JP3950950B2 - Manufacturing method of ceramic wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the electrode of electronic parts cannot be connected to a metallized wiring layer appropriately due to occurrence of scratches and adhesion of foreign objects in the metallized wiring layer. SOLUTION: In this ceramic wiring board, a metallized wiring layer 2 where the electrode of electronic parts 3 is connected via conductive connection members 7 and 8 is deposited onto the upper and lower surfaces of a ceramic substrate 1 having nearly flat upper and lower surfaces, and at the same time a thick-film layer 9 that is thicker than the metallized wiring layer 2 being deposited on the surface is deposited, at least, at one of the upper and lower surfaces while being arranged to surround the center of the surface, at least, by three points on the thick-film layer 9. Placement is made with the side of the thick-film layer 9 facing down, scratches and adhesion of foreign objects to the metallized wiring layer 2 can be prevented.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic wiring board, and more particularly to a ceramic wiring board in which metallized wiring layers to which electrodes of electronic components are respectively attached are attached to upper and lower surfaces of a flat ceramic substrate. It is.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, ceramic wiring boards are used as wiring boards for mounting electronic components such as semiconductor integrated circuit elements, for example, because they are excellent in electrical insulation and heat resistance and enable high-density wiring. In such a ceramic wiring board, there is known a ceramic wiring board in which metallized wiring layers are deposited on both upper and lower surfaces of a flat ceramic substrate in order to increase the mounting density of electronic components. In this manner, the ceramic wiring board having the metallized wiring layers deposited on both the upper and lower surfaces of the ceramic substrate has electronic components mounted on the upper and lower surfaces of the ceramic substrate, and the electrodes of the electronic components mounted on the surface and the surface of the surface. By connecting the metallized wiring layer via a conductive connecting member such as a bonding wire or a solder bump, the electronic components are mounted on both upper and lower surfaces.
[0003]
In such a ceramic wiring board, the metallized wiring layer is prevented from being oxidized and corroded, and the electrical connection between the electronic component and the metallized wiring layer through the conductive connecting member is made favorable. Normally, a plated metal layer composed of a nickel plating layer and a gold plating layer is sequentially deposited on the surface of the metallized wiring layer.
[0004]
In addition, this ceramic wiring board is configured by placing a flat ceramic green sheet laminate on which metalized paste for a metallized wiring layer is applied in a predetermined pattern on both upper and lower surfaces on a flat base plate for firing. Is manufactured by baking at a high temperature.
[0005]
[Problems to be solved by the invention]
However, according to this conventional ceramic wiring board, since the metallized wiring layers are attached to the upper and lower surfaces of the flat ceramic substrate, the ceramic wiring board is placed on a tray for transportation or storage, for example. Then, the metallized wiring layer on the side in contact with the mounting surface such as a tray is rubbed against the mounting surface, and the surface of the metallized wiring layer including the plated metal layer is scratched or foreign matter from the mounting surface adheres. It is easy to end up. Alternatively, when this conventional ceramic wiring board is manufactured, the metalized paste for the metalized wiring layer is printed and applied on both the upper and lower surfaces of the ceramic green sheet laminate, so that it is placed on the base plate for firing. In some cases, the metallized paste and the base plate were directly rubbed and scratched on the metallized wiring layer. If there are scratches or foreign objects on the metallized wiring layer in this way, electronic components are mounted on both the upper and lower surfaces of the ceramic wiring board and the electrodes of these electronic components are connected to the metallized wiring layer via a conductive connection member. However, there is a problem in that the two are not connected well, and thus the mounted electronic component may not be operated normally.
[0006]
The present invention has been devised in view of such conventional problems. The object of the present invention is to prevent the occurrence of scratches and foreign matter adhesion on the metallized wiring layers deposited on the upper and lower surfaces of the ceramic substrate. When electronic components are mounted on both the upper and lower surfaces of the substrate and the electrodes of these electronic components are connected to the metallized wiring layer via the conductive connection member, the electrodes of the electronic component and the metallized wiring layer are interposed via the conductive connection member. It is an object of the present invention to provide a ceramic wiring board that can be connected well and can always operate a mounted electronic component normally.
[0007]
[Means for Solving the Problems]
The method for manufacturing a ceramic wiring board according to the present invention includes depositing a metallized wiring layer in which electrodes of an electronic component are respectively connected to the upper and lower surfaces of a ceramic substrate having substantially flat upper and lower surfaces through a conductive connecting member, at least one of the upper and lower surfaces, rather thick than the metallized wiring layer deposited on said surface, and a thick film layer has thin than electronic components mounted on said surface, at least 3 on the thick film layer A method of manufacturing a ceramic wiring board, which is disposed so as to surround the center of the surface at a point, and the ceramic green sheet laminate to be the ceramic wiring board is attached to the base plate for firing on the thick film It is characterized by being fired in a state of being placed with the layer side down.
Further, the thick film layer is provided in an outer peripheral region of the ceramic wiring board having a rectangular shape in plan view and an inner region from the outer peripheral region.
The electronic device according to the present invention is characterized in that an electronic component is mounted on the ceramic wiring board obtained by the above manufacturing method.
[0008]
According to the ceramic wiring board of the present invention, a thick film layer thicker than the metallized wiring layer is disposed on at least one of the upper and lower surfaces of the ceramic substrate so as to surround the center of the surface at at least three of them. Therefore, when the ceramic wiring board is placed on a tray or the like, or when the ceramic green sheet laminate for the ceramic wiring board is placed on the baking base plate when the ceramic wiring board is manufactured, By placing the film layer side down, it is possible to prevent the metallized wiring layer deposited on this surface from rubbing against the placement surface.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a ceramic wiring board according to the present invention, wherein 1 is a ceramic substrate and 2 is a metallized wiring layer.
[0010]
The ceramic substrate 1 is made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, a silicon nitride sintered body, or a glass-ceramic. It is a substantially rectangular flat plate having a flat top and bottom surface with a side length of about 10 to 200 mm and a thickness of about 1 to 10 mm. The ceramic substrate 1 functions as a support member for supporting the electronic component, and a plurality of mounting portions for mounting the electronic component are formed at the center of the upper and lower surfaces, and these mounting portions are provided with a semiconductor. Electronic parts 3 such as integrated circuit elements are mounted.
[0011]
If such a ceramic substrate 1 is made of, for example, an aluminum oxide sintered body, an organic binder, solvent, plasticizer, and dispersion suitable for ceramic raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide are used. Add and mix the agent to make a mud-like shape, and prepare a plurality of ceramic green sheets by adopting the conventional doctor blade method to make a sheet-like shape, then suitable for these ceramic green sheets The metallized paste for the metallized wiring layer 2, the metallized via pillar 4, the metallized die attach layer 5, the metallized seal layer 6 and the thick film paste for the thick film layer 9, which will be described later, are printed and applied, and these ceramics Stack green sheets up and down to obtain a ceramic green sheet laminate Thereafter, this ceramic green sheet laminate is mounted on a firing base plate with the surface coated with the thick film paste for the thick film layer 9 facing down, and is fired at a temperature of about 1600 ° C. .
[0012]
Further, a plurality of metallized conductors such as a metallized wiring layer 2, a metallized via pillar 4, a metallized die attach layer 5, and a metallized seal layer 6 made of metal powder metallized such as tungsten, molybdenum, copper, or silver are fixed to the ceramic substrate 1. Has been.
[0013]
The metallized wiring layer 2 has a thickness of about 10 to 20 μm and is arranged in a number of patterns on the upper and lower surfaces and inside of the ceramic substrate 1. Each pattern is formed by metallized via pillars 4 provided inside the ceramic substrate 1. The predetermined ones are electrically connected to each other so as to be electrically derived from the mounting portion of the ceramic substrate 1 or its peripheral portion to the outer peripheral portion of the lower surface. These metallized wiring layers 2 and metallized via pillars 4 function as conductive paths for electrically connecting electronic components 3 mounted on each mounting portion of the ceramic substrate 1 to each other and electrically connecting to the outside. Then, the electrode of the electronic component 3 is electrically connected to the mounting portion of the metallized wiring layer 2 or its peripheral portion via a conductive connecting member such as a bonding wire 7 or a solder bump 8, and the ceramic of the metallized wiring layer 2. For example, a socket terminal connected to an external electric circuit board is electrically connected to a portion led out to the outer peripheral portion of the lower surface of the base 1.
[0014]
Further, the metallized die attach layer 5 is attached to each mounting part on the upper surface of the ceramic substrate 1 so as to have substantially the same thickness as the metallized wiring layer 2 applied to this surface. It functions as a base metal for mounting the electronic component 3 on. The electronic component 3 mounted on the upper surface of the ceramic substrate 1 is bonded to the metallized die attach layer 5 via a conductive bonding material such as a gold-silicon brazing material. In this example, the metallized die attach layer 5 is not attached to the mounting portion on the lower surface of the ceramic substrate 1, and the electronic component 3 mounted on the lower surface is fixed by the bumps 8.
[0015]
Further, the metallized seal layer 6 is applied to the outer peripheral portion of the upper surface of the ceramic substrate 1 in a frame shape with substantially the same thickness as the metallized wiring layer 2 applied to this surface. It functions as a base metal for joining the bowl-shaped lids that do not. And the electronic component 3 mounted on the upper surface of the ceramic base | substrate 1 is airtightly sealed by joining a bowl-shaped cover body to this metallized seal layer 6 via the sealing material which consists of gold-tin alloys, for example. . In this example, the metallized seal layer 6 is not attached to the lower surface of the ceramic substrate 1, and the electronic component 3 mounted on the lower surface of the ceramic substrate 1 is not shown, which is made of a thermosetting resin such as an epoxy resin. It is sealed with a resin sealing material.
[0016]
If the metallized wiring layer 2, metallized via pillar 4, metallized die attach layer 5, and metallized seal layer 6 are made of, for example, tungsten metallized, an organic binder, solvent, plasticizer, and dispersant suitable for tungsten powder are used. A metallized paste adjusted to an appropriate viscosity by adding, etc., is applied to each ceramic green sheet for the ceramic substrate 1 using a conventionally known screen printing method to form a predetermined pattern having a thickness of 12 to 25 μm and the ceramic green sheet. A predetermined cylindrical shape having a penetrating diameter of about 50 to 300 μm is printed and applied, and fired together with a ceramic green sheet laminate for the ceramic substrate 1 to be disposed on the upper and lower surfaces and inside of the ceramic substrate 1.
[0017]
The exposed surfaces of the metallized wiring layer 2, the metallized die attach layer 5, and the metallized seal layer 6 prevent the metallized conductor from being oxidized and corroded, and the metallized wiring layer 2, the bonding wire 7, the solder bump 8, and the socket. In general, a nickel plating layer having a thickness of about 1 to 10 μm is used to improve the connection between the metallized die attach layer 5 and the electronic component and the metallized seal layer 6 and the lid. A gold plating layer having a thickness of about 0.1 to 3 μm is applied.
[0018]
Further, on the upper surface of the ceramic substrate 1, a thick film layer 9 thicker than the metallized wiring layer 2 deposited on the upper surface is deposited by about 10 to 50 μm. The thick film layer 9 is made of, for example, a ceramic material substantially the same as that of the ceramic substrate 1, and as shown in a top view in FIG. 2, the thick film layer 9 surrounds the center of the surface at at least three points. A plurality of a plurality of rectangular patterns are deposited on the outer peripheral portion and the central portion. When the ceramic wiring board is placed on a placement surface such as a tray, the thick film layer 9 serves as a placement contact surface in contact with the placement surface, and the metallized wiring layer 2 is placed thereon. Since it is attached so as to surround the center of the surface at least three of them, the ceramic wiring board of the present invention is attached to, for example, a transport tray or the like. When placing on the placement surface, the metallized wiring layer 2 deposited on the upper and lower surfaces of the ceramic substrate 1 is placed by placing the surface on which the thick film layer 9 is deposited on the placement surface side. It can be placed without directly contacting the placing surface such as a tray. Therefore, according to the ceramic wiring board of the present invention, it is possible to effectively prevent the metallized wiring layer 2 from being scratched by the rubbing surface such as the tray or the like and from being attached with foreign matters. It is possible to connect the electrodes of the electronic components 3 mounted on the metallized wiring layer 2 and the metallized wiring layer 2 very well via conductive connection members such as bonding wires 7 and solder bumps 8.
[0019]
When the thickness of the thick film layer 9 is less than 10 μm thicker than the thickness of the metallized wiring layer 2, the ceramic wiring board of the present invention is mounted on a mounting surface such as a tray with the thick film layer 9 side down. When placed, only a slight gap is formed between the placement surface and the metallized wiring layer 2, which increases the risk of contact between the placement surface and the metallized wiring layer 2. Is more than 50 μm thicker than the thickness of the metallized wiring layer 2, the connection of the electrode of the electronic component 3 to the metallized wiring layer 2 through a conductive connection member such as a bonding wire 7 or a solder bump 8 is performed. There is a greater risk of obstacles. Accordingly, the thickness of the thick film layer 9 is preferably 10 to 50 μm thicker than the thickness of the metallized wiring layer 2 on the surface on which the thick film layer 9 is deposited. If the thick film layer 9 is formed of substantially the same material as the ceramic substrate 1, the thick film layer 9 and the ceramic substrate 1 are firmly bonded, and the thick film layer 9 is peeled off from the ceramic substrate 1. This can be effectively prevented. Therefore, the thick film layer 9 is preferably formed of substantially the same material as that of the ceramic substrate 1.
[0020]
Such a thick film layer 9 is, for example, a thick film paste obtained by adding and mixing an appropriate organic binder, solvent, etc. to the raw material powder substantially the same as the ceramic raw material powder contained in the ceramic green sheet for the ceramic substrate 1. Is applied to a ceramic green sheet for the ceramic substrate 1 in a predetermined pattern which is thicker than the metallized paste for the metallized wiring layer 2 by adopting a conventionally known screen printing method, and this is laminated on the ceramic green sheet for the ceramic substrate 1 By firing together with the body, it is deposited on the upper surface of the ceramic substrate 1 in a predetermined arrangement. At this time, the conductive paste is not brought into contact with the base plate by firing the surface on which the thick film paste for the thick film layer 9 is applied, so that the conductive paste does not contact the base plate. It is possible to effectively prevent the metallized wiring layer 2 from being damaged.
[0021]
Thus, according to the ceramic wiring board of the present invention, the metallized wiring layer 2 is not damaged or attached, and the electrodes of the respective electronic components 3 can be satisfactorily connected to the metallized wiring layer 2, and the mounted electronic The component 3 can be operated normally.
[0022]
It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, a thick film is used. Although the layer 9 is formed on the upper surface of the ceramic substrate 1, the thick film layer 9 may be formed on the lower surface of the ceramic substrate 1. In this case, it may be placed on a placing surface such as a tray with the lower surface side to which the thick film layer 9 is attached facing down.
[0023]
In the example of the embodiment described above, the thick film layer 9 has a plurality of substantially rectangular patterns dispersed in the outer peripheral portion and the central portion of the ceramic substrate 1 so as to surround the center of the surface at at least three of them. However, if the thick film layer 9 is disposed so as to surround the center of the surface at at least three of the thick film layers 9, the pattern of another shape such as a square or a circle is centered. A plurality of the outer peripheral portions and the outer peripheral portion may be dispersed and attached, or may be attached to a frame-like pattern surrounding the central portion of the ceramic substrate 1.
[0024]
Furthermore, in the above-described embodiment, the thick film layer 9 is formed of substantially the same material as the ceramic base 1, but the thick film layer 9 is different from the ceramic base 1 such as a metallized metal layer. It may be formed from a material.
[0025]
【The invention's effect】
According to the ceramic wiring board of the present invention, a thick film layer thicker than the metallized wiring layer is disposed on at least one of the upper and lower surfaces of the ceramic substrate so as to surround the center of the surface at at least three of them. Therefore, when placing this ceramic wiring board on a tray or the like, or when placing a ceramic green sheet laminate for a ceramic wiring board on a base plate for firing during the production of this ceramic wiring board, By placing the thick film layer side down, it is possible to prevent the metallized wiring layer deposited on this surface from rubbing against the placement surface, and as a result, scratches and foreign matter adhere to the metallized wiring layer. There is provided a ceramic wiring board in which each electrode of an electronic component to be mounted can be satisfactorily connected to a metallized wiring layer via a conductive connecting member so that the electronic component can always operate normally. It is possible.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a ceramic wiring board according to the present invention.
2 is a top view of the ceramic wiring board shown in FIG. 1 excluding electronic components 3 and bonding wires 7. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ceramic substrate 2 ... Metallized wiring layer 3 ... Electronic component 7 ... Bonding wire 8 as a conductive connection member ... As a conductive connection member Solder bump 9 thick layer

Claims (3)

A metallized wiring layer in which electrodes of electronic components are respectively connected to the upper and lower surfaces of the ceramic base having a substantially flat upper and lower surface via a conductive connection member is attached to at least one of the upper and lower surfaces. rather thickness than the metallized wiring layer is deposited, and a thick film layer has thin than electronic components mounted on said surface, arranged so as to surround the center of the surface at least three points on the thick film layer A method of manufacturing a ceramic wiring board formed by applying
A method for producing a ceramic wiring board, wherein the ceramic green sheet laminate as the ceramic wiring board is fired in a state of being placed on a base plate for firing with the thick film layer side down.   2. The ceramic wiring board according to claim 1, wherein the thick film layer is provided in an outer peripheral area of the ceramic wiring board having a rectangular shape in a plan view and an inner area of the outer peripheral area. Manufacturing method. An electronic device in which an electronic component is mounted on the ceramic wiring board obtained by the manufacturing method according to claim 1.

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