JP5535451B2 - Ceramic wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic wiring board having a wiring pattern made of a refractory metal and having a bonding pad having a residual stress relaxation effect when bonded to an object to be bonded, and a method for manufacturing the same.

Conventionally, when a thick film or thin film wiring board is mounted on a mother board made of a printed wiring board or a heat sink equipped with a heat sink, a solder ball mainly composed of Sn (tin) and Pb (lead) is used. The solder balls were also used as electrodes.
In this case, if the diameter of the bonding bumps made of solder balls is made constant, the larger the distance between the thick film or thin film wiring board and the mother board or heat sink to be mounted, the more the bonding bumps. Deformability increases, and a high residual stress relaxation effect can be expected.
On the other hand, bumps are formed at the time of mounting, which increases costs and increases the thickness of the assembly consisting of the thick film or thin film wiring board and the mounting target. This is not desirable.
In order to solve such problems, various researches and developments have been conducted in the past, and some inventions and devices have been disclosed.

For example, Patent Document 1 discloses an invention relating to a flip-chip connection structure using a solder bump of a semiconductor package under the name of “semiconductor bump connection structure and its manufacturing method”, and its manufacturing method.
The invention described in Patent Document 1 is a flip-chip connection structure in which an electrode of a first electronic component and an electrode of a second electronic component are connected by a solder bump. An electrode of a solder bump and an electrode of a second electronic component And a solder bump adjacent to the intermetallic compound layer in at least one of the joints on the first electronic component side and the second electronic component side on the side surfaces of the solder bumps. A constriction is formed at a position on the mother phase side.
According to the invention described in Patent Document 1 having the above configuration, the stress generated by the difference in thermal expansion coefficient due to the constriction formed on the side surface of the solder bump can be relaxed on the solder mother phase side.
Therefore, the reliability of the joined body obtained by joining the first electronic component and the second electronic component with the solder bumps can be improved.

JP 2007-128982 A

In recent years, as electronic components have been reduced in size, there has been a movement to eliminate Pb from electronic components in consideration of the environment.
As a result, Pb-free solder has been used as a substitute for solder mainly composed of Sn (tin) and Pb (lead) used for joining electronic components.
On the other hand, the Pb-free solder as described above has a property that the melting temperature is high and the deformability is low as compared with conventional solders mainly composed of Sn (tin) and Pb (lead). When the solder used in the invention described in Patent Document 1 was replaced with the Pb-free solder as described above, a sufficient stress relaxation effect was not exhibited.

  The present invention has been made in response to such a conventional situation, and it is possible to reduce the size of an electronic component by reducing the thickness of a joined body in which a wiring board made of a ceramic and a refractory metal is mounted on a mounting target. Even in such a case, it is an object of the present invention to provide a ceramic wiring board and a method for manufacturing the same, which can provide a sufficient residual stress relaxation effect to the joint without adding a complicated process of forming bumps and the like.

In order to achieve the above object, a ceramic wiring board according to a first aspect of the present invention is a ceramic wiring board that is bonded to an object to be mounted using Pb-free solder, and is formed on a ceramic board and the surface of the board. A first wiring pattern to be formed; and a second wiring pattern formed on the back side of the substrate for mounting the substrate on the mounting target. The substrate has a third wiring pattern in the interior thereof. a multilayer substrate comprising, first, third wiring pattern is made of W or Mo, and is formed by co-firing, the first to third wiring patterns are electrically connected, the second wiring pattern is made of Cu, is not less 20μm or more thick, countless pores formed therein, is formed in a region to be joined with the Pb-free solder is characterized in Rukoto.
In the invention having the above-described configuration, the substrate on which the ceramic base is laminated functions as an insulator, and the first and third wiring patterns function as a conductor, so that they are integrated as a wiring substrate. Works. Further, the first and third wiring patterns are formed of W (tungsten) or Mo (molybdenum), which is a refractory metal, so that the reliability of the wiring board according to claim 1 is improved. When the first and third wiring patterns are formed of W or Mo, a conductive paste containing W or Mo as a main component is applied onto an unfired ceramic molded body by a screen printing method. It is necessary to laminate the formed products to form a laminate .
In this case, the screen printing method is used to increase the dimensional accuracy of the corners in the planar shape of the first and third wiring patterns.
That is, by forming the first and third wiring patterns from W or Mo, there is an effect that an alignment pattern suitable for chip mounting and wire bonding can be formed accurately and finely.
The second wiring pattern acts as a bonding pad when the ceramic wiring board according to claim 1 is mounted on the mounting target, and at the same time , the first wiring pattern is connected to the first wiring pattern via the third wiring pattern . connected second and electrical wiring pattern also acts as an electrode in Rukoto.
Furthermore, the second wiring pattern is formed of Cu (copper) and has a thickness of 20 μm or more, thereby providing an effect of imparting deformability to the second wiring pattern.
Thereby, when the ceramic wiring board according to claim 1 is bonded to the mounting target, the second wiring pattern is deformed without tearing when residual stress is generated due to the difference in thermal expansion coefficient between them. This has the effect of relaxing the residual stress.
Further, by using the multilayer substrate according to the first aspect of the invention, it is possible to form multi-chip mounting and control wiring for driving the chip, and further reduce the size of the highly reliable wiring substrate. Have
In addition, the substrate, the first wiring pattern, and the third wiring pattern are formed by simultaneous firing, so that a substrate provided with the third wiring pattern is temporarily created. Compared to the case where a first wiring pattern made of W or Mo, which is a high melting point metal, is separately formed on the surface, the manufacturing process is simplified. Moreover, since the 1st wiring pattern and the 3rd wiring pattern are the same W or Mo material, it has the effect | action which improves the connection reliability between both wiring.

Ceramic wiring substrate is a second aspect of the present invention, there is provided a ceramic wiring board according to claim 1, the first wiring pattern and the second wiring pattern includes a further comprising a plated coating on the surface thereof To do.
Present aspect, in addition to the same operation as inventions of claim 1, by forming a plated film on the surface of the first and second wiring patterns, mounting of the chip and wire bonding (WB) Or the mountability of the ceramic wiring board according to claim 2 on the mounting target, and the metal forming the first and second wiring patterns is oxidized or reacted with moisture and compounds in the atmosphere. And has an effect of preventing deterioration.

A method for manufacturing a ceramic wiring board according to a third aspect of the present invention is a method for manufacturing a ceramic wiring board to be bonded to an object to be mounted using Pb-free solder, comprising mixing a ceramic powder raw material and an organic binder. A first wiring pattern is formed with a first conductive paste mainly composed of W or Mo on the surface of the laminate formed by laminating ceramic molded bodies, and a first conductive paste is provided between the layers of the laminate. A first step of forming a third wiring pattern; a second step of simultaneously firing the ceramic molded body and the first conductive paste to form a ceramic multilayer substrate after the first step; after the second step, and baking the second conductive paste mainly composed of Cu in the region to be joined with the Pb-free solder of the back surface of the ceramic multilayer substrate, a thickness of 20μm or less , And the ones inside the have a third step of forming a second wiring pattern having a myriad of holes, the first to third wiring pattern, characterized in that it is electrically connected It is.
In the invention having the above-described configuration, the first and second steps have an effect of forming a ceramic wiring board ( multilayer board) using ceramic as an insulator and W or Mo as a conductive material as a refractory metal. Moreover, such a ceramic wiring board has the effect of reducing the size while maintaining the reliability of the board.
In the first step, since the first and third wiring patterns are formed by the screen printing method, it has an effect of increasing the dimensional accuracy of the corners in the planar shape.
Therefore, it has the effect of forming an alignment pattern (first wiring pattern) suitable for chip mounting and wire bonding.
In the third step, Cu having a thickness of 20 μm or more is electrically connected to the first and third wiring patterns on the back surface side of the ceramic wiring substrate and in a region bonded to the Pb-free solder. This has the effect of forming a layer (second wiring pattern) .
The Cu layer according to the third aspect of the invention acts as a bonding pad when mounted on the mounting target. Furthermore, in particular, the first and third wiring patterns and the Cu layer (second wiring pattern) are electrically connected, so that the second wiring pattern also functions as an electrode.
Then, the second wiring pattern, wherein the ceramic wiring board produced by the method of claim 3 wherein the, when implemented in a more mountable subject Pb freehand Da, due to the respective thermal expansion coefficient difference Residual stress that occurs is relaxed by its deformability, and it has the effect of preventing defects such as breakage at the joint.
Therefore, it has the effect | action of improving the reliability of the joined body which consists of a ceramic wiring board manufactured by the method of Claim 3, and a mounting object.
In addition, since the Cu layer according to claim 3 is formed by baking the second conductive paste, the auxiliary component contained in the conductive paste is different from that formed by plating, melting, or vapor deposition. The inside has countless holes due to the influence of the resin component.
For this reason, the Cu layer according to claim 3 has an effect that the relaxation effect of the residual stress is increased by increasing the deformability as compared with the Cu layer formed by electrolytic plating.

Method for producing a ceramic wiring substrate is a fourth aspect of the invention is a method for producing a ceramic wiring board according to claim 3, the third step, second by screen printing on the back surface of the ceramic multilayer substrate A third wiring step for forming the second wiring pattern using the conductive paste and a third step for baking the second conductive paste after the third step. It is characterized by.
The invention configured as described above has the same operation as the method according to the third aspect .
Further, in the invention according to claim 4 , by forming the Cu layer by the two processes of 3-1 and 3-2, the Cu layer having a high residual stress relaxation action is formed by a small number of processes. Has an effect.

The method for producing a ceramic wiring board according to claim 5 is the method for producing a ceramic wiring board according to claim 3 , wherein the third step is a screen printing method on the back surface of the ceramic multilayer board. A third process for forming a solid pattern using the second conductive paste, a third process for firing the second conductive paste after the third process, and a third process for baking the second conductive paste. After the step -2, a third step of forming a second wiring pattern from the fired solid pattern by an etching method is provided.
The invention configured as described above has the same operation as the method according to the third aspect .
Further, in the invention according to claim 5 , by forming the Cu layer by the three steps of 3-1 to 3-3, the Cu layer is precise and highly reliable and has innumerable holes therein. It has the effect | action of forming.

According to the first aspect of the present invention, by using W or Mo for the first and third wiring patterns, it is possible to increase the dimensional accuracy of the corners in the planar shape.
Therefore, it has the effect that the position accuracy of the mounted chip and the wire bond can be increased.
In addition, since the roundness of the corners in the planar shape of the first wiring pattern as the chip mounting portion can be suppressed to several μm or less, the self-alignment effect at the time of chip mounting can be enhanced.
As a result, there is an effect that it is possible to stably bond a mounted object such as an element to the ceramic wiring substrate according to claim 1.
In addition, by providing the second wiring pattern made of Cu having a thickness of 20 μm or more on the back surface side of the substrate, when mounting on, for example, a mother board or a heat sink, the difference in thermal expansion coefficient between There is an effect that the residual stress generated due to this can be relaxed by the deformability of the second wiring pattern.
In other words, when the ceramic wiring board according to claim 1 is bonded to the mounting target, the bonded portion can be prevented from being broken by the residual stress caused by the difference in thermal expansion coefficient.
As a result, if you are use the second wiring pattern and the electrodes of the first to third wiring patterns are electrically connected, to the first wiring pattern formed from the second wiring pattern on the substrate Therefore, it is possible to improve the reliability of the joined body composed of the mounting target and the ceramic wiring board according to claim 1.
Furthermore, by using the multilayer substrate according to the first aspect of the invention, it is possible to reduce the size while maintaining the reliability of the substrate, and to form a control wiring for driving a multi-chip mounting or chip. Have.
In addition, by forming the first and third wiring patterns by simultaneous firing, after the multilayer substrate having the third wiring pattern is manufactured, the first wiring pattern is separately formed on the surface by a post-fire method. Compared to the case, the manufacturing process can be simplified. As a result, the invention according to claim 1 can be provided at low cost.

According to a second aspect of the present invention, a plating film is provided on the surfaces of the first and second wiring patterns, that is, on the surface of the wiring pattern exposed to the outside air, so that the ceramic wiring board according to the second aspect is provided. It has the effect of improving reliability, improving the mountability of the chip and this ceramic wiring board, and preventing the wiring pattern from being oxidized and deteriorating due to chemical reaction with moisture and compounds in the atmosphere. .

The invention described in claim 3 captures the invention described in claim 1 as a method invention, and has the same effect as the invention described in claim 1.
Further, in the method according to claim 3 , by forming the second wiring pattern by the baking method, there is an effect that innumerable holes can be formed in the second wiring pattern.
As a result, since the deformability of the second wiring pattern is increased, the effect of reducing the residual stress can be enhanced.

The invention according to claim 4, the third step in the method according to claim 3 3-1, by performing the first 3-2 two steps, the second consisting of Cu layer with a hole It has the effect that the manufacturing process of a ceramic wiring board provided with a wiring pattern can be simplified.
Therefore, it is possible to provide an inexpensive product that is highly reliable and has excellent productivity by forming a pattern by a screen printing method.

The invention according to claim 5 by performing the third of the steps 3-1 to 3-3 of the three steps in the method according to claim 3, the consist sophisticated a porous Cu layer 2 wiring patterns can be formed.
That is, the width of the second wiring pattern can be narrowed and miniaturized, and a higher density can be achieved.
In this case, the effect of relieving residual stress is improved by the second wiring pattern, so that a highly reliable product can be provided.

  Hereinafter, a ceramic wiring board and a method for manufacturing the same according to the preferred embodiment of the present invention will be described in detail with reference to FIGS.

First, a description will be given of circumstances that led to this gun onset Akira is made.
Since Cu is more deformable by external stress than W or Mo, which is a refractory metal, a relaxation effect of high residual stress generated during bonding can be expected by forming a bonding pad from Cu. Cu is also an excellent conductive material.
For this reason, the inventors directly printed a conductive paste mainly composed of Cu on the front and back surfaces of the ceramic molded body and co-fired with the ceramic molded body, whereby Cu is a mounting pad for mounting elements and the like. A ceramic sintered body having a wiring pattern on the front surface and a bonding pad made of Cu for bonding the ceramic sintered body itself to an object to be bonded was prepared.
However, the corners in the plane direction of the Cu wiring pattern serving as the mounting pad are rounded by about 20 μm. When the elements are mounted on the wiring pattern with rounded corners with the solder paste, the bonding of the elements In some cases, the self-alignment effect is not exhibited, and the device is liable to be displaced.
Further, for example, when a Cu wiring pattern formed on the upper surface side of the ceramic sintered body described above with a die bonder is used as an element mounting pad, the device cannot be recognized if the corners of the Cu wiring pattern are rounded. There was a case.

As a result of intensive studies, the inventors have noted that the bonding surface of electronic components such as elements mounted on the upper surface of the ceramic sintered body is smaller than the bonding surface of the ceramic sintered body bonded to the object to be bonded. A wiring pattern that can clearly form corners in the plane direction of the wiring pattern is formed on the surface side of the ceramic sintered body with a substantially narrow joint surface by screen printing using a refractory metal. On the other hand, by forming a bonding pad with a Cu layer having a sufficient thickness on the back side of the ceramic sintered body having a substantially wide bonding surface, the residual stress at the time of bonding to the object to be bonded can be reduced. It has been found that it can be effectively mitigated by deformation.
In other words, the ceramic wiring board according to the present invention uses different metals for the element mounting pad formed on the upper surface and the bonding pad for mounting the ceramic wiring board on the object to be bonded, so that the element etc. In this configuration, the residual stress when the ceramic wiring board is mounted on the object to be bonded can be sufficiently relaxed while preventing the trouble when mounting the ceramic wiring board on the upper surface side of the ceramic wiring board.

A ceramic wiring board according to Embodiment 1 of the present invention will be described in detail with reference to FIGS. (Corresponding to claims 1 to 5 )
1 is a cross-sectional view of a ceramic wiring board according to a first embodiment of the present invention.
The ceramic wiring board 1a according to Example 1 has a wiring pattern shape on the lower surface 2b side of the substrate 2 formed of ceramic as an insulator and W or Mo as a refractory metal, that is, on the mounting surface side. By providing the bonding pad formed of the Cu layer, the residual stress generated when mounting on the mounting target can be relieved due to its deformability.
More specifically, as shown in FIG. 1, the ceramic wiring board 1a according to the first embodiment has a wiring pattern 4 made of W or Mo on the upper surface 2a of the board 2 on which the ceramic base 3 is laminated. A wiring pattern 8 made of W or Mo is also provided on the lower surface 2b side, and a bonding pad made of a Cu layer 9 having a thickness A of 20 μm or more is provided on the surface of the wiring pattern 8 provided on the lower surface 2b side of the substrate 2. Is.
In this case, since the wiring pattern 8 becomes a base (base) for forming the Cu layer 9, it can be said that it is a base pattern.
Further, in the ceramic wiring substrate 1a, the surface of the wiring patterns 4 and 8 is provided with a plating film 10 made of, for example, Ni (nickel), Au (gold), or Ag (silver).
By forming the plating film 10 in this manner, the chip and WB mountability and the mountability of the ceramic wiring board 1a according to the embodiment on the mounting target are improved, and the wiring pattern 4 and the wiring pattern 8 are provided. It prevents oxidation and chemical reaction with compounds in the atmosphere and deterioration.

Further, by forming the substrate 2 from a refractory metal and ceramic, there is an effect that high reliability can be imparted while the substrate 2 is downsized.
In addition, when the wiring pattern 4 is formed of W or Mo, as will be described later, a conductive paste containing W or Mo as a main component is applied by screen printing on the surface of the unfired ceramic molded body. Need to form.
In this case, an alignment pattern suitable for chip mounting and wire bonding can be formed by increasing the dimensional accuracy of the corners in the planar shape of the wiring pattern 4 formed on the surface of the unfired ceramic molded body. It has the effect.
Therefore, it has the effect that the position accuracy of the mounted chip and the wire bond can be increased.
Moreover, since the roundness of the corners in the planar shape of the wiring pattern 4 of the chip mounting portion can be set to several μm or less, there is an effect that the self-alignment effect at the time of chip mounting can be enhanced.
As a result, there is an effect that an object to be mounted such as an element can be bonded in a stable state on the ceramic wiring board 1a according to the first embodiment.

In the ceramic wiring board 1a according to the first embodiment, for example, as shown in FIG. 1, a wiring pattern 7 made of W or Mo is provided between the bases 3 and 3, and the wiring pattern 4 and the wiring pattern 7 are provided. Alternatively, the wiring pattern 7, the wiring pattern 8, and the conductor 6 filled in the via 5 formed in the base 3 may be electrically connected. That is, the substrate 2 may be a multilayer substrate (co-fired multilayer substrate).
In this case, each of the wiring patterns 4 and 7 and the wiring pattern 8 do not necessarily have to be electrically connected. That is, the wiring pattern 8 may be formed on the lower surface 2b of the substrate 2 only for the purpose of forming the Cu layer 9 to be a bonding pad, that is, as a base pattern for forming the Cu layer 9.
When high dimensional accuracy is not required for the wiring patterns 4 and 8, the wiring patterns 4 and 8 formed on the upper surface 2a and the lower surface 2b of the substrate 2 include the flat substrate 2 or the wiring pattern 7 inside. After the substrate 2 which is a co-fired multilayer substrate is manufactured, for example, a pattern is formed by a screen printing method using a Cu paste, and then a pattern made of the substrate 2 and the Cu paste is formed again by a post-fire method or the like. May be.
Thus, when the substrate 2 is a co-fired multilayer substrate, there is an effect that the substrate 2 can be further reduced in size while maintaining the reliability of the substrate 2.
The ceramic wiring board 1a according to the first embodiment as described above is used by being mounted on, for example, a mother board made of a printed wiring board, a heat sink provided with a heat sink, or the like to be mounted.

FIG. 2 is a cross-sectional view when the ceramic wiring board according to the first embodiment of the present invention is mounted on a printed wiring board. In addition, the same code | symbol is attached | subjected about the part same as what was described in FIG. 1, and the description about the structure is abbreviate | omitted.
As shown in FIG. 2, in the bonded body 23 when the ceramic wiring board 1 a according to the first embodiment is mounted on a printed wiring board, for example, a wiring pattern 16 made of a conductor 25 is formed on a resin board 15. For example, it is configured to be mounted on the mounting portion 26 of the mother board 14 having the plating film 17 formed on the surface thereof via, for example, Pb-free solder 24.
When the ceramic wiring board 1 a according to the first embodiment is mounted on the mother board 14, the solder 24 is melted and the ceramic wiring board 1 a is bonded onto the mounting portion 26. At this time, since there is a difference between the thermal expansion coefficient of the base 3 constituting the substrate 2 and the thermal expansion coefficient of the substrate 15 constituting the mother board 14, the base 3 and the substrate 15 are melted when the solder 24 is melted and then cooled. Residual stress due to the difference in thermal expansion coefficient is generated in each of these.
That is, when the base 3 and the substrate 15 having different thermal expansion coefficients are joined, if the solder 24 is melted and cooled, the substrate 15 is warped.

Until now, when bonding the ceramic wiring board to the mother board 14, solder containing Sn (tin) and Pb (lead) in a ratio of, for example, 63:37 has been used. Pb-free solder that does not contain Pb has come to be used.
On the other hand, since this Pb-free solder is less deformable than a conventional solder containing Pb, it cannot be expected to have a sufficient residual stress relaxation effect during bonding.
Therefore, as a result of intensive studies, the inventors have made a wiring pattern-like Cu having a thickness of 20 μm or more on the mounting surface side of the ceramic substrate 2 provided with the conductor 6 made of a high melting point metal such as W or Mo. It was found that by forming the layer 9 and joining the ceramic wiring substrate 1a and the mother board 14 via the Cu layer 9, the residual stress can be relaxed by utilizing the deformability of Cu at the time of joining.

  Therefore, in the ceramic wiring board 1a according to the first embodiment, when the Cu layer 9 having a wiring pattern shape having a thickness of 20 μm or more is provided as a bonding pad on the lower surface 2b side of the board 2, the bonding is performed on the mother board 14. It has an effect that it is possible to prevent the occurrence of defects such as cracks at the joints.

  Furthermore, in the ceramic wiring board 1a according to the first embodiment, the wiring pattern-like Cu layer 9 can shorten the heat conduction path as compared with the case where the shape is formed in a substantially spherical shape and arranged in a grid shape, As a result, there is an effect that heat can be radiated smoothly.

In FIG. 2, the case where the ceramic wiring board 1a according to the first embodiment is bonded to the mother board 14 made of the resin board 15 is taken as an example. However, the board 15 is a ceramic board, a film board, or a heat dissipation board. It may be a heat sink having a plate.
In this way, when there is a difference in the thermal expansion coefficient between the material constituting the substrate 2 and the material constituting the mother board 14, the Cu layer 9 exhibits a residual stress relaxation effect, such as cracking at the time of bonding or use. It has the effect of suppressing the occurrence of defects.

Here, the manufacturing process of the ceramic wiring board 1a according to the first embodiment will be described in detail with reference to FIG. ( Reference example )
3 (a) to 3 (e) are cross-sectional views illustrating the manufacturing process of the ceramic wiring board according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected about the same part as what was described in FIG. 1 or FIG. 2, and the description about the structure is abbreviate | omitted.
In order to manufacture the ceramic wiring board 1a according to the first embodiment, first, as shown in FIG. 3A, a ceramic powder raw material and an organic binder are mixed, and, for example, a tape-like material is formed by a doctor blade method or the like. A ceramic molded body 11 is prepared, and a conductive paste 12 is printed and filled on the ceramic molded body 11 formed with the vias 5 by punching. Further, the conductive paste 12 is printed on the upper and lower surfaces of the ceramic molded body 11. As shown in FIG. 3B, a plurality of the wiring patterns 4 and wiring patterns 8 formed thereon are laminated as necessary to form a temporary laminated body 13 of ceramic green sheets (step S1). S2).

After this step S2, as shown in FIG. 3 (c), the ceramic green sheet temporary laminate 13 is fired under a temperature condition of 1500 ° C. or higher to form an upper surface 2a of the insulator made of the ceramic substrate 3. The wiring pattern 4, the wiring pattern 8 on the lower surface 2b, and the ceramic sintered body 27 provided with the wiring pattern 7 inside the substrate 2 as necessary (step S3).
Note that the wiring patterns 4 and 8 formed on the upper surface 2a and the lower surface 2b of the substrate 2 are a flat substrate 2 or a co-fired multi-layer having the wiring pattern 7 therein if the dimensional accuracy is not required. After manufacturing the substrate 2 which is a substrate, it may be formed by, for example, a post-fire method or the like.
In particular, when the wiring patterns 4, 7, 8 and the substrate 3 are fired at the same time, the manufacturing process can be simplified as compared with the case where the wiring patterns 4, 8 are formed by a post-fire method or the like. Has an effect.

Further, after this step S3, as shown in FIG. 3D, the Cu layer 9 may be formed by plating (step S4). That is, the substrate 2 may be immersed in the plating solution to form the Cu layer 9 having a thickness of 20 μm or more on the surface of the wiring pattern 8 (underlying pattern) (step S4).
At this time, in order to prevent the formation of the Cu layer on the surface of the wiring pattern 4 exposed on the upper surface 2a of the substrate 2, it is necessary to mask the upper surface 2a side of the substrate 2.
Further, when the Cu layer 9 is formed by plating, the Cu layer 9 can be formed without subjecting the substrate 2 to heat treatment.

Finally, after this step S4, the plating film 10 made of a noble metal such as Ni or Au may be formed on the surface of the wiring pattern 4 and the Cu layer 9 by plating again (step S5).
In this case, it is possible to improve the mountability of the chip, wire bonding, and ceramic wiring substrate, and to prevent the surface of the wiring pattern 4 and the Cu layer 9 from being oxidized or reacting with a compound or water in the atmosphere to be deteriorated. it can.
Therefore, also from this point, the reliability of the ceramic wiring board 1a according to the first embodiment can be improved.

A ceramic wiring board according to a second embodiment of the present invention will be described in detail with reference to FIGS. (Corresponding to claims 1 to 5 )
The ceramic wiring board according to the second embodiment has substantially the same configuration as the ceramic wiring board according to the first embodiment, but the Cu layer 18 is directly formed on the lower surface 2b side of the substrate 2 without the wiring pattern 8 interposed therebetween. Is different. Here, a description will be given with emphasis on differences from the ceramic wiring board 1a according to the first embodiment.
FIG. 4 is a sectional view of a ceramic wiring board according to the second embodiment of the present invention. The same parts as those described in FIGS. 1 to 3 are denoted by the same reference numerals, and description of the configuration is omitted.
As shown in FIG. 4, in the ceramic wiring board 1b according to the second embodiment, the Cu layer 18 is directly formed on the lower surface 2b of the board 2 without using the wiring pattern 8, or the Cu layer 18 itself becomes a wiring. A plating film 10 made of Ni, Au, or Ag (silver) is formed on the surfaces of the wiring pattern 4 and the Cu layer 18.
When the Cu layer 18 and the conductor 6 filled in the via 5 formed in the base 3 are electrically connected, the Cu layer 18 transmits an electrical signal to the wiring pattern 7 and the wiring pattern 4. It also acts as an electrode.
The ceramic wiring board 1b according to the second embodiment as described above has the same effects as the ceramic wiring board 1a according to the first embodiment.

Here, the manufacturing method of the ceramic wiring board 1b according to the second embodiment will be described in detail with reference to FIGS.
In addition, the manufacturing method of the ceramic wiring board 1b which concerns on Example 2 is the method (1) which prints the electrically conductive paste which has Cu as a main component on the lower surface 2b of the board | substrate 2 in the wiring pattern shape, and heat-fires this electrically conductive paste. There are two types of methods (2): a solid pattern is formed on the lower surface 2b of the substrate 2 with a conductive paste containing Cu as a main component, and then a wiring pattern is formed by an etching method.

First, the manufacturing method (1) of the ceramic wiring board 1b will be described in detail with reference to FIG.
5 (a) to 5 (f) are cross-sectional views illustrating the manufacturing process of the ceramic wiring board according to the second embodiment of the present invention. The same parts as those described in FIGS. 1 to 4 are denoted by the same reference numerals, and description of the configuration is omitted.
Moreover, in the manufacturing method (1) of the ceramic wiring board 1b according to the second embodiment, the processes (steps S1 to S3) until the ceramic sintered body 27 is manufactured are the manufacturing processes of the ceramic wiring board 1a according to the first embodiment. Since this is the same, the description of this part is omitted.
Furthermore, in FIG. 5, the case where the wiring pattern 8 is not provided on the lower surface 2b of the substrate 2 as in the case of the ceramic wiring substrate 1a according to the first embodiment is described as an example. You may have. The same applies to the manufacturing method (2) of the ceramic wiring board 1b according to Example 2 shown below.

In the manufacturing method (1) of the ceramic wiring board 1b according to the second embodiment, as shown in FIG. 5D, on the lower surface 2b side of the substrate 2 constituting the sintered ceramic sintered body 27, for example, a screen printing method is used. The wiring pattern 19 is formed by printing the conductive paste 20 containing Cu as a main component by, for example, (step S6).
After step S6, as shown in FIG. 5E, the conductive paste 20 is refired together with the substrate 2 to form the wiring pattern 19 made of the Cu layer 21 (step S7).
During this refiring, countless holes are formed inside the Cu layer 21 due to the influence of the auxiliary component and the resin component contained in the conductive paste 20.
In step S7, it is necessary to determine the thickness C of the conductive paste 20 to be formed in step S6 including the firing shrinkage so that the thickness D of the wiring pattern 19 after firing is 20 μm or more.

After step S7, as shown in FIG. 5F, a plating film 10 made of, for example, Ni, Au, or Ag is formed on the surfaces of the wiring pattern 4 and the wiring pattern 19 formed on the substrate 2. (Step S8).
Thus, in the manufacturing method (1) of the ceramic wiring board 1b according to the second embodiment, the wiring pattern 19 is formed by baking the conductive paste 20 mainly composed of Cu on the lower surface 2b of the board 2. The Cu layer 21 having the wiring pattern shape and having innumerable holes therein can be formed.
In this case, there is an effect that the deformability of the Cu layer 21 can be improved as compared with the Cu layer 9 according to the first embodiment formed by plating.
Therefore, it is possible to provide the ceramic wiring board 1b having a higher residual stress relaxation effect than the ceramic wiring board 1a according to the first embodiment.
As a result, the reliability of the ceramic wiring board 1b according to the second embodiment can be improved.
Since the Cu layer 21 is a conductor, it can also be used as an electrode for transmitting an electrical signal to the wiring pattern 4 or the wiring pattern 7.

Next, the manufacturing method (2) of the ceramic wiring board 1b will be described in detail with reference to FIG.
6 (a) to 6 (g) are cross-sectional views illustrating the manufacturing process of the ceramic wiring board according to the second embodiment of the present invention. The same parts as those described in FIGS. 1 to 5 are denoted by the same reference numerals, and description of the configuration is omitted.
Moreover, in the manufacturing method (2) of the ceramic wiring substrate 1b according to the second embodiment, the steps (step S1 to step S3) until the ceramic sintered body 27 is manufactured are the steps for manufacturing the ceramic wiring substrate 1a according to the first embodiment. Since this is the same as the process, description of this part is omitted.
In the manufacturing method (2) of the ceramic wiring substrate 1b according to the second embodiment, as shown in FIG. 6D, on the lower surface 2b side of the substrate 2 constituting the sintered ceramic sintered body 27, for example, a screen printing method is used. A solid pattern 22 is formed by printing the conductive paste 20 containing Cu as a main component by the above (step S9).
And after this step S9, as shown in FIG.6 (e), the conductive paste 20 is rebaked with the board | substrate 2, and the solid pattern 22 which consists of Cu layer 21 is formed (step S10).
During this refiring, countless holes are formed inside the Cu layer 21 due to the influence of the auxiliary component and the resin component contained in the conductive paste 20.
In step S7, it is necessary to determine the thickness E of the conductive paste 20 to be formed in step S6 including the firing shrinkage so that the thickness F of the solid pattern 22 after firing is 20 μm or more.

Then, after this step S7, as shown in FIG. 6 (f), the wiring pattern 19 is formed from the solid pattern 22 by, for example, an etching method (step S11). Further, after this step S11, FIG. As shown in FIG. 5, a plating film 10 made of, for example, Ni, Au, or Ag, which is a noble metal, may be formed on the surfaces of the wiring patterns 4 and 19 formed on the upper surfaces 2a and 2b of the substrate 2 (step S12). ).
Thus, in the manufacturing method (2) of the ceramic wiring board 1b according to the second embodiment, after forming the solid pattern 22 by baking the conductive paste 20 mainly composed of Cu on the lower surface 2b of the board 2, for example, By forming the wiring pattern 19 by the etching method, the wiring pattern 19 made of the Cu layer 21 having high dimensional accuracy can be formed.
That is, a more precise wiring pattern 19 can be formed. This means that according to the above method (2), the narrow wiring pattern 19 can be formed, and high-density wiring is possible.
Since the Cu layer 21 is a conductor, it can also be used as an electrode for transmitting an electrical signal to the wiring pattern 4 or the wiring pattern 7.

  As described above, the present invention provides a ceramic wiring board capable of exhibiting a sufficient residual stress relaxation effect at its joint even when a wiring board made of a ceramic and a refractory metal is mounted on a mounting target, and its This is a manufacturing method and can be used in the field of electronic components.

It is sectional drawing of the ceramic wiring board which concerns on Example 1 of this invention. It is sectional drawing at the time of mounting the ceramic wiring board based on Example 1 of this invention on a printed wiring board. (A)-(e) is sectional drawing which shows the manufacturing process of the ceramic wiring board based on Example 1 of this invention. It is sectional drawing of the ceramic wiring board which concerns on Example 2 of this invention. (A)-(f) is sectional drawing which shows the manufacturing process of the ceramic wiring board based on Example 2 of this invention. (A)-(g) is sectional drawing which shows the manufacturing process of the ceramic wiring board based on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b ... Ceramic wiring board 2 ... Board | substrate 3 ... Base | substrate 4 ... Wiring pattern 5 ... Via 6 ... Conductor 7 ... Wiring pattern 8 ... Wiring pattern 9 ... Cu layer 10 ... Plating film 11 ... Ceramic molding 12 ... Conductive paste 13 ... Temporary laminate of ceramic green sheets 14 ... Mother board 15 ... Substrate 16 ... Wiring pattern 17 ... Plating film 18 ... Cu layer 19 ... Wiring pattern 20 ... Conductive paste 21 ... Cu layer 22 ... Solid pattern 23 ... Bonded body 24 ... Solder 25 ... Conductor 26 ... Mounting part 27 ... Ceramic sintered body

Claims (5)

A ceramic wiring board to be bonded to an object to be mounted using Pb-free solder,
A ceramic substrate; a first wiring pattern formed on a surface of the substrate; and a second wiring pattern formed on a back surface side of the substrate for mounting the substrate on a mounting target. ,
The substrate is a multilayer substrate having a third wiring pattern therein,
The first and third wiring patterns are made of W or Mo and formed by simultaneous firing,
The first to third wiring patterns are electrically connected,
Said second wiring pattern is made of Cu, is not less 20μm or more thick, the ceramic wiring board countless pores formed therein, is formed in a region to be joined with the Pb-free solder, characterized in Rukoto .   The ceramic wiring board according to claim 1, wherein the first wiring pattern and the second wiring pattern are provided with a plating film on a surface thereof. A method for manufacturing a ceramic wiring board to be bonded to an object to be mounted using Pb-free solder,
While forming the first wiring pattern with the first conductive paste mainly composed of W or Mo on the surface of the laminate formed by laminating the ceramic molded body obtained by mixing the ceramic powder raw material and the organic binder , A first step of forming a third wiring pattern with the first conductive paste between the layers of the laminate;
After this first step, a second step of simultaneously firing the ceramic molded body and the first conductive paste to form a ceramic multilayer substrate;
After this second step, a second conductive paste containing Cu as a main component is baked on the area of the back surface of the ceramic multilayer substrate that is to be bonded to the Pb-free solder, and the thickness is 20 μm or more. We have a third step of forming a second wiring pattern having a hole,
The method of manufacturing a ceramic wiring board, wherein the first to third wiring patterns are electrically connected . The third step, by screen printing on the back surface of the ceramic multilayer substrate, a 3-1 step of forming the second wiring pattern by using the second conductive paste,
4. The method of manufacturing a ceramic wiring board according to claim 3 , further comprising a third step of baking the second conductive paste after the third step. The third step, the back surface of the ceramic multilayer substrate, by screen printing, a 3-1 step of forming a solid pattern using the second conductive paste,
After the step 3-1, the step 3-2 for firing the second conductive paste,
4. The method according to claim 3 , further comprising a third step of forming the second wiring pattern from the solid pattern fired by an etching method after the third step. A method for manufacturing a ceramic wiring board.