JPH0470124B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a method for manufacturing a ceramic multilayer wiring circuit board, and particularly to a method for manufacturing a ceramic multilayer wiring circuit board, and in particular, a method for manufacturing a high-precision ceramic circuit board for attaching pins for inputting and outputting electrical signals, and for mounting semiconductor components to configure a functional module. It is suitable for substrates. [Background of the Invention] In recent years, ceramic substrates with multilayer wiring have been used as substrates for mounting semiconductor components at high density. Ceramic insulators used in these devices are often sintered bodies containing alumina (Al ₂ O ₃ ) as a main component. Conventional ceramic multilayer wiring circuit boards are made by applying internal wiring and conductor connections between layers to green sheets made by bonding ceramic powder with resin, laminating and pressing a large number of sheets, and then firing them in a furnace without applying pressure. was. The biggest drawback of this manufacturing method is that shrinkage deformation and warping occur when the green sheet laminate is fired. Firing shrinkage fluctuates due to slight temperature changes in the furnace, and especially in high-density wiring boards, this slight variation can cause misalignment in the connections of semiconductor components and pin terminals for inputting and outputting electrical signals. will occur. Furthermore, warping during firing may cause connection failures when semiconductor components are mounted. [Object of the Invention] An object of the present invention is to provide a ceramic multilayer wiring circuit board for connecting pins for inputting and outputting electrical signals and semiconductor components to a ceramic board with high precision, and a method for manufacturing the same. [Summary of the Invention] To summarize the present invention, there is provided a method for manufacturing a ceramic multilayer wiring circuit board in which a ceramic insulating material and a conductive material are laminated in multiple layers, and the resulting laminate is fired. A heating process to remove the resin within a temperature range that does not cause dimensional changes,
The present invention also relates to a method for manufacturing a ceramic multilayer wiring circuit board, comprising the step of firing the laminate by applying a load in the thickness direction within a range that does not substantially cause dimensional change in the planar direction. The method for manufacturing a ceramic multilayer wiring circuit board according to the present invention is characterized in that firing is performed under a state in which uniaxial pressure is applied perpendicularly to the surface to which pins for inputting and outputting electric signals and semiconductor components are connected. Ceramic insulation sintered bodies normally used for ceramic multilayer wiring circuit boards contain 2 to 30% as a sintering aid.
(by weight) of glass components. Therefore, when the glass powder interposed between the ceramic powders reaches a temperature higher than the softening point of the glass, the entire part softens almost simultaneously and flows to surround the ceramic powders, forming a homogeneous sintered body. Since so-called liquid phase sintering is performed, sintering can be performed at a relatively low temperature of 1400 to 1600°C in a short time. As can be seen, the main factor determining the progress of sintering is not the ceramic main material, but the glass component as a sintering aid, and its softening point. Conversely, even if ceramic main materials are mixed in some parts, if glass components of the same composition are used as sintering aids, uniform sintering can be achieved because the same liquid phase sintering is performed. As a manufacturing method for combining insulating layers made of different ceramic main materials, the most suitable method is to first form the insulating materials into green sheets, process them into green sheets, and then laminate them together and sinter them. In forming this green sheet, in addition to the ceramic main material and the above-mentioned sintering aid of the glass component, binders, plasticizers, solvents, etc. are used. For example, binders include synthetic resins such as polyvinyl alcohol, polyvinyl butyral, and polymethacrylic acid; plasticizers include dioctyl phthalate and butyl phthalyl glycolate; and solvents include methanol, trichlene, toluene, tetrachlorethylene, and butyl alcohol. etc. These are weighed and mixed to form a slurry. Next, this slurry is applied onto a support such as a silicon-treated polyester film, adjusted to a desired thickness using a doctor bud, etc., and then dried to form a green sheet. This green sheet is provided with through holes for connecting conductor circuits, and molybdenum or tungsten paste as conductor circuits is printed inside the through holes and in accordance with the circuit pattern. A plurality of green sheets whose main component is ceramic processed in this way are laminated together into a desired configuration and fired in a neutral or reducing atmosphere. The reason why a reducing atmosphere is required is to prevent molybdenum, tungsten, or copper used in the conductor circuit from being oxidized and volatilized.
However, in order to oxidize and disperse the binder or plasticizer contained in the green sheet, it is desirable to include moisture as an oxidation source in the atmosphere during the firing period. When firing in a reducing atmosphere, if a glass powder containing an oxide that is easily reduced, such as lead oxide or titanium oxide, is used, the insulation of the sintered body, that is, the substrate, may deteriorate. Therefore, it is preferable that the glass powder is substantially free of such compounds. However, when gold or silver is used as the conductor material, firing in the atmosphere is possible. Conventionally, when firing green sheet laminates, a large number of them were placed on a setter and fired without pressure. In this case, firing shrinkage occurs in the width direction and thickness direction, and the firing shrinkage rate fluctuates due to slight temperature differences within the furnace. Due to variations in the metallization pattern used to mount the device, positional deviations occur and connection failures occur. Furthermore, since firing is performed without pressure, the substrate often warps due to the flow of atmospheric gas and firing conditions. This is due to the difference between the ambient temperature and the setter temperature, and the difference in firing shrinkage rate and thermal expansion coefficient due to different materials, such as ceramic materials and conductive materials, ceramic materials with different compositions, etc. Therefore, in order to eliminate misalignment and warpage of the metallized pattern due to these causes, a load is applied in the thickness direction during firing, and the width direction (plane direction) is
This eliminates firing shrinkage and prevents warping. The thus fired ceramic multilayer wiring circuit board is plated with nickel or the like, and then pins or leads made of Kovar or the like are brazed with silver solder. Then, semiconductor components are mounted on it to form a single functional module. [Embodiments of the Invention] Examples of the present invention will be shown below. In each of the following examples, "part" means part by weight, and "%" means percent by weight.
means. Example 1 Mullite powder with an average particle size of 5 μm or less (3Al ₂ O ₃
2SiO ₂ ) 70 parts, SiO ₂ :Al ₂ O ₃ :MgO=51.3:
Add 5.9 parts of polyvinyl butyral to 30 parts of glass powder material having a composition of 34.9:13.8 (weight ratio) in a ball mill and dry mix for 3 hours. Furthermore, 1.9 parts of butyl phthalyl glycolate, 23 parts of trichlorethylene, 6 parts of tetrachloroethylene, and 8 parts of butyl alcohol were added and wet mixed for 20 hours to prepare a slurry. Air bubbles are removed from the slurry by vacuum degassing. The slurry is then applied to a thickness of 0.25 mm on a silicone-coated polyester film support using a doctor blade and dried in an oven to produce a mullite-glass green sheet. After cutting this green sheet into a size of 200 x 200 mm, through holes are punched at predetermined positions using a punch method. Furthermore, a conductor paste of molybdenum powder: ethyl cellulose: polyvinyl butyral: butyl carbitol acetate: dibenzylidene-D-sorbitol = 88:2:0.7:21:2 (weight ratio) was printed according to a predetermined circuit pattern by screen printing. do. The semiconductor paste was also filled into the through holes for connection between layers.
Next, five green sheets were laminated according to the positions of the guide holes, and the sheets were laminated under pressure at a temperature of 90°C. Next, put the stacked green sheets into a firing furnace,
Firing was performed under a load in a nitrogen atmosphere containing 3 to 7% by volume of hydrogen and a trace amount of water vapor. 1200
℃, the temperature was increased at a rate of 100℃ or less per hour without applying any pressure, the resin content was removed, and then a pressure of 30Kg/cm ² was applied, and the maximum temperature was maintained at 1540℃ for 1 hour for firing. This board has a metallized surface for connecting leads used for inputting and outputting electrical signals and a surface on which semiconductor components are mounted, which are smooth and free from warp, and have high precision according to desired dimensions. This is because the pressure was applied in the thickness direction of the substrate, so there was no firing shrinkage in the plane direction (width direction), and firing shrinkage occurred only in the thickness direction. After electroless nickel plating was applied to this substrate, a Kovar lead was connected to the back conductor layer using a gold-tin alloy in a conventional manner using a carbon jig. Furthermore, semiconductor components were connected to the surface conductor layer with solder. There was no deviation in the connection position between the Kovar lead and the semiconductor component, and the connection surface was smooth, so no connection failure was observed. FIG. 1 is a cross-sectional view of the layer structure of a ceramic multilayer wiring circuit board according to Embodiment 1 of the present invention and a functional module using the board. In Figure 1, reference numeral 1
2 means a sintered body mainly composed of mullite, 2 means a molybdenum internal wiring conductor, 3 means a ceramic multilayer wiring circuit board, 4 means Kovar lead, 5 means solder, and 6 means a chip carrier. Example 2 Alumina powder (Al ₂ O ₃ ) passing through 325 mesh 90
10 parts of a glass powder material having a composition of SiO ₂ :Al ₂ O ₃ :MgO=51.3:34.9:13.8 (weight ratio) was put into a ball mill and dry mixed for an hour. Furthermore, 5.9 parts of polyvinyl butyral, 2.4 parts of dioctyl phthalate, 23 parts of trichloroethylene, 9 parts of perchlorethylene and 6 parts of butyl alcohol are added and mixed for 3 hours to prepare a slurry. Air bubbles are removed from the slurry by vacuum degassing. The slurry is then transferred onto a polyester film support using a doctor blade.
It is applied to a thickness of 0.3 mm and dried in an oven to create an alumina-glass green sheet. After cutting this green sheet into a size of 200 x 200 mm, through holes are punched at predetermined positions using a punch method. In addition, tungsten powder: nitrocellulose: ethyl cellulose: polyvinyl butyral:
A conductor paste of trichlorethylene=100:3:1:2:23 (weight ratio) is printed according to a predetermined circuit pattern by screen printing. The conductive paste was also filled into the through holes for connection between layers. Eleven of these green sheets were laminated with the guide holes aligned, and the sheets were laminated under pressure at a temperature of 90°C.
Next, the laminated green sheets were placed in a firing furnace and fired under a load in a nitrogen atmosphere containing 3 to 7% by volume of hydrogen and a trace amount of water vapor.
Up to 1200℃, the atmosphere must contain a trace amount of water vapor.
without applying any load at a heating rate of 100℃ or less per hour.
After removing the resin component, a pressure of 50 kg/cm ² was applied and the product was fired at a maximum temperature of 1600° C. for 1 hour.
Because pressure was applied to this substrate in the thickness direction, there was no firing shrinkage in the width direction (plane direction), and there was firing shrinkage only in the thickness direction. For this reason, the metallized surface for connecting pins used for inputting and outputting electrical signals and the surface for mounting semiconductor components are smooth and free from warping.
High precision according to desired dimensions. After electroless nickel plating was applied to this substrate, Kovar pins were connected to the back conductor layer using silver solder using a conventional method using a carbon jig. In addition, a silicon semiconductor element was mounted face-down on the surface layer and connected directly to the substrate using solder. There was no deviation in the connection position between the Kovar pin and the silicon semiconductor element, and the connection surface was smooth, so no connection failure was observed. FIG. 2 is a cross-sectional view of the layer structure of a ceramic multilayer wiring circuit board according to a second embodiment of the present invention and a functional module using the board. In Figure 2, reference numeral 1
1 is a sintered body mainly made of alumina, 12 is a tungsten internal wiring conductor, 13 is a ceramic multilayer wiring circuit board, 14 is a Kovar pin, 15 is solder, 1
6 means a silicon semiconductor element. Example 3 60 parts of 325 mesh silica powder (SiO ₂ ),
40 parts of a glass powder material having a composition of SiO ₂ :Al ₂ O ₃ :MgO:CaO=55:30:9:6 (weight ratio) is placed in a ball mill and dry mixed for 6 hours. Further, 5.9 parts of polyvinyl butyral were added and mixed for 1 hour, and then 2.3 parts of butyl phthalyl glycolate, 23 parts of trichlorethylene, 6 parts of tetrachlorethylene, and 8 parts of butyl alcohol were added and mixed for 24 hours to prepare a slurry. Air bubbles are removed from the slurry by vacuum degassing. Next, the slurry is applied onto a polyester film support to a thickness of 0.25 mm using a doctor blade and dried in an oven to produce a silica-glass green sheet. After cutting this green sheet to a size of 200 x 200 mm, through holes are punched at predetermined positions using a punch method. Furthermore, molybdenum powder: ethyl cellulose: polyvinyl butyral: butyl carbitol acetate:
Dibenzylidene-D-sorbitol = 88:2:
A conductor paste of 0.7:21:2 (weight ratio) is printed according to a predetermined circuit pattern by screen printing. The conductive paste was also filled into the through holes for connection between layers. Next, stack 7 green sheets with the guide holes aligned, and heat to 90°C.
Pressure was applied and laminated. Next, the laminated green sheets were placed in a firing furnace and fired under a load in a nitrogen atmosphere containing 3 to 7% by volume of hydrogen and a trace amount of water vapor. Up to 1200℃, the resin content is removed by heating at a rate of 100℃ or less per hour without applying pressure, and then a pressure of 25Kg/cm ² is applied to reach the maximum temperature.
It was fired by holding it at 1500°C for 1 hour. This board is
Since pressure was applied in the thickness direction, there was no firing shrinkage in the width direction (plane direction), and firing shrinkage occurred only in the thickness direction. Therefore, the metallized surface for connecting pins used for inputting and outputting electrical signals and the surface on which semiconductor components are mounted are smooth and free from warp, and are highly accurate to desired dimensions. After electroless nickel plating was applied to this substrate, Kovar pins were connected to the back conductor layer using a gold-tin alloy in a conventional manner using a carbon jig. In addition, a silicon semiconductor element was mounted face-down on the surface layer and connected directly to the substrate using solder. There was no deviation in the connection position between the Kovar pin and the silicon semiconductor element, and the connection surface was smooth, so no connection failure was observed. The silica used here is quartz, quartz glass, cristobalite, and tridymite, and contains at least one type of polymorphic silica. Example 4 At least two types of mullite glass, alumina glass, and silica glass green sheets prepared in Examples 1 to 3 above are used. After cutting these green sheets into a size of 200 x 200 mm, through holes are punched at predetermined positions using a punch method. Furthermore, the molybdenum paste or tungsten paste used in Examples 1 to 3 above is printed into a predetermined circuit pattern by screen printing. The conductive paste was also filled into the through holes for connection between layers. Alumina-glass green sheets are used for the insulating layer in contact with the metallized layer for connecting pins used for inputting and outputting electrical signals, and the insulating layer in contact with the metallized layer for mounting semiconductor components, and for the internal wiring layer. A mullite-glass green sheet or a silica-glass green sheet was used for the other insulating layer in contact with the above. Five of these green sheets were laminated with the guide holes aligned, and the sheets were laminated under pressure at a temperature of 90°C. Next, the laminated green sheets were placed in a firing furnace and fired under a load in a nitrogen atmosphere containing 3 to 7% by volume of hydrogen and a trace amount of water vapor. Up to 1200℃, the temperature is raised at a rate of 100℃ or less per hour without applying pressure, the resin content is removed, and then the temperature is increased for 30 minutes.
A pressure of Kg/cm ² was applied, and the maximum temperature was maintained at 1560° C. for 1 hour for firing. In this way, the two insulating layers exposed on the surface are made of alumina-glass sintered material, and the other insulating layers are made of alumina-glass-based or silica-glass sintered material, numbering five insulating layers. A ceramic multilayer wiring circuit board having six layers was manufactured. Since this substrate was subjected to pressure in the thickness direction, there was no firing shrinkage in the width direction (plane direction), and firing shrinkage occurred only in the thickness direction. Therefore, the metallized surface for connecting leads used for inputting and outputting electrical signals and the surface on which semiconductor components are mounted are smooth and free from warp, and are highly accurate in accordance with desired dimensions. Normally, when different materials are laminated and fired without pressure, warping occurs due to differences in firing shrinkage and thermal expansion coefficients, but in this example, the firing was done under load. Because different materials were used for the substrate, there was no warping of the board. The bonding between each layer of this substrate was good, and after electroless nickel plating, Kovar leads were connected to the back conductor layer with silver solder in the usual manner using a carbon jig. In addition, a chip carrier made of ceramic containing alumina as a main component was connected to the surface conductor layer with solder. The tensile strength of the lead was 1 kg/pin or more. This value was almost the same as that of a substrate whose entire layer was made of a sintered body mainly composed of alumina, and was strong enough to withstand actual use. Additionally, the chip carrier's soldered joints did not break during more than 3,000 temperature cycles from -65°C to +150°C. This value was almost the same as that of a board whose entire layer was made of a sintered body whose main component was alumina, and the strength was sufficient to guarantee a sufficient connection life even under severe usage conditions. On the other hand, the signal propagation delay time into the internal wiring circuit is 7.7 ns/m when an insulator whose main component is mullite is used for the internal insulating layer; When an insulator was used, it was 7.0 ns/m. These values correspond to the dielectric constant of the insulating layer. The dielectric constant of an insulator whose main component is mullite is
5.5, and an insulator whose main component is silica is 4.5. In addition, a substrate whose entire layer is made of a sintered body whose main component is alumina has a dielectric constant of approximately 9.5.
Since the signal propagation delay time is 10.2 ns/m, the signal propagation delay time was reduced to 75-68% in this example. Example 5 Alumina or mullite or silica powder: 70 parts Glass powder (composition shown in Table 1): 30 parts Conductor paste: 100 parts copper powder 3 parts nitrocellulose 1 part ethyl cellulose 2 parts polyvinyl butyral 2 parts trichloroethylene 23 parts Thickness of green sheet :0.25mm Examples 1 to 4 except for the above changes
A green sheet laminate was produced in the same manner as described above.

【table】

〔Effect of the invention〕

According to the present invention, since a load is applied in the thickness direction during firing, there is no firing shrinkage in the width direction (plane direction), so the connection positions of pins (leads) and silicon semiconductor elements (semiconductor parts) to the substrate can be adjusted. There is no deviation at all, and the connection surface is smooth, so no connection defects are observed.

[Brief explanation of the drawing]

FIG. 1 shows the layer structure of a ceramic multilayer wiring circuit board according to Embodiment 1 of the present invention and a cross-sectional view of a functional module using the substrate, and FIG. 2 shows the layer structure of a ceramic multilayer wiring circuit board according to Embodiment 2 of the present invention. , is a cross-sectional view of a functional module using the substrate. 1...Sintered body mainly made of mullite, 2...Molybdenum internal wiring conductor, 3, 13...Ceramic multilayer wiring circuit board, 4...Kovar lead, 5, 15...Solder, 6...Chip carrier, 11...Mainly made of alumina Sintered body, 12... Tungsten internal wiring conductor, 14... Kovar pin, 16... Silicon semiconductor element.

Claims (1)

[Claims] 1. A method for manufacturing a ceramic multilayer wiring circuit board in which ceramic insulating material and conductive material are laminated in multiple layers and the resulting laminate is fired, wherein the laminate is heated with resin within a temperature range that does not substantially cause dimensional change. and a step of firing the laminate by applying a load in the thickness direction within a range where the laminate does not substantially change its dimension in the planar direction. Substrate manufacturing method.