of the alkali metal component is decreased in order to improve acid resistance, low-temperature encapsulation becomes difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a semiconductor encapsulation envelope capable of encapsulating a semiconductor element at a low temperature and excellent in acid resistance, and to provide a semiconductor encapsulation envelope manufactured by this method. .

Results of the study by the present _inventors, oxidation barrier layer mantle tube manufactured in low viscosity _{SiO 2 -B 2 O 3 -R 2} O -based lead-free glass containing B 2 _{O 3} in a large amount and a surface treatment with a liquid It is found that the above-mentioned problems can be solved by forming the, and is proposed as the present invention.

The manufacturing method of the outer tube for semiconductor encapsulation of the present invention includes a step of producing a glass tube with SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass, and a surface treatment of the glass tube with an acidic solution or an alkaline solution. And a process. “R ₂ O” means Li ₂ O, Na ₂ O and / or K ₂ O which are alkali metal oxides. “Lead-free” means that a lead raw material is not actively added as a glass raw material, and does not completely exclude contamination from impurities. More objectively, it can be defined that the content of PbO contained in the glass is 0.1% by mass or less including impurities. “Acid solution” means a solution having a pH of 6 or less, and “alkaline solution” means a solution having a pH of 8 or more.

  The mechanism by which the acid degrades the glass is considered as follows. First, protons in the acidic solution ion exchange with the alkali metal component in the glass. Further, the Si component forming the glass network structure is hydrated and the glass structure is weakened. Further, a network component other than Si, such as B component, dissolves to form Si gel. When this diffuses into the solution and a new surface is created, ion exchange begins again. Therefore, if the ion exchange reaction between protons and the alkali metal component in the glass can be suppressed, the acid resistance of the glass can be improved.

  Therefore, in the present invention, an alkali exchange component on the glass surface is ion-exchanged with protons by surface treatment to form an ion exchange layer having a low alkali metal component content on the glass surface. The presence of this ion exchange layer makes it difficult to cause an ion exchange reaction in the subsequent acid treatment or plating treatment.

In the method of the present invention, the temperature corresponding to the viscosity of 10 ⁶ dPa · s of the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass is preferably 650 ° C. or less. Here, “temperature corresponding to a viscosity of 10 ⁶ dPa · s” means a temperature obtained by the following method. First, the softening point is measured by a fiber method conforming to ASTM C338. Further, a temperature corresponding to the viscosity of the working point region is obtained by a platinum ball pulling method. Next, these viscosities and temperatures are applied to the Fulcher equation to calculate the temperature at 10 ⁶ dPa · s. Note that a temperature corresponding to a viscosity of 10 ⁶ dPa · s corresponds to a temperature at which the semiconductor element is sealed.

  In the method of the present invention, the surface treatment is particularly preferably performed using an acidic solution having a pH of 3 to 6 or an alkaline solution having a pH of 8 to 12.

  As described above, the content of the alkali metal component on the glass surface can be reduced by previously ion-exchanging the glass surface. However, if ion exchange is performed more than necessary, a hard layer mainly composed of Si is formed on the glass surface. When the inner surface of the outer tube is softened by heat treatment at the time of encapsulating the semiconductor element, the surface area is reduced and the inner diameter is reduced, the hard layer is difficult to soften, so it is likely to be folded and looks like white wrinkles. This wrinkle causes poor airtightness.

  Adopting the above configuration in such a case makes it easy to selectively elute alkali to the extent that excessive ion exchange reaction is suppressed and the network structure of the glass is not destroyed. Further, a hard layer containing Si as a main component is hardly formed on the surface, and wrinkles are hardly generated on the outer tube surface even when heat treatment for element encapsulation is performed.

In the method of the present invention, it is preferable to prepare a glass tube with SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass having a composition of B ₂ O ₃ of 15.5 mol% or more. More specifically, in _{mol%, SiO 2 46~60%, Al} 2 O 3 0~6%, B 2 O 3 15.5~30%, 0~10% MgO, CaO 0~10%, ZnO _{0~20%, Li 2 O 0~25%} , Na 2 O 0~15%, K 2 O 0~7%, SiO 2 -B 2 O 3 -R 2 O -based lead-free, containing TiO 2 0 to 8% It is preferable to produce a glass tube with glass.

In the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass, B ₂ O ₃ has an effect of lowering the sealing temperature (temperature corresponding to a viscosity of 10 ⁶ dPa · s). On the other hand, B ₂ O ₃ is a component that lowers the acid resistance of the glass. Thus by applying the method of the present invention in the case of manufacturing a _{SiO 2 -B} 2 _O 3 -R 2 semiconductor encapsulating cannula with O-based lead-free glass containing _B 2 _{O 3} in a large amount, enjoys a remarkable effect be able to.

  The outer tube for semiconductor encapsulation of the present invention is manufactured by the above method.

  The outer tube manufactured by the above method has an ion exchange layer with a low alkali content formed on the surface thereof, and this layer functions as an acid-resistant barrier layer.

  A semiconductor encapsulating tube manufactured by using the method of the present invention can encapsulate a semiconductor element at a low temperature. Moreover, since it is excellent in acid resistance, even if an acid treatment is performed after element encapsulation, a highly reliable semiconductor encapsulated part can be produced because fine cracks on the surface due to ion exchange hardly occur.

The method of the present invention comprises a step of producing a glass tube using SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass having a temperature corresponding to a viscosity of 10 ⁶ dPa · s of 650 ° C. or less, and the glass Surface treating the tube with an acidic or alkaline solution.

First, a process for producing a glass tube using SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass having a temperature corresponding to a viscosity of 10 ⁶ dPa · s of 650 ° C. or less will be described.

The SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass used in this step preferably has a temperature corresponding to a viscosity of 10 ⁶ dPa · s of 620 to 650 ° C., particularly 620 to 635 ° C. The viscosity temperature of 10 ⁶ dPa · s generally corresponds to the sealing temperature of the semiconductor element. Therefore, the outer tube manufactured by the method of the present invention can enclose the semiconductor element at 650 ° C. or lower. In addition, in order to make the temperature of the viscosity of 10 ⁶ dPa · s to 650 ° C. or less, it can be achieved by containing a large amount of Li ₂ O among alkali components, a large amount of B ₂ O _3, and the like. .

The SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass preferably has a temperature corresponding to a viscosity of 10 ² dPa · s of 1000 ° C. or less, particularly 950 to 965 ° C. The temperature corresponding to a viscosity of 10 ² dPa · s is a temperature for melting the glass. Therefore, the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass used in the present invention can be melted at a low temperature while suppressing energy consumption. In order to set the temperature corresponding to the viscosity of 10 ² dPa · s to 1000 ° C. or less, it can be achieved by increasing the amount of alkali metal oxide or ZnO. In particular, in order to make this temperature 965 ° C. or lower, it is desirable to make ZnO 7.4% or higher.

The SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass preferably has a thermal expansion coefficient in the range of 30 ° C. to 380 ° C. of 85 to 105 × 10 ⁻⁷ / ° C. in order to seal with dumet. .

The SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass preferably has a volume resistance as high as possible. Specifically, the volume resistance value at 150 ° C. is preferably 7 or more, particularly 9 or more, and more preferably 10 or more in Logρ (Ω · cm). When a diode or the like is used at a high temperature of about 200 ° C., the volume resistance value at 250 ° C. is preferably 7 or more in Log ρ (Ω · cm). If the volume resistance of glass is low, for example, in the case of a diode, a slight amount of electricity flows between the electrodes, resulting in a circuit as if a resistor was installed in parallel with the diode.

As the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass having a temperature corresponding to a viscosity of 10 ⁶ dPa · s of 650 ° C. or less, SiO ₂ having a composition of 25.5 mol% or more of B ₂ O ₃ is used. _2- B ₂ O ₃ —R ₂ O-based lead-free glass, more specifically, mol%, SiO ₂ 46-60%, Al ₂ O ₃ 0-6%, B ₂ O ₃ 15.5-30% _{, 0~10% MgO, CaO 0~10%} , 0~20% ZnO, Li 2 O 0~25%, Na 2 O 0~15%, K 2 O 0~7%, TiO 2 0~8% content SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass can be suitably used. In addition, the said composition is an example and is not limited to this range.

  The reason why the glass composition is limited to the above range will be described below. In addition, the following% display points out mol% unless there is particular notice.

SiO ₂ is a main component and an important component for stabilizing the glass. It also has a great effect on improving acid resistance. On the other hand, SiO ₂ is also a component that raises the sealing temperature. The content of SiO ₂ is 46 to 60%, preferably 46 to 59.9%, more preferably 48.2 to 57.9%, and further preferably 50.2 to 53.7%. When the content of SiO ₂ is too small it becomes difficult to enjoy the effects described above. On the other hand, if the SiO ₂ content is too large, low-temperature encapsulation becomes difficult.

Al ₂ O ₃ is a component that suppresses precipitation of crystals containing Si and increases water resistance. On the other hand, Al ₂ O ₃ is also a component that increases the viscosity of the glass. The content of Al ₂ O ₃ is 0 to 6%, preferably 0.1 to 4%, more preferably 0.4 to 3%. If the content of Al ₂ O ₃ is too small, the above effect cannot be obtained. On the other hand, if the content of Al ₂ O ₃ is too large, the viscosity of the glass becomes too high and the moldability tends to be lowered. Also, low temperature encapsulation becomes difficult.

B ₂ O ₃ is a component that stabilizes the glass and lowers the viscosity of the glass. On the other hand, B ₂ O ₃ is also a component that lowers chemical resistance. The content of B ₂ O ₃ is 15.5 to 30%, preferably 15.8 to 25%, more preferably 16.1 to 18.2%. If the content of B ₂ O ₃ is too small it becomes difficult to enjoy the effects described above. On the other hand, when the content of B ₂ O ₃ is too large, the acid resistance is deteriorated.

Alkaline earth metal oxides (MgO, CaO, SrO, BaO) have a high effect of stabilizing the glass. On the other hand, in a glass having a temperature corresponding to a viscosity of 10 ⁶ dPa · s of 650 ° C. or lower, the effect of reducing the temperature of the glass by the alkaline earth metal oxide cannot be expected, and the encapsulation temperature may be increased. . For this reason, it is preferable that the total amount of the alkaline earth metal oxide is small, and the total content is preferably 0 to 10%, 0 to 8%, particularly preferably 0 to 6%. Each alkaline earth metal oxide component is described below.

  The contents of MgO and CaO are each 0 to 10%, preferably 0 to 5%, more preferably 0 to 2%. When there is too much content of MgO or CaO, the viscosity of glass will become high and it will become difficult to fuse | melt. CaO has the effect of improving chemical resistance in addition to the effects common to the alkaline earth metal oxides described above.

  ZnO is a component that can lower the viscosity of the glass without increasing the expansion and without deteriorating the acid resistance as compared with the alkali metal oxide. The content of ZnO is 0 to 20%, preferably 1 to 15%, more preferably 2 to 12%. When there is too much ZnO, it will become easy to devitrify glass.

Alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) have the effect of lowering the viscosity of the glass or increasing the expansion. In particular, Li ₂ O is preferably used as an essential component in the glass having the above composition because the glass has a high effect of reducing the viscosity of the glass and the glass does not shrink much even when ion exchange is performed with a small ion radius. . On the other hand, if the total amount of the alkali metal oxide is too large, the expansion becomes too high and a crack is generated between the metal wires such as dumet. Moreover, the acid resistance of glass is deteriorated. Therefore, the total amount of alkali metal oxides is preferably 10 to 30%, particularly 20 to 30% and 21 to 28%. Each alkali metal oxide component will be described below.

As described above, Li ₂ O has a large effect of reducing the viscosity of the glass, and since the ion radius is small, the moving speed in the glass is large and cracks are not easily generated. Therefore, as much as possible is introduced to enhance the effect of the present invention. It is desirable to do. When the content is increased, crystals containing Li are likely to be produced, but there is an effect of relaxing the alkali reduction rate more than other alkalis and wrinkles can be improved. For this reason, the content of Li ₂ O is 0 to 25%, preferably 0.1 to 25%, more preferably 4 to 20%, particularly preferably 5 to 19%, and further preferably 9 to 19%. When the Li 2 _O content is too small it becomes difficult to enjoy the effects described above. On the other hand, easily devitrified when the content of Li 2 _O is too large.

Further, as described above, Li ₂ O has the highest effect of lowering the viscosity of the glass and the effect of preventing the occurrence of cracks. Therefore, in the present invention, the proportion of Li ₂ O in the total amount of the alkali metal oxide is set to a certain level or more. Is desirable. When Li ₂ O is contained, the value of Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) is 0.05 to 0.9, particularly 0.1 to 0.9, and even 0.3 on a mol% basis. It is preferable to set it to -0.8. If this value is too large, crystals may be formed in the glass.

Further, from the viewpoint of lowering the sealing temperature, the value of Li ₂ O / SiO ₂ is 0.05 to 0.5, particularly 0.1 to 0.4, more preferably 0.15 to 0.35 on a mol% basis. It is preferable to do. If this value is too small, encapsulation at 650 ° C. becomes difficult. Conversely, if the value is too large, crystals may form in the glass and cause devitrification.

Na ₂ O has the effect of stabilizing the glass and preventing devitrification in addition to the effects common to the alkali metals described above, and it is desirable to introduce it in consideration of the stabilization of the glass. The content of Na ₂ O is 0 to 15%, preferably 1 to 15%, more preferably 2 to 13%, and further preferably 5 to 11%. When the Na 2 _O content is too small it becomes difficult to enjoy the effects described above. On the other hand, when the content of Na 2 _O is too large, easily devitrified.

K ₂ O has the effect of stabilizing the glass and preventing devitrification in addition to the effects common to the alkali metals described above. On the other hand, K ₂ O tends to cause cracks compared to Li ₂ O. In addition, the effect of reducing the viscosity of the glass is small. The content of K ₂ O is 0 to 7%, preferably 0.6 to 3%, more preferably 0.6 to 2.3%. When the content of K 2 _O is too large easily devitrified.

TiO ₂ is a component added to increase acid resistance. On the other hand, TiO ₂ has a feature that it tends to deteriorate the devitrification resistance of the glass. For this reason, if TiO ₂ is contained excessively, the glass is easily devitrified by contact with a metal or a refractory, and there is a possibility that the dimensional accuracy of the glass obtained due to the influence of the devitrified material is lowered. The content of TiO ₂ is 0 to 8%, preferably 0.6 to 5%, more preferably 1.1 to 5%, and still more preferably 1.1 to 4%.

In order to improve acid resistance, the total content of SiO ₂ and TiO ₂ is preferably 48.5 to 61%, particularly 51 to 58%, more preferably 52.1 to 56.5%. If the total amount of SiO ₂ and TiO ₂ is too small, there is no effect in improving acid resistance. If the total amount of SiO ₂ and TiO ₂ is too large, the glass becomes hard and difficult to encapsulate at low temperatures.

In addition to the above components, various components can be added as long as the properties of the glass are not impaired. For example, CeO ₂ can be added as a fining agent. In this case, the CeO ₂ content is preferably 0 to 5%, particularly preferably 0.1 to 3%. Also, to reduce glass viscosity, F is up to 0.5%, Bi ₂ O ₃ is up to 25%, La ₂ O ₃ is up to 10%, and ZrO ₂ is up to 5% to improve chemical resistance. Can be made. However, environmentally undesirable components such as As ₂ O ₃ and Sb ₂ O ₃ should not be added. Specifically, the content of As ₂ O ₃ or Sb ₂ O ₃ is limited to 0.1% or less.

When producing a glass tube using a SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass on an industrial scale, it can be performed, for example, as follows. In addition, the following method is an illustration and this invention is not limited to this.

  First, glass raw materials are prepared and mixed. The raw materials are composed of minerals and impurities composed of a plurality of components such as oxides and carbonates, and may be prepared in consideration of the analytical values, and the raw materials are not limited. These are measured in terms of weight and mixed with an appropriate mixer according to the scale, such as a V mixer, a rocking mixer, or a mixer equipped with stirring blades, to obtain an input raw material.

Next, the raw material is put into a glass melting furnace and vitrified. A melting furnace is used to melt a glass raw material into a vitrification tank, a clarification tank for ascending and removing bubbles in the glass, and lowering the clarified glass to a viscosity suitable for molding and leading it to a molding apparatus. It is common to have a passage (feeder). As the melting furnace, a refractory material or a furnace covered with platinum is used, and it is heated by heating with a burner or electric current to glass. The charged raw materials are usually vitrified in a melting tank at 1100 ° C. to 1600 ° C., and further enter a clarification tank at 1100 ° C. to 1400 ° C. Here, bubbles in the glass are lifted to remove the bubbles. The glass that comes out of the Kiyosumi pass is cooled to a viscosity of 10 ⁴ to 10 ⁶ dPa · s, which is suitable for glass molding, as it moves to the molding apparatus through the feeder.

  Next, the glass is formed into a tubular shape with a forming apparatus. As a molding method, a Danner method, a tongue method, a downdraw method, and an updraw method can be applied.

  After that, the glass tube is cut into a predetermined size to obtain a bead-shaped semiconductor encapsulating outer tube. The glass tube can be cut one by one with a diamond cutter. However, as a method suitable for mass production, a large number of tube glasses are bound together and then cut with a diamond wheel cutter. A method of cutting a large number of tube glasses at a time is generally used.

  Next, the process of surface-treating the glass tube with an acidic solution or an alkaline solution will be described.

  The acidic solution used as the treatment liquid in this step has a pH of 6 or less, and the alkaline solution has a pH of 8 or more. By treating the glass surface with an acidic solution or an alkaline solution, an ion exchange layer is formed on the glass surface, which functions as a barrier layer.

  However, if the treatment solution is too acidic or alkaline, the glass network structure may be destroyed, and the acid resistance improvement effect may be lost or wrinkles may occur. It is therefore preferable to use acidic solutions with a pH of 3-6, in particular pH 4-6, or alkaline solutions with a pH of 8-14, in particular of pH 8-13, more preferably of pH 8-12. In particular, it is desirable to use a weak alkaline solution. If the glass surface is treated with a weakly acidic solution or a weakly alkaline solution, the elution rate of the alkali metal component can be reduced. As a result, the rate of decrease in the content of alkali metal components from the outermost surface of the glass to the inside of the glass becomes gradual, and the generation of wrinkles due to the difference in composition between the outermost surface and the inside can be effectively suppressed.

  The temperature of the treatment liquid used in this step is not limited, but is preferably 40 ° C. or higher, particularly 60 ° C. or higher, and more preferably 70 ° C. or higher. The processing time can be shortened as the temperature of the processing liquid increases. The upper limit of the temperature of the treatment liquid is preferably 100 ° C. When the temperature of the treatment liquid is low, it is difficult to produce an ion exchange layer that functions as a barrier layer. On the other hand, if the temperature of the treatment liquid is too high, it is difficult to perform a stable treatment.

  Note that the shorter the processing time, the higher the production efficiency and the better. However, if the processing time is too short, it becomes difficult to perform a stable processing. Therefore, the processing time is desirably about 2 minutes or more.

  As a method for surface-treating the glass tube with the above treatment liquid and treatment conditions, for example, the following method can be employed.

First, a glass tube (bead) molded and cut to a predetermined size is immersed in a processing solution, held for a certain time, and then pulled up from the processing solution. As the acidic solution used as the treatment liquid, an aqueous solution such as HCl, H ₂ SO ₄ , HNO ₃ , and CH ₃ COOH can be used. As the alkaline solution, an aqueous solution of NaOH, KOH, NH ₄ OH or the like can be used. These aqueous solutions may contain additives such as surfactants as necessary. Specific processing conditions are exemplified below.
(1) Immerse in a weak alkaline solution (70 ° C., pH 10) and rock for 5 minutes. Next, ultrasonic vibration is performed for 5 minutes in an alkaline surfactant solution (60 ° C., pH 10) containing the surfactant. Subsequently, it is washed with ion-exchanged water (room temperature) for 5 minutes × 5 times.
(2) Immerse in a weakly acidic solution (50 ° C., pH 4) for 5 minutes. Next, it is immersed for 5 minutes in the alkaline solution (80 degreeC, pH10) containing surfactant. Subsequently, it is washed with ion exchange water (room temperature) for 5 minutes × 3 times.
(3) Immerse in an alkaline solution (50 ° C., pH 12) containing a surfactant for 5 minutes. Then, it is washed with ion exchange water (50 ° C.) for 5 minutes × 3 times.

  Thereafter, the outer tube pulled up from the treatment liquid is dried to obtain the outer tube for semiconductor encapsulation of the present invention. The drying temperature may be a temperature at which the glass is not deformed, and for example, it can be processed at a strain point.

  The outer tube manufactured by the above method has an ion exchange layer with a low alkali content formed on the surface thereof, and this layer functions as an acid-resistant barrier layer. In this ion exchange layer, it is desirable that the content of the alkali component gradually decreases from the surface toward the inside, and the content of the Si component gradually increases. In order to prevent wrinkles, it is desirable that the change in the content of these components is continuous.

  The thickness of the ion exchange layer (acid-resistant barrier layer) is preferably 1 nm or more, particularly 10 nm or more in order to exhibit acid resistance, while it is preferably 1 μm or less in order to prevent wrinkles.

Further, Na ₂ O on the outermost surface is 0.9 times or less, particularly 0.6 times or less, more preferably 0.6 times or less when the measured intensity of Na ₂ O inside the ion exchange layer is set to 1 in depth profile analysis by SIMS. It is desirable that it is 3 times or less. From the viewpoint of preventing wrinkles, this value is preferably 0.01 times or more, particularly 0.1 times or more, and more preferably 0.2 times or more. Further, the outermost surface Li ₂ O should be 0.9 times or less, particularly 0.6 times or less, more preferably 0.3 times or less when the measured Li ₂ O intensity inside the ion exchange layer is 1. desirable. From the viewpoint of preventing wrinkles, this value is preferably 0.01 times or more, particularly 0.1 times or more, and more preferably 0.2 times or more. Further, SiO _{2 on} the outermost surface of the glass should be 1.1 times or more, particularly 1.5 times or more, more preferably 2.0 times or more when the measured SiO ₂ strength inside the ion exchange layer is 1. desirable. Here, the inside of the ion exchange layer means the inside of the depth at which the content does not change when the depth profile of Si or an alkali metal component is analyzed by secondary ion mass spectrometry (SIMS). This depth can be based on, for example, a depth of 100 nm from the surface. In consideration of the case where the boundary of the ion exchange layer is difficult to discriminate, it is preferable to use a depth of 400 nm as a reference. In addition, when it is determined that the surface is contaminated, for example, when the alkali content that decreases continuously increases on the surface or when C is detected, the minimum value of the depth profile of Na is defined as the surface.

  Next, a method for encapsulating a semiconductor element using a semiconductor encapsulating tube manufactured by the method of the present invention will be described.

  First, in a mantle tube, a metal wire such as a jumet wire is set using a jig so that a semiconductor element is sandwiched from both sides. Thereafter, the whole is heated to a temperature of 650 ° C. or lower, and the outer tube is softened and deformed to hermetically seal the semiconductor element.

  By the way, in the hermetically sealed semiconductor device manufactured by the above method, an oxide film is formed on the surface of the end portion of the metal wire exposed to the outside due to the heat treatment. In this state, solder coating, Sn plating, Ni plating are performed. Etc. cannot be applied. Therefore, an acid treatment is performed on the hermetic seal and the oxide film formed on the end surface of the metal wire is peeled off. As acid treatment, it is treated with organic sulfonic acid at 50 ° C. for 5 to 10 minutes, or treated with 80% by mass of 36N sulfuric acid and 0.1% by mass of hydrogen peroxide (15%) and treated at 80 ° C. for 20 seconds. , 36N sulfuric acid 5% is used at 20 to 80 ° C. for 1 minute.

  Subsequently, the air-tight sealed body from which the oxide film of the metal wire is removed is washed with city water, and then the metal wire end portion is coated through a process such as Sn, Ni sulfate plating, or solder dipping, so that a silicon diode, Small electronic components such as light emitting diodes and thermistors can be manufactured.

  Hereinafter, the present invention will be described based on examples. In addition, this invention is not limited to the following Example.

Table 1 shows a composition example of the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass used in the present invention.

  Each sample was prepared as follows. First, glass raw materials were prepared so as to have the glass composition described in the table, melted at 1200 ° C. for 3 hours using a platinum pot, molded, and subjected to various evaluations. As the glass raw material, silica powder, aluminum oxide, boric acid, zinc oxide, lithium carbonate, sodium nitrate, potassium carbonate, titanium oxide, cerium oxide and the like were used.

Next, the temperature at a coefficient of thermal expansion of 10 ⁶ dPa · s was evaluated for the obtained sample. The results are shown in Table 1.

  Next, using the method of the present invention, Sample No. 1 and no. An outer tube sample made of 8 glasses was prepared.

  Next, the acid resistance before and after heat treatment was evaluated for the obtained samples. The heat treatment was assumed to encapsulate the semiconductor element, and was performed by placing the surface-treated sample on a carbon plate and placing it in a furnace maintained at the encapsulation temperature for 8 minutes. By this heat treatment, the end surface portion of the sample is softened and deformed to be rounded, and the inner diameter contracts to about 1/3 to half.

  The surface treatment was performed under the following conditions. First, a glass tube molded to a size of 1.4 × 0.9 × φ1.5 mm is placed in a stainless steel jar having an opening of 1 mm and immersed in an aqueous solution containing a surfactant (50 ° C., pH 12) for 5 minutes. And washed with ion exchange water (50 ° C.) for 5 minutes × 3 times. Thereafter, the glass tube was put into a dryer and dried at 200 ° C. to obtain a sample.

For comparison, the acid resistance of the glass tube before the surface treatment was also evaluated by the same method. The results are shown in Table 2.

  As apparent from Table 2, the outer tube sample produced by the method of the present invention had good acid resistance. Moreover, about the sample after heat processing, when the surface was observed with the optical microscope of 40 time, a wrinkle was not recognized.

  The thermal expansion coefficient is a value obtained by measuring an average linear thermal expansion coefficient in a temperature range of 30 to 380 ° C. with a thermal dilatometer using a cylindrical measurement sample having a diameter of about 3 mm and a length of about 50 mm.

The enclosure temperature was determined as follows. First, the softening point was measured by a fiber method conforming to ASTM C338. Next, a temperature corresponding to the viscosity of the working point region was determined by a platinum ball pulling method. Finally, these viscosities and temperatures were applied to the Fulcher equation to calculate the temperature at 10 ⁶ dPa · s, which was used as the sealing temperature. The temperature at 10 ² dPa · s was determined in the same manner.

  The acid resistance was evaluated as follows. First, three samples were each immersed in a 20% by mass solution of 36N sulfuric acid for 60 seconds, washed with ion-exchanged water for 60 seconds, and dried at 120 ° C. for 2 hours or more. Thereafter, the surface of the sample was observed with a 100-fold microscope, and the number of cracks at the three randomly viewed surfaces was totaled. The case where it was 1 or less was designated as “◯” and the case where it was 2 or more was designated as “X”.

  Next, the sample No. When the depth profile of Si, Na, and Li on the outer surface was examined by secondary ion mass spectrometry (SIMS), a surface layer of about 50 nm was detected, and the measured intensity of the surface portion with respect to a depth of 100 nm was 1 In the case of Si, it was confirmed that Na and Li were 0.2 times each. Moreover, it turned out that each component is changing continuously.

  The method of the present invention is suitable as a method for producing a glass mantle used for enclosing semiconductor elements such as silicon diodes, light emitting diodes, thermistors, surge absorbers and the like.

Claims (6)

A sheath for encapsulating a semiconductor, comprising: a step of producing a glass tube with SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass, and a step of surface-treating the glass tube with an acidic solution or an alkaline solution. A method of manufacturing a tube. The temperature corresponding to the viscosity of 10 ⁶ dPa · s of the SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass is 650 ° C. or less, The manufacture of the outer tube for semiconductor encapsulation according to claim 1, Method. 3. The method for producing an outer tube for semiconductor encapsulation according to claim 1, wherein the surface treatment is performed using an acidic solution having a pH of 3 to 6 or an alkaline solution having a pH of 8 to 12. The glass tube is made of SiO ₂ —B ₂ O ₃ —R ₂ O-based lead-free glass having a composition of B ₂ O ₃ of 15.5 mol% or more. The manufacturing method of the outer tube for semiconductor enclosure of description. In _{mol%, SiO 2 46~60%, Al} 2 O 3 0~6%, B 2 O 3 15.5~30%, 0~10% MgO, CaO 0~10%, 0~20% ZnO, Li _The glass tube is made of SiO ₂ —B ₂ O ₃ —R ₂ O based lead-free glass containing ₂ O 0 to 25%, Na ₂ O 0 to 15%, K ₂ O 0 to 7%, TiO ₂ 0 to 8%. The method for manufacturing a semiconductor encapsulating mantle according to claim 1, wherein the manufactured outer tube is manufactured. An outer tube for semiconductor encapsulation, which is manufactured by the method according to claim 1.