JP2005039163A - Circuit board for mounting semiconductor device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board capable of preventing malfunctions and operation stops caused by the heat of a semiconductor device by closely joining a thermal via, an Al housing and a radiator and making the function of various kinds of electronic equipment normal and stable using a circuit board for mounting semiconductor devices and an electronic device for a long term. <P>SOLUTION: The circuit board for mounting semiconductor devices comprises the mounting section of the semiconductor device 7 consisting of a conductor layer formed on one main surface of an insulating board; a heat transfer layer 4 that is formed on the other main surface of the insulating board, is connected to the mounting section via a penetrated conductor 3, and contains a glass constituent; a resistor layer 5 that is formed at a part adjacent to the heat transfer layer 4 on the other main surface and contains the glass constituent; and a protection glass layer 6 for covering the resistor layer 5. In this case, the heat transfer layer 4, the resistor layer 5, and the protection glass layer 6 are simultaneously baked and T<SB>1</SB>>T<SB>3</SB>>T<SB>2</SB>is satisfied when the softening point of the glass constituent contained in the heat transfer layer 4, that contained in the resistor layer 5, and that contained in the protection glass layer 6 are set to be T<SB>1</SB>, T<SB>2</SB>, and T<SB>3</SB>, respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor element mounting circuit board capable of operating the functions of a semiconductor element and a circuit board to be mounted normally and stably over a long period of time.

  2. Description of the Related Art Conventionally, a ceramic wiring board in which a wiring conductor is formed on an insulating base made of ceramics is well known as a wiring board for mounting semiconductor elements such as IC and LSI, electronic components, and the like.

  This ceramic wiring board is manufactured as follows by employing a ceramic green sheet (hereinafter also referred to as green sheet) lamination method. First, glass powder, organic binder, solvent, plasticizer, etc. are added to the ceramic raw material powder to form a mud, which is then formed into a sheet by the doctor blade method, calendar roll method, etc., and then green sheet (ceramic raw sheet) On the surface of the green sheet, a desired glass as a metal powder such as gold (Au), silver (Ag), palladium (Pd), platinum (Pt), copper (Cu), tungsten (W), molybdenum (Mo) A metal paste obtained by adding and mixing powder, an organic binder, a solvent, a plasticizer and the like is printed and applied in a predetermined pattern by a screen printing method. Thereafter, a plurality of the green sheets are laminated to form a laminate, and the laminate is manufactured by firing at a temperature of about 800 to 1600 ° C.

  Further, in order to form the resistor layer, a thick film printing method is used to print and form a pace that becomes the resistor layer in a desired shape, and baking is performed at 500 to 900 ° C. Thereafter, in order to form a protective glass layer on the ceramic multilayer substrate on which the resistor layer is formed, a paste containing glass is printed and applied so as to cover the resistor layer by using a thick film printing method, and 400 to 700 ° C. Bake to form.

  In addition, in a wiring board used in an in-vehicle device for an automobile or the like, the amount of heat generated by an IC chip mounted on a circuit board for mounting a semiconductor element (hereinafter also simply referred to as a circuit board) is increased as the in-vehicle device becomes more sophisticated. In order to cool the heat generation of the IC chip, the method of cooling by moving the heat to the surface opposite to the IC chip mounting surface by providing a thermal via in the circuit board, When heat dissipation is insufficient, the circuit board is bonded to the aluminum (Al) housing or heat radiator (heat pipe) via grease, and heat is dissipated from the Al housing or heat radiator (heat pipe). Has generally been adopted.

  Such a circuit board is manufactured as follows. First, in order to form a resistor layer on the fired ceramic multilayer substrate, a paste that becomes the resistor layer is printed and formed into a desired shape using a thick film printing method, and is baked at 500 to 900 ° C. Thereafter, in order to form a protective glass layer on the ceramic multilayer substrate on which the resistor layer is formed, the resistor layer is covered with a paste containing glass using a thick film printing method, and is printed and applied in a desired shape. Bake at ℃.

Further, as another manufacturing method, a thick film printing method is used to form a resistor layer on a fired ceramic multilayer substrate, and a paste that becomes the resistor layer is printed and formed in a desired shape at 50 to 150 ° C. A method of drying and coating the resistor layer with a paste containing glass that subsequently becomes a protective glass layer and printing and coating the resistor layer and the protective glass layer simultaneously at 500 to 900 ° C. is also widely known.
JP-A-8-153945 JP-A-8-250623 Japanese Patent Laid-Open No. 8-250829

  However, in a circuit board having a resistor layer formed by a thick film printing method, a protective glass layer covering the resistor layer is coated to protect the resistor layer from external impact, moisture, and foreign matter. Is generally done. In this configuration, when the circuit board is bonded to the Al housing or the heat radiating body, a protective glass layer exists between the thermal via and the Al housing or the heat radiating body, thereby preventing heat conduction. The thermal conductivity of a general protective glass layer is 4 to 5 W / mK. Compared with 10 to 20 W / mK for thermal vias and 40 to 50 W / mK for Al, which is the material of the Al housing, it is also effective for heat conduction. It turns out that it becomes a big obstacle. Therefore, in this configuration, the heat generated from the IC chip cannot be sufficiently dissipated due to further higher heat generation of the IC chip in the future, so that the temperature of the operating IC chip itself rises and the IC chip malfunctions and operates. The occurrence of the problem of stopping will be fully expected.

  Moreover, as a configuration for improving heat dissipation, a configuration in which a protective glass layer is not applied to the lower portion of the thermal via may be adopted. However, in this configuration, when the circuit board is bonded to the Al housing or the radiator, the thermal via and the Al Since the housing and the heat radiator are directly joined, heat conduction is relatively good. However, in this configuration, a step with the protective glass layer is formed in the lower portion of the thermal via and a recess is formed. For this reason, when the circuit board is mounted on the Al housing or the heat radiating member with grease, bubbles are caught in the recess. For this reason, there is a problem in that the bubble entrained air bubbles exist between the thermal via and the Al housing or the heat radiating body, and as a result, the heat conductivity is greatly reduced. .

  In addition, a protective glass layer is not applied to the bottom of the thermal via, and a convex part is formed by joining a metal or a high heat conductive material component directly below it via an adhesive material such as solder or epoxy resin. The structure which did not involve is also taken. However, in the heat transfer layer after the convex portion is formed, the coplanarity (flatness) of the heat transfer layer attached to each of the thermal vias existing on the substrate surface is not stable, so that the circuit board becomes an Al housing or a radiator. When mounted, a part of the heat transfer layer does not come into contact with the Al housing or the radiator, and as a result, there is a problem that the thermal conductivity is lowered.

  In addition, a configuration in which a metal or high thermal conductive material component is joined in advance via a brazing material such as solder or an adhesive made of an epoxy resin to form a convex portion, and then a resistor layer is formed immediately below the thermal via. However, the resistor layer is generally formed by a printing method, and in this method, the heat transfer layer protrudes as a convex portion when printing the paste to be the resistor layer. Therefore, there is a problem that the printing thickness of the paste serving as the resistor layer is not uniform, and the resistance value of the resistor layer varies.

  Further, in the conventional circuit board manufacturing method, the printed resistor body, the protective glass layer, and the heat transfer layer are fired, respectively, so that the energy consumption is large and appropriate from the viewpoint of environmental protection. It is not a manufacturing method.

  Moreover, the flow of the manufacturing process is firing of the resistor layer, printing of the protective glass layer, firing of the protective glass layer, printing of the heat transfer layer, and firing of the heat transfer layer, and the printing process and the firing process are alternately performed. The behavior of the paste that becomes the printed resistor layer, the paste that becomes the protective glass layer, and the paste that becomes the heat transfer layer during firing is generally accompanied by shrinkage and deformation. Therefore, in the conventional manufacturing method, the fired resistor layer is contracted or deformed, and a protective glass layer is printed thereon, which causes a positional shift in a product requiring high accuracy. .

  However, since it is expected that the circuit board manufactured by the above-described conventional manufacturing method cannot sufficiently dissipate the heat generated from the IC chip due to the high heat generation of the IC chip in the future, the IC chip in operation There is a high possibility that the temperature of the device itself rises, causing a problem that the IC chip malfunctions or stops operating. As a result, a device using a conventional circuit board cannot perform its function normally and stably over a long period of time, and may cause a life-threatening accident especially in an in-vehicle device.

  The present invention has been completed to solve the above-mentioned problems of the prior art, and its purpose is to provide a resistor layer co-fired on the surface, a protective glass layer covering the resistor layer, and a heat transfer layer adjacent thereto. It is a circuit board with improved heat dissipation, and it is possible to prevent malfunction and stoppage of operation due to heat of the IC chip by closely bonding the thermal via and the Al housing and heat radiator that dissipate heat. An object of the present invention is to provide a circuit board capable of normalizing and stabilizing the functions of various electronic devices and electronic devices using the board over a long period of time.

A circuit board for mounting a semiconductor element according to the present invention comprises an insulating substrate in which a plurality of insulating layers are laminated and a wiring conductor is formed between the insulating layers, and a conductor layer formed on one main surface of the insulating substrate. A semiconductor element mounting portion, a heat transfer layer formed on the other main surface of the insulating substrate and including a glass component connected to the mounting portion via a through conductor, and the heat transfer layer on the other main surface In a circuit board for mounting a semiconductor element, comprising a resistor layer containing a glass component formed in an adjacent portion, and a protective glass layer covering the resistor layer, the heat transfer layer, the resistor layer, and the The protective glass layer is formed by co-firing, the softening point of the glass component contained in the heat transfer layer is T ₁ , the softening point of the glass component contained in the resistor layer is T ₂ , and the protective glass layer When T ₃ is the softening point of T ₁ > T ₃ > T ₂

In the circuit board for mounting a semiconductor element of the present invention, preferably, the difference between the T ₂ and the T ₃ and the difference between the T ₃ and the T ₁ are each 30 ° C. or more.

In the circuit board for mounting a semiconductor element of the present invention, preferably, the cumulative average particle diameter of the glass powder contained in the heat transfer layer is D ₁ , and the cumulative average particle diameter of the glass powder contained in the resistor layer is D ₂ , wherein the integration average particle size of the powder of the protective glass layer is taken as _{D 3,} characterized in that D _1, is D 2, _{D 3} is 1.4 to 10.0μm or less, respectively.

A method of manufacturing a circuit board for mounting a semiconductor element of the present invention is a method of manufacturing a circuit board for mounting a semiconductor element of the present invention,
(1) A plurality of ceramic green sheets each having a through-hole to be the through-conductor and formed with a wiring paste and a conductive paste pattern to be the mounting portion are laminated, and the through-hole is filled with a conductor paste and fired. Producing a ceramic multilayer substrate;
(2) A paste layer containing a glass component serving as the heat transfer layer is formed on the other main surface of the ceramic multilayer substrate so as to be in contact with the end surface of the through conductor by a thick film printing method, and the transfer of the other main surface is performed. After forming the paste layer containing the glass component to be the resistor layer on the portion adjacent to the thermal layer by the thick film printing method, the glass paste layer to be the protective glass layer is covered with the thick film printing method. And forming with
(3) A step of co-firing a paste layer containing a glass component serving as the heat transfer layer, a paste layer containing a glass component serving as the resistor layer, and a glass paste layer serving as the protective glass layer. It is characterized by.

  The circuit board according to the present invention is formed on the other main surface of the insulating substrate, and is connected to the mounting portion via the through conductor while being mounted on the other main surface of the insulating substrate. Because it comprises a heat transfer layer containing a glass component, a resistor layer containing a glass component formed at a site adjacent to the heat transfer layer on the other main surface, and a protective glass layer covering the resistor layer, Since the protective glass layer that prevents heat conduction does not exist between the through conductor as a thermal via and the external Al housing or heat radiator that dissipates heat, the heat generated from the semiconductor element can be efficiently dissipated to the outside. Can do.

  In addition, since the surface of the heat transfer layer bonded to the lower part of the through conductor can be protruded from the surface of the protective glass layer, the wiring conductor entrains air bubbles when the circuit board is bonded to the Al housing or heat radiator using grease. Without any problem, it is possible to satisfactorily join the heat transfer layer to the Al housing or the heat radiating body. As a result, it is possible to efficiently dissipate the heat generated from the semiconductor element.

Moreover, the resistor layer, the protective glass layer, and the heat transfer layer are formed by simultaneous firing, and the softening point of the glass component contained in the heat transfer layer is T ₁ , and the softening point of the glass component contained in the resistor layer is When T ₂ is T ₃ and the softening point of the protective glass layer is T ₃ , T ₁ > T ₃ > T ₂ , so that the heat transfer layer can be efficiently bonded to the circuit board in one baking step, and resistance Since the body layer and the protective glass layer are also fired at the same time, they can be integrally formed to obtain a strong bonding structure. Furthermore, even when multiple heat transfer layers are formed by thick film printing, the flatness of each heat transfer layer is stable, and when the circuit board is mounted on an Al housing or radiator, the heat transfer layer And a gap between the Al housing and the heat radiating body can be prevented.

In the circuit board for mounting a semiconductor element of the present invention, preferably, the difference between T ₁ and T ₃ and the difference between T ₃ and T ₂ are 30 ° C. or more, respectively, so that the protective glass layer flows into the resistor layer. It is possible to prevent the resistance value from increasing and the filler in the heat transfer layer from flowing into the protective glass layer and decreasing the insulation resistance value of the protective glass layer.

In the circuit board for mounting a semiconductor element of the present invention, preferably, the integrated average particle diameter of the glass powder contained in the heat transfer layer is D ₁ , the integrated average particle diameter of the glass powder contained in the resistor layer is D ₂ , the cumulative average particle size of the powder of the protective glass layer is taken as D _3, since the D _{1, D 2,} D ₃ is respectively 1.4μm or more, the surface energy of the glass powder is specifically increased, more No softening at low temperatures. Further, since each of D ₁ , D ₂ , and D _{3 of the} glass powder is 10.0 μm or less, it is uneven even when a 30 to 500 μm wide wiring generally formed on a ceramic wiring substrate is printed by a screen printing method. No wiring surface is obtained. The cumulative average particle diameter here indicates the particle diameter when the particle diameter of the glass powder is counted from the finer and the quantity reaches 50%. As a result, since the heat generated from the semiconductor element can be sufficiently dissipated, it is possible to manufacture a circuit board that can prevent problems such as a malfunction of the semiconductor element and a stoppage of operation due to a rise in the temperature of the operating semiconductor element itself. Various electronic devices and electronic devices using this circuit board can be operated normally and stably over a long period of time.

The method for manufacturing a circuit board for mounting a semiconductor element of the present invention includes:
(1) A ceramic multilayer substrate is formed by stacking a plurality of ceramic green sheets in which a through hole to be a through conductor is formed and a conductor paste pattern to be a wiring conductor and a mounting portion, respectively, and filling the through hole with a conductor paste and firing. A manufacturing process;
(2) A paste layer containing a glass component serving as a heat transfer layer is formed on the other main surface of the ceramic multilayer substrate so as to be in contact with the end surface of the through conductor, and is adjacent to the heat transfer layer on the other main surface. Forming a paste layer containing a glass component to be a resistor layer at a site by a thick film printing method, and then forming a glass paste layer to be a protective glass layer by covering the resistor layer by a thick film printing method;
(3) a step of co-firing a paste layer containing a glass component to be a heat transfer layer, a paste layer containing a glass component to be a resistor layer, and a glass paste layer to be a protective glass layer; Since there is a step of co-firing a paste layer containing a glass component to become, a paste layer containing a glass component to be a resistor layer and a glass paste layer to be a protective glass layer, the firing step is only once, This is a manufacturing method that can reduce energy consumption and follow the trend of environmental protection in the future. In addition, the resistor layer, the protective glass layer, and the heat transfer layer can be positioned without being affected by shrinkage deformation or dimensional change due to firing, and a manufacturing method capable of manufacturing a circuit board with high positional accuracy.

  Next, a circuit board for mounting a semiconductor device according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view showing an example of an embodiment of a circuit board according to the present invention. FIG. 2 is a cross-sectional view showing an example of a conventional circuit board. FIG. 3 is a cross-sectional view showing an example of an embodiment in which the circuit board of the present invention is mounted on an Al housing. 1 to 3, 1 is an insulating layer, 2 is a wiring conductor, 3 is a through conductor, 4 is a heat transfer layer, 5 is a resistor layer, 6 is a protective glass layer for protecting the resistor layer, and 7 is a semiconductor element. , 8 is an Al housing or a radiator.

A circuit board according to the present invention comprises a semiconductor element comprising a plurality of insulating layers 1 laminated and an insulating substrate having a wiring conductor 2 formed between the insulating layers 1 and a conductor layer formed on one main surface of the insulating substrate. 7, adjacent to the heat transfer layer 4 formed on the other main surface of the insulating substrate and including the glass component connected to the mount portion through the through conductor 3, and the heat transfer layer 4 on the other main surface. The resistor layer 5 containing the glass component formed in the part and the protective glass layer 6 covering the resistor layer 5 are provided, and the heat transfer layer 4, the resistor layer 5 and the protective glass layer 6 are simultaneously fired. When the softening point of the glass component contained in the heat transfer layer 4 is T ₁ , the softening point of the glass component contained in the resistor layer 5 is T ₂ , and the softening point of the protective glass layer 6 is T _3. T ₁ > T ₃ > T ₂ .

In the present invention, T ₁ is about 720 ° C., T ₂ is about 560 ° C., and T ₃ is about 630 ° C.

  In the present invention, the insulating layer 1 includes an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, a glass ceramic sintered body, and the like. It is an electrically insulating material made of ceramics.

The glass ceramic sintered body is composed of a glass component and a filler component. Examples of the glass component include SiO ₂ —B ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , and SiO ₂ —B. ₂ O ₃ —Al ₂ O ₃ —MO system (wherein M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ And M ² are the same or different and represent Ca, Sr, Mg, Ba or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O system (where M ¹ and M ² is the same as above), SiO ₂ —B ₂ O ₃ —M ³ ₂ O system (where M ³ represents Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ -M ³ ₂ O system (where M ³ is the same as above), Pb system gas Glass, Bi glass, and the like.

Examples of the filler component include a composite oxide of Al ₂ O ₃ , SiO ₂ , ZrO ₂ and an alkaline earth metal oxide, a composite oxide of TiO ₂ and an alkaline earth metal oxide, Al ₂ O _3. And composite oxides containing at least one selected from SiO ₂ (for example, spinel, mullite, cordierite) and the like.

  The wiring conductor 2 and the through conductor (thermal via) 3 are, for example, tungsten (W), molybdenum (Mo), gold (Au), silver (Ag), palladium (Pd), platinum (Pt), nickel (Ni), It consists of the metallized metal which has metal material powders, such as copper (Cu), as a main component. This metallized metal can be obtained by sintering a conductor paste. The metallized metal is combined with the firing shrinkage of the conductor paste and the firing shrinkage of the glass ceramic, and ensures the bonding strength with the insulating layer 1 made of a glass ceramic sintered body. Therefore, glass powder or ceramic powder may be added to the conductor paste, and the wiring conductor 2 and the through conductor 3 may have different types and amounts of glass powder and ceramic powder added.

The resistor layer 5 is connected to the wiring conductor 2 to adjust its resistance value, and includes ruthenium dioxide (RuO ₂ ), silver palladium (Ag—Pd) alloy, lanthanum bolite (LaB ₅ ), dioxide dioxide. Main component is tin (SnO ₂ ), copper nickel (Cu—Ni) alloy, etc., binder, SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, Bi ₂ O ₃ -SiO ₂ -based, ZnO-SiO ₂ -B ₂ O ₃ -based, SiO ₂ -B ₂ O ₃ -based glass are kneaded to form a paste, formed into a desired shape using a thick film printing method, and 50 to 150 in advance. Dry at ℃.

The protective glass layer 6 is composed of SiO ₂ —B ₂ O ₃ system, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ system, Bi ₂ O ₃ —SiO ₂ system, ZnO—SiO ₂ —B ₂ O ₃ system, SiO _{2 The} main component is _2- B ₂ O ₃ -based glass, which is kneaded with a binder to form a paste, is formed into a desired shape using a thick film printing method, and is dried in advance.

The heat transfer layer 4 is mainly composed of copper (Cu), silver (Ag), alumina (Al ₂ O ₃ ), diamond (C), etc., and includes a binder, a SiO ₂ —B ₂ O ₃ system, and SiO ₂ —B. ₂ O ₃ —Al ₂ O ₃ series, Bi ₂ O ₃ —SiO ₂ series, ZnO—SiO ₂ —B ₂ O ₃ series, SiO ₂ —B ₂ O ₃ series glass are kneaded to form a paste and thick film printing The desired shape is formed using a method.

  The resistor layer 5, the protective glass layer 6, and the heat transfer layer 4 are formed by simultaneous firing at about 850 ° C.

  Here, the following Table 1 shows the types of compositions of the glass components of the insulating substrate made of the glass ceramic sintered body constituting the circuit board of the present invention. Table 2 also shows an increase in the resistance value of the resistor layer 5 depending on the combination of the glass component compositions (using types A to L in Table 1) of the resistor layer 5 and the protective glass layer 6 formed on the circuit board of the present invention. The result confirmed about is shown. Table 3 also shows that the heat transfer layer 4 and the protective glass layer 6 formed on the circuit board of the present invention are transferred into the protective glass layer 6 by the combination of the glass component compositions (use types A to L in Table 1). The result of having confirmed whether the desired resistance value of the resistor layer 5 was favorable by the confirmation of the elution presence or absence of the filler in the heat layer 4, and the influence of the elution of the filler in the heat transfer layer 4 is shown.

  Table 4 shows the glass components of the heat transfer layer 4, the resistor layer 5, and the protective glass layer 6, measured and calculated by differential thermal analysis (DTA) for changes in the cumulative average particle size and softening temperature of the glass powder. It is. Table 5 shows the accumulated average particle diameter of the glass powder and the surface roughness after the screen printing for the glass components of the heat transfer layer 4, the resistor layer 5, and the protective glass layer 6, and the subsequent surface roughness. (Maximum height: Rmax) is measured.

In Table 3, the case where the change in the resistance value of the resistor layer 5 was 10% or less with respect to the desired resistance value was marked with ◯, and the case where it exceeded 10% was marked with x.

And the circuit board of this invention is produced as follows. First, a method for manufacturing a circuit board according to the present invention includes:
(1) A ceramic multilayer in which a plurality of ceramic green sheets each having a through hole to be a through conductor 3 and a wiring paste 2 and a conductive paste pattern to be a mounting portion are stacked, the conductive paste is filled in the through hole, and fired. Producing a substrate;
(2) A paste layer containing a glass component to be the heat transfer layer 4 is formed on the other main surface of the ceramic multilayer substrate so as to be in contact with the end surface of the through conductor 3 by a thick film printing method, and the heat transfer layer 4 on the other main surface After forming the paste layer containing the glass component that becomes the resistor layer 5 in the portion adjacent to the thick film printing method, the glass paste layer that covers the resistor layer 5 and becomes the protective glass layer 6 is formed by the thick film printing method. And a process of
(3) A step of co-firing a paste layer containing a glass component to be the heat transfer layer 4, a paste layer containing a glass component to be the resistor layer 5, and a glass paste layer to be the protective glass layer 6 It is.

  For example, when the insulating layer 1 is made of a glass ceramic sintered body, first, a desired organic binder, plasticizer, organic solvent, etc. are added to and mixed with raw material powders such as ceramic powder and glass powder to form a slurry. Is formed into a sheet shape by a conventionally known doctor blade method or calendar roll method to produce a green sheet. Also, a conductor paste is prepared by adding and mixing a desired organic solvent and solvent to a low melting point metal powder such as copper or silver.

  Next, through holes and wiring pattern-like grooves for forming interlayer through conductors and through conductors 3 are formed on the green sheet, for example, by punching, and the through holes are filled with a conductive paste, for example, by screen printing. Subsequently, a conductor paste is printed so that a predetermined circuit pattern is formed on the surface of each layer of the other wiring conductors 2. The green sheets on which these conductor pastes are printed are stacked, and if necessary, pressed at a temperature of 50 to 100 ° C. and a pressure of 3 to 200 MPa, and fired at a temperature of about 800 to 1000 ° C.

Furthermore, a thick film printing method is applied to the surface of the ceramic multilayer substrate to form a resistor layer 5 containing a glass component mainly composed of ruthenium dioxide (RuO ₂ ), silver palladium (Ag—Pd) alloy or the like in a desired shape. A paste layer is formed using and dried at 50 to 150 ° C. Thereafter, in order to form the protective glass layer 6 on the ceramic multilayer substrate on which the resistor layer 5 is formed, a glass paste mainly composed of glass is printed so as to cover the resistor layer 5 by using a thick film printing method. Form and dry at 50-150 ° C. Furthermore, a thick film printing method is used to paste a paste that becomes the heat transfer layer 4 containing a glass component mainly composed of copper (Cu), silver (Ag), alumina (Al ₂ O ₃ ), diamond (C) or the like into a desired shape. And baked at 500 to 900 ° C.

  Thereafter, nickel plating, palladium plating, gold plating, or the like may be applied to the surface of the wiring conductor 2 or the through conductor 3 exposed on the surface of the circuit board to prevent corrosion.

  The circuit board of the present invention manufactured as described above has a configuration in which the protective glass layer 6 that prevents heat conduction does not exist between the through conductor 3 and the external heat dissipation Al housing or the radiator 8. Therefore, the heat generated from the semiconductor element 7 can be efficiently dissipated.

  Further, since the heat transfer layer 4 bonded to the lower end surface of the through conductor 3 can be convex with respect to the surface of the protective glass layer 6, the through conductor is used when bonding to the Al housing or the radiator 8 using grease. 3 The lower part does not entrap air bubbles, and the heat transfer layer 4 and the Al housing or the heat radiating body 8 can be joined well, and as a result, the heat generated from the semiconductor element 7 can be efficiently dissipated. It becomes.

Also, is the resistor layer 5 and the protective glass layer 6 and the heat transfer layer 4 is co-fired, the softening point of the glass component contained in the heat transfer layer T _1, the softening point of the glass component contained in the resistive layer T _2. When T ₁ > T ₃ > T ₂ when the softening point of the protective glass layer is T ₃ , the heat transfer layer 4 can be efficiently joined in one firing step, and the resistor layer 5 Further, the protective glass layer 6 and the heat transfer layer 4 are integrally formed by simultaneous firing, so that a strong bonding structure can be obtained. Further, even when the plurality of heat transfer layers 4 are formed by the thick film printing method, the flatness of each heat transfer layer 4 is stable, and when the circuit board is mounted on an Al housing or a heat radiator, the heat transfer is performed. It is possible to prevent a gap from being generated between the heat layer 4 and the Al housing or the heat radiator.

In the circuit board of the present invention, the difference between T ₁ and T ₃ and the difference between T ₃ and T ₂ are each preferably 30 ° C. or more. In this case, the protective glass layer 6 flows into the resistor layer 5. Therefore, the resistance value is not increased, and the filler in the heat transfer layer 4 does not flow into the protective glass layer 6 to reduce the insulation resistance value of the protective glass layer 6.

On the other hand, when the difference between T ₂ and T ₃ is less than 30 ° C., the protective glass layer 6 melts in a very sparse state where the glass in the resistor layer 5 is powdery. Thereby, since the protective glass layer 6 melt | dissolves between the metal particles contained in the resistor layer 5, the resistance value of the resistor layer 5 will be raised. Moreover, when there is much penetration amount, the electroconductivity of the resistor layer 5 may deteriorate and it may become close to an insulator.

When the difference between T ₃ and T ₁ is less than 30 ° C., the glass in the heat transfer layer 4 is melted in a very sparse state where the glass in the protective glass layer 6 is powdery. Thereby, since the glass in the heat-transfer layer 4 melts in the protective glass layer 6 together with the filler, the insulation resistance value of the protective glass layer 6 for maintaining insulation as the protective layer is lowered. Moreover, when there is much melt | dissolution amount, it becomes easy to generate | occur | produce an electrical short circuit between the wiring conductors 2 of the circuit board surface protected with the protective glass layer 6. FIG.

In the circuit board of the present invention, preferably, the difference between T ₂ and T ₃ and the difference between T ₃ and T ₁ are 30 ° C. or more, respectively. 7 can sufficiently dissipate heat, so that it is possible to prevent a problem that the temperature of the operating semiconductor element 7 itself rises to cause malfunction or stoppage of operation.

Generally, the cumulative average particle size of the powder glass used for such a circuit board is about 1.0 to 20.0 μm. However, in the circuit board of the present invention, D ₁ , D ₂ , D ₃ are preferable. Is 1.4 μm or more, the surface energy of the glass powder is specifically increased, and T ₁ , T ₂ , T ₃ become lower temperature. As a result, the protective glass layer 6 becomes the resistor layer 5. The resistance value is not increased by flowing in, and the filler in the heat transfer layer 4 does not flow into the protective glass layer 6 and the insulation resistance value of the protective glass layer 6 is not reduced.

In addition, since D ₁ , D ₂ , and D _{3 of} the glass powder are each 10.0 μm or less, even when a 30 to 500 μm wide wiring generally formed on a ceramic wiring substrate is printed by a screen printing method. A wiring surface without irregularities can be obtained. As a result, it is possible to operate electronic devices and electronic devices using the circuit board of the present invention normally and stably over a long period of time.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described method for manufacturing a circuit board, the case where the resistor layer 5, the protective glass layer 6, and the heat transfer layer 4 are formed on the same surface of the circuit board has been described. 5. The manufacturing method of the present invention can also be applied to the case where the protective glass layer 6 is on the opposite side of the protective glass layer 6.

It is sectional drawing which shows an example of embodiment of the circuit board for semiconductor element mounting of this invention. It is sectional drawing which shows an example of embodiment of the conventional circuit board for semiconductor element mounting. It is sectional drawing which shows an example of embodiment when the circuit board for semiconductor element mounting of this invention is mounted in Al housing.

Explanation of symbols

1: Insulating layer 2: Wiring conductor 3: Through conductor 4: Heat transfer layer 5: Resistor layer 6: Protective glass layer 7: Semiconductor element

Claims (4)

An insulating substrate having a plurality of insulating layers stacked and wiring conductors formed between the insulating layers; a semiconductor element mounting portion comprising a conductor layer formed on one main surface of the insulating substrate; and A heat transfer layer including a glass component formed on the other main surface and connected to the mounting portion via a through conductor, and a glass component formed on a portion adjacent to the heat transfer layer on the other main surface is included. In a circuit board for mounting a semiconductor element comprising a resistor layer and a protective glass layer covering the resistor layer, the heat transfer layer, the resistor layer, and the protective glass layer are formed by simultaneous firing. and, the softening point of the glass component contained in the heat transfer layer T _1, the softening point of the glass component contained in the resistive layer T _2, the softening point of the protective glass layer is taken as T _3, T ₁ > T ₃ > T ₂ Circuit board for mounting conductor elements. _{2. The} circuit board for mounting a semiconductor element according to claim ₁ , wherein a difference between the T ₁ and the T ₃ and a difference between the T ₃ and the T ₂ are each 30 ° C. or more. The accumulated average particle diameter of the glass powder contained in the heat transfer layer is D ₁ , the accumulated average particle diameter of the glass powder contained in the resistor layer is D ₂ , and the accumulated average particle diameter of the powder of the protective glass layer is D _{3. 2. The} circuit board for mounting a semiconductor element according to claim 1, wherein D ₁ , D ₂ , and D ₃ are 1.4 to 10.0 μm, respectively. A method for manufacturing a circuit board for mounting a semiconductor element according to claim 1 or 2,
(1) A plurality of ceramic green sheets each having a through-hole to be the through-conductor and formed with a wiring paste and a conductive paste pattern to be the mounting portion are laminated, and the through-hole is filled with a conductor paste and fired. Producing a ceramic multilayer substrate;
(2) A paste layer containing a glass component serving as the heat transfer layer is formed on the other main surface of the ceramic multilayer substrate so as to be in contact with the end surface of the through conductor by a thick film printing method, and the transfer of the other main surface is performed. After forming the paste layer containing the glass component to be the resistor layer on the portion adjacent to the thermal layer by the thick film printing method, the glass paste layer to be the protective glass layer is covered with the thick film printing method. And forming with
(3) A step of co-firing a paste layer containing a glass component serving as the heat transfer layer, a paste layer containing a glass component serving as the resistor layer, and a glass paste layer serving as the protective glass layer. A method of manufacturing a circuit board for mounting a semiconductor element, comprising:

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