JP2001217518A - Wiring board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heating value of a resistor for external surge absorption which fills a hole formed in a substrate. SOLUTION: This wiring board is constituted by providing at least two of wiring layers 16 to 20 to a substrate 11 made of ceramic, glass ceramic, etc. A conductor 21 for an external input terminal which is provided to one wiring layer 16 is connected to a ground conductor 22 provided to the other wiring layer 20 through the resistance body 24 filling the hole 23 formed in the substrate 11, and the resistor 24 is formed of a mixture material obtained by mixing mainly a substrate material and a conductor and made porous. In this constitution, the electric resistance of the resistor 24 is much smaller than that of an officially reported resistor, so when a large external surge is applied, the heating value of the resistor 24 becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wiring board having a circuit protection function against an external surge and a method of manufacturing the same.

[0002]

2. Description of the Related Art Protection circuits against external surges are usually
It is composed of a varistor, a circuit combining a resistor and a capacitor, a gap resistor, and the like, and such a protection circuit of each configuration is mounted on a wiring board. In the case of each of these configurations, a space for mounting the protection circuit on the board is required, and the board becomes larger by that amount. On the other hand, in recent years, a wiring board having a configuration in which the space for mounting the protection circuit is minimized has been considered. One example is a wiring board described in Japanese Patent Application Laid-Open No. 11-68261.

In the wiring board disclosed in this publication, a hole such as a through hole or a via hole is provided in the board, a resistor is filled in the hole, and an external input terminal conductor is connected to a ground conductor via the resistor. It is configured to be. In this configuration, when an external surge is applied to the external input terminal conductor, the external surge is discharged to the ground conductor through the resistor filled in the hole, so that the circuit element and the like provided on the substrate are discharged. It is possible to protect from the external surge.

In the above configuration, since the resistor is filled in the hole provided in the substrate, a space (area) necessary for disposing the resistor is provided.
Can be an area slightly larger than the cross-sectional area of the hole, the space for mounting the protection circuit can be made as small as possible, and the board can be made smaller accordingly.

[0005]

In the case of the alumina multilayer substrate described in the above publication, the resistor is formed by firing a resistor paste which is a mixed material of alumina powder and tungsten powder. . However, since this fired resistor is filled with alumina and glass components between the tungsten particles, it has a characteristic that the electric resistance is considerably large, and when a large external surge is applied and flows through the resistor, In some cases, the calorific value of the resistor increases considerably. In this case, since the temperature of the resistor becomes high, there is a risk that the conductor around the resistor may be scorched or the substrate may be cracked.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wiring board capable of reducing the amount of heat generated by a resistor filled in a hole provided inside a board and a method of manufacturing the same.

[0007]

According to the first aspect of the present invention, the resistor filled in the hole of the substrate is formed of a mixed material obtained by mainly mixing a substrate material and a conductor, and is formed in a porous shape. Therefore, the electrical resistance of this resistor when a high voltage is applied is smaller than that of the resistor described in the above-mentioned publication. Therefore, even when a large external surge is applied, the amount of heat generated by the resistor can be relatively reduced.

According to the second aspect of the present invention, the resistor is formed by firing a mixture of a resin material and a mixture of a substrate material and a conductor. According to this configuration, a porous resistor can be easily formed. Further, in the case of the above configuration, as in the invention of claim 3, 10 to 70 vol.
% Is preferably mixed. Particularly, when the resin beads are mixed at 30 vol% in the mixed material as in the invention of claim 4, a resistor having the most preferable characteristics can be formed.

According to the fifth or sixth aspect of the present invention, the wiring board according to the first aspect can be easily manufactured.

[0010]

FIG. 1 to FIG. 6 show a first embodiment in which the present invention is applied to, for example, an alumina multilayer substrate.
This will be described with reference to FIG. First, FIG. 2 is an enlarged vertical sectional view of the alumina multilayer board (wiring board) 11 of the present embodiment. As shown in FIG. 2, the alumina multilayer substrate 11
For example, four alumina substrates 12, 13, 14, and 15 are stacked. The alumina multilayer substrate 11 includes:
A wiring layer 16 is provided on the upper surface (the upper surface of the alumina substrate 12), and four alumina substrates 12, 13, 14,
15, three wiring layers 17, 18 and 19 are provided, and the wiring layer 2 is formed on the lower surface (the lower surface of the alumina substrate 15).
0 is provided.

Each of the wiring layers 16 to 20 is formed of a conductor pattern (wiring pattern) having a required shape. Each of the conductor patterns is made of a conductor such as W or Mo. Here, at the right end in FIG. 2 of the wiring layer 16 on the upper surface of the alumina multilayer substrate 11, for example, an external input terminal pattern 21 is provided as an external input / output terminal conductor. This external input terminal pattern 21 includes:
An external input terminal (not shown) is formed. Also,
FIG. 2 showing the wiring layer 20 on the lower surface of the alumina multilayer substrate 11
At the middle right end, for example, a ground pattern 22 is provided as a ground conductor.

Further, in the portion of the alumina multilayer substrate 11 where the external input terminal pattern 21 and the ground pattern 22 face each other, for example, a via hole 23
Are provided in a direction perpendicular to the plate surface of the alumina multilayer substrate 11. The inner diameter of the via hole 23 is, for example, about 0.1 to 0.4 mm. The via hole 23 is filled with a resistor 24 having a resistance value of, for example, 100 kΩ or more. Both ends (upper and lower ends) of the resistor 24 are connected to the external input terminal pattern 21 and the ground pattern 22.

The resistor 24 is made of a mixed material obtained by mixing alumina as a substrate material and W or Mo as a conductor, for example, and has a porous shape. With such a configuration, the resistor 24 is a resistor having a resistance that is large to some extent and has a characteristic of easily releasing an external surge (that is, absorbing the external surge reliably). The method of manufacturing the resistor 24 will be described later.

In addition, a large number of via holes 25 in addition to the via holes 23 are provided as appropriate at portions of the alumina multilayer substrate 11 opposite to the conductor patterns of the wiring layers 16 to 20, and in these via holes 25, The conductor 26 is filled. The conductor patterns of each of the wiring layers 16 to 20 are connected by these many conductors 26. The conductor 26 is made of, for example, a conductor such as W or Mo.

On the other hand, on the lower surface of the ground pattern 22, as shown in FIG. 3, a convex portion 22a is provided so as to project downward. The protrusion dimension A of the projection 22a is, for example, about 15 to 65 μm. The ground pattern 22
The thickness dimension B of the (ie, the conductor patterns of the wiring layers 16 to 20) is, for example, about 15 μm.

As shown in FIG. 2, a resistor film 27 is provided on the upper surface of the alumina multilayer substrate 11 having such a configuration, for example, by printing and printing.
An electronic component 28 such as an IC or a bare chip is mounted on the upper surface of the alumina multilayer substrate 11 by, for example, soldering or a conductive adhesive. In FIG. 2, reference numeral "29" indicates a solder or a conductive adhesive.

Further, the alumina multilayer substrate 11 is fixed to the base 30 by, for example, bonding such that the lower surface thereof is placed on a metal base 30. The base 30 is, for example, a case for housing and fixing the alumina multilayer substrate 11. In this case, the alumina multilayer substrate 11
Adhesive between the lower surface of the base and the upper surface of the base 30.
Is filled, and the thickness of the layer of the adhesive 31 is
For example, it is about 100 μm. Therefore, the gap between the tip of the convex portion 22a of the ground pattern 22 and the upper surface of the base 30 is about 20 to 70 μm.

Next, a brief description will be given of a process of manufacturing the alumina multilayer substrate 11 having the above configuration. First, four alumina green sheets corresponding to the four alumina substrates 12 to 15 (the thickness of one green sheet is 0.1 mm).
(About 0.4 mm), and via holes 23 and 25 are formed at predetermined positions of these four green sheets.
Subsequently, a conductive paste 26 made of W, Mo, or the like is filled in the via hole 25 of the green sheet by a known method (for example, screen printing). Next, powder of alumina, powder of conductor such as W or Mo, and powder of resin (resin beads)
And a resistor paste made of a paste-like mixed material with a binder (solvent) is filled into the via hole 23 of the green sheet by a known method (for example, screen printing). The specific mixing ratio of each mixed material of the resistor paste will be described later.

Then, a printed pattern corresponding to the conductive patterns of the wiring layers 16 to 20 is formed by screen-printing a conductive paste made of W, Mo, or the like on the surface of each green sheet. Thereafter, the four green sheets are stacked, and the stacked green sheets are pressed and pressed.

Subsequently, the above four green sheets are pressed and fired at a temperature of, for example, about 1600 ° C. in a reducing atmosphere. Thus, an alumina multilayer substrate 11 as shown in FIG. 2 is manufactured. In the case of this configuration, the resistor 2
4. The conductor 26 and the substrate 11 are configured to be fired simultaneously.

Here, the specific structure of the mixed material forming the resistor 24 will be described with reference to FIGS. 1, 4, 5 and 6. FIG. First, a case will be described in which a resistor is formed by mixing a conductor such as W or Mo with alumina, that is, a resistor (resistor described in the above-mentioned publication) in which resin beads are not mixed. First, how the resistance after firing of a mixed material obtained by mixing W (tungsten) or Mo (molybdenum), which is a conductive component, and alumina is measured by the mixing ratio of the two is measured. FIG. 4 shows the results. In this case, the resistance of the mixed material after firing was measured while changing the mixing ratio of the mixed material of W and alumina (for example, the weight ratio of alumina).

From FIG. 4, it was found that when the mixing ratio of alumina was set to a predetermined value or more, the resistance value of the mixed material after firing increased rapidly and became infinite (open). The reason that the resistance value changes in this way is considered to be as follows. FIG. 5A shows a fired mixed material having a low alumina mixing ratio, and FIG. 5B shows a fired mixed material having a high alumina mixing ratio. These FIG.
As can be seen from (a) and (b), when the mixing ratio of alumina becomes equal to or more than a certain value, a portion of the conductive path of the resistor (mixed material) where electrical connection between the conductive particles (particles of W) is lost occurs. It is thought that it is. The vitreous portion shown in FIGS. 5A and 5B is formed by flowing from a green sheet during firing.

In the case of the structure shown in FIG. 5B in which the mixing ratio of alumina is large, the electrical insulation has a particle diameter of, for example, 1%.
The insulation distance is extremely small because it is secured by alumina particles and glassy material of about 3 μm. Therefore, when a high voltage such as an external surge voltage is applied, dielectric breakdown easily occurs, and the external surge passes through the resistor (mixed material). According to an experiment, it was confirmed that when an external surge was applied, the surge passed through the resistor (mixed material), and after the surge, the insulation was again secured. That is, the resistor made of the above-described mixed material has characteristics that are preferable as a discharge resistance of an external surge, specifically, has a large resistance value and a characteristic that the external surge is easily released (the external surge is easily absorbed). I understand.

Here, in the case of the graph of FIG. 4, where the resistance value suddenly becomes infinite, the weight ratio of alumina is about 50%.
% (About 50 wt%), the mixing ratio of W and alumina may be set to about 50% or more by weight of alumina. The relationship between the mixing ratio and the resistance value (ie, the graph in FIG. 4) changes depending on the type, particle size, and shape of the conductor and the particle size and shape of the alumina. It is preferable to set the optimum mixing ratio after measuring the graph of FIG.

As described above, it has been found that a resistor formed by mixing W (or a conductor such as Mo) and alumina has preferable characteristics as a discharge resistance against external surge. However, according to the present inventors, it has been found that the electric resistance of the resistor when a high voltage is applied is considerably large. For this reason, when an external surge of a large voltage is applied and flows through the resistor, there is a possibility that the calorific value of the resistor increases considerably.

Therefore, the present inventors have attempted to reduce the electric resistance of the resistor when a high voltage is applied in order to reduce the amount of heat generated by the resistor. The present inventors have invented a configuration in which the resistor 24 has a porous shape. According to the present invention, when the resistor 24 has a preferable characteristic as a discharge resistance of an external surge, the resistor 24 is applied with a high voltage. Was able to reduce the electric resistance.

More specifically, W (or a conductor such as Mo) powder is, for example, 30 wt%, and alumina powder is, for example, 70 wt%.
%, And a paste of, for example, an acrylic resin as resin beads is mixed with the paste at a mixing ratio of, for example, 30 vol% to obtain a paste-like mixed material (that is, a resistor paste). Create Then, as described above, the resistor 24 was formed by filling the resistor paste into the via hole 23 of the green sheet and baking it.

FIG. 1A shows the state of the resistor paste before firing, and FIG. 1A shows the state of the resistor 24 after firing.
(B). In FIG. 1A, reference numeral 32 indicates W particles, reference numeral 33 indicates alumina particles, and reference numeral 34.
Indicates particles of an acrylic resin. And FIG.
(B) shows that the void 35 was formed inside the resistor 24. The void 35 is formed by evaporating the acrylic particles 34 by firing.

Then, the resistor 24 (the gap 35) of this embodiment is used.
The result of measuring the magnitude of the current flowing through the resistor 24 when the voltage applied to the resistor (where the resistor exists) is changed is shown by the solid line P in FIG. On the other hand, FIG. 6 shows the result of measuring the magnitude of the current flowing through the resistor when the voltage applied to the resistor of the prior art (the resistor described in the publication having no air gap 35) is changed. Is indicated by a solid line Q. FIG. 6 clearly shows that the electrical resistance of the resistor 24 of the present embodiment is smaller than that of the conventional resistor.
The applied voltage of the resistor 24 of this embodiment is 400 V
In this case, since the current flows sufficiently in the resistor, it is understood that the resistor has a characteristic of favorably absorbing the external surge.

In this embodiment, the acrylic resin powder mixed into the resistor paste for forming the resistor 24 is
For example, polymethyl methacrylate was used. In addition, terpineol was used as a binder (solvent) for the resistor paste. In this case, the acrylic resin (polymethyl methacrylate) is a resin that is hardly soluble in the binder (terpineol). That is, as the resin beads to be mixed into the resistor paste, resin powder that is hardly soluble in the binder of the paste may be used. Also, at the time of firing, 30
Up to about 0 ° C., the resin beads need to be in a solid (volume) state, and in this regard, the acrylic resin (evaporation temperature is about 350 ° C.) is an appropriate resin. In addition, the resin is hardly soluble in the binder,
A resin other than the above-mentioned acryl may be used as long as the resin maintains a solid and liquid (volume) state up to about 0 ° C. In addition, it goes without saying that a material other than the above terpineol may be used as the binder.

According to the present embodiment having such a structure, when an external surge voltage is applied to the external input terminal pattern 21 of the alumina multilayer substrate 11, the external surge fills the via hole 23 of the alumina multilayer substrate 11. Discharge is quickly performed to the ground pattern 22 through the resistor 24. Therefore, circuit elements (for example, electronic components 28) provided on the alumina multilayer substrate 11 can be protected from the external surge.

In particular, in this embodiment, since the resistor 24 is formed in a porous shape, the electrical resistance of the resistor 24 when a high voltage is applied can be reduced. In addition, a low surge voltage can be absorbed. Therefore, even when an external surge of a large voltage is applied, the amount of heat generated by the resistor 24 can be relatively reduced. As a result, the resistor 2
It is possible to reliably prevent the conductor around 4 from being scorched and the substrate 11 from being cracked. In the above embodiment, since the resistor 24 is formed in a porous shape, the Young's modulus of the resistor 24 can be reduced, and the stress generated in the resistor 24 can be reduced.

In the present embodiment, the resistor 24 is filled in the via hole 23 provided in the alumina multilayer substrate 11 in a direction perpendicular to the plate surface.
No moisture or moisture adheres to the surface of No. 4. As a result, it is possible to prevent fluctuation of the easiness of discharging the external surge, and it is not necessary to take any special moisture proof measures. Furthermore, in the above embodiment, the minimum area that must be secured on the upper surface of the alumina multilayer substrate 11 for disposing the resistor 24 is only slightly larger than the cross-sectional area of the via hole 23. The size of the multilayer substrate 11 can be reduced.

In the above embodiment, an acrylic resin powder was added to a paste of a mixture of W powder and alumina powder in a volume of 30 V.
ol%, but the mixing ratio is not limited to 10% to 70 vol.
It has been confirmed by experiments that it can be set to about%. That is, when the mixing ratio of the acrylic resin powder is about 10 to 70 vol%, the electric resistance of the resistor when a high voltage is applied is reduced, and the resistor has a characteristic of favorably absorbing an external surge. I understood.

When the mixing ratio of the acrylic resin powder is 10
If the volume ratio is smaller than vol%, the glass component melted during the firing of the substrate infiltrates into the via hole 23, so that the void 35 is filled, and the void 35 is not formed. On the other hand, the mixing ratio of the acrylic resin powder is 70 v
In the case where it is larger than ol%, the distance between the W particles 32 becomes large, and the electric resistance of the resistor 24 becomes large on the contrary.

In the above embodiment, the resistor 24 is formed from a mixed material obtained by mixing a substrate material (alumina), a conductor and resin beads (acrylic resin). However, the present invention is not limited to this. A resistor may be formed by adding a material. A second embodiment (see FIG. 7) is shown as an example in which a resistor is formed by adding another material.

As shown in FIG. 7, in the second embodiment, a metal oxide 36 as a conductive material is interposed between the W particles 32 as conductive particles when the substrate is fired. A desired resistance value is obtained. Also in the case of this configuration, the voids 35 are formed by mixing resin beads (powder of an allyl resin). It is preferable to use a metal oxide made of a metal such as La, Y, Nb, Sc, or the like, for example, as the metal oxide 36.

Although not shown, a metal oxide which is dissolved in alumina at a high temperature (1600 ° C.) at the time of firing the substrate may be added. Also in the case of this configuration, a void is formed inside the resistor by mixing resin beads (for example, powder of an allyl resin). With such a configuration, a desired resistance value can be obtained even if many alumina particles 33 are interposed between the W particles 32.

In the first embodiment, the present invention is applied to the multilayer substrate 11 made of alumina. However, the present invention is not limited to this. For example, the present invention may be applied to a multilayer substrate made of glass ceramic. In this configuration, the glass ceramic multilayer substrate is
It can be manufactured by simultaneous firing at about 50 to 900 ° C. In this configuration, the materials constituting the resistor for external surge discharge include a glass ceramic as a substrate material and a conductor such as Ag, Ag /
It is preferable to use a mixed material in which, for example, a powder (resin beads) of an acrylic resin is mixed with a resistor paste in which Pd, Cu, Au or the like is mixed. In the glass ceramic multilayer substrate, the conductor for the wiring layer and the conductor for filling the via hole include the above Ag, Ag / Pd, Cu, A
It is preferable to use u or the like.

In the case of the above glass ceramic multilayer substrate, for example, when the substrate is fired in air, a butyl resin or a cellulose resin may be used instead of the acrylic resin. When baking the substrate in nitrogen, it is preferable to use an acrylic resin.

In the first embodiment, the via holes 2 are formed so as to penetrate the multilayer substrate 11 made of alumina.
3 is filled with the resistor 24, but the present invention is not limited to this.
A configuration may be adopted in which only a part (for example, a part corresponding to the two-layer alumina substrates 12 and 13) of 3 is filled with a resistor, and the remaining part is filled with a conductor.

FIG. 8 is a diagram showing a third embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. In the third embodiment, the present invention is applied to
7 was applied. The through-hole substrate 37 includes a substrate 38 made of alumina, and wiring layers 39 and 40 provided on the upper and lower surfaces of the substrate 38. Each of the wiring layers 39 and 40 is formed of a conductor pattern (wiring pattern) having a predetermined shape. The conductor pattern is made of a conductor such as Ag, Ag / Pd, Cu, and Au.

FIG. 8 shows the wiring layer 39 on the upper surface.
At the right end in (a), for example, an external input terminal pattern 41 is provided as an external input terminal conductor. An external input terminal (not shown) is formed on the external input terminal pattern 41. At the right end of the lower wiring layer 40 in FIG. 8A, for example, a ground pattern 42 is provided as a ground conductor.

In a portion of the substrate 38 where the external input terminal pattern 41 and the ground pattern 42 face each other, for example, a through hole 43 is formed as a hole portion on the substrate 38.
Are provided in a direction perpendicular to the plate surface. The through hole 43 is filled with a resistor 44 having a resistance value of, for example, 100 kΩ or more. Both ends (upper and lower ends) of the resistor 44 are connected to the external input terminal pattern 41 and the ground pattern 42.

The resistor 44 is made of a general thick film resistor such as a Ru-based material, a LaB _6- based material, a SnO ₂ -based material, or the like, for example, an acrylic resin powder (resin beads). And a porous material. The resistor 44 is a resistor having a large resistance value (a smaller resistance value than a resistor having a conventional configuration) and easily releasing an external surge. The resistor 44 may be made of a mixed material obtained by mixing a conductor, a resistor or glass and, for example, an acrylic resin powder (resin beads).

The wiring layers 39, 4 on the substrate 38
A large number of through-holes 45 are appropriately provided in addition to the above-mentioned through-holes 43 at portions facing the 0 conductor pattern, and the insides of these through-holes 45 are filled with conductors 46. The conductor patterns of each of the wiring layers 39 and 40 are connected by these many conductors 46. And
The conductor 46 is made of, for example, Ag, Ag / Pd, Cu, Au
And the like.

As shown in FIG. 8A, a resistor film 27 is provided on the upper and lower surfaces of the through-hole substrate 37 having such a configuration by printing and printing. Also, an IC is provided on the upper surface of the through-hole substrate 37.
And electronic components 28 such as bare chips are attached by soldering or a conductive adhesive. Further, the through-hole substrate 37 is fixed to the base 30 by, for example, bonding so that the lower surface thereof is placed on the base 30 made of metal.

Here, the through-hole board 37 having the above configuration is used.
The process of manufacturing is briefly described. First, a raw sheet-like alumina is fired to form a substrate 38. In this case, it is preferable to form through holes 43 and 45 in the substrate 38 before firing. The through holes 43 and 45 may be formed after the substrate 38 is fired.

Subsequently, the through hole 45 of the substrate 38
The inside is filled with a conductive paste made of Ag, Ag / Pd, Cu, Au or the like by a known method (for example, screen printing). In this case, as shown in FIG. 8B, the conductive paste may be printed only on the inner peripheral surface of the through hole 45 and the upper and lower opening edges to form a conductive paste layer. Next, a resistor paste made of a mixed material obtained by mixing an acrylic resin powder (resin beads) with a general thick film resistor material or the like is known in the through hole 43 for filling the resistor 44 of the substrate 38. (For example, screen printing). Also in this case, as shown in FIG. 8B, the resistor paste is printed only on the inner peripheral surface of the through hole 43 and the upper and lower opening edges to form a resistor paste layer. You may.

Then, on the upper and lower surfaces of the substrate 38, Ag, Ag
A printing pattern corresponding to the conductor pattern of the wiring layers 39 and 40 is formed by screen-printing a conductor paste made of / Pd, Cu, Au or the like. Thereafter, the substrate 38
Is fired at a temperature of about 850 ° C., for example. This allows
A through-hole board 37 as shown in FIG. 8A is manufactured.

The configuration of the third embodiment other than that described above
The configuration is the same as that of the first embodiment. Therefore, in the third embodiment, substantially the same operation and effect as in the first embodiment can be obtained. Further, the ground pattern 42 of the third embodiment may be configured such that a protrusion having the same shape as the protrusion 22a protruding from the ground pattern 22 of the first embodiment is protruded.

FIG. 9 is a diagram showing a fourth embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. In the fourth embodiment, the present invention is applied to the thick film multilayer substrate 47. The thick-film multilayer substrate 47 is formed by printing and firing the wiring layers 49 and 50 and the insulating layer 51 on the upper surface of a ceramic substrate 48 made of alumina or the like.

More specifically, first, a conductor paste is printed on the upper surface of the ceramic substrate 48 to form a print pattern corresponding to the conductor pattern of the wiring layer 49, and then the print pattern is fired. At this time, a ground pattern 49a is formed as a part of the conductor pattern of the wiring layer 49. Subsequently, an insulating paste made of, for example, glass is printed thereon to form an insulating layer 51, which is then fired. At this time, a via hole 53 for filling the resistor 52 and a via hole 55 for filling the conductor 54 are formed in the insulating layer 51.

Next, the conductive paste is filled into the via hole 55 by printing or the like, and the resistor paste is filled into the via hole 53 by printing or the like. Thereafter, the filled conductor paste and resistor paste are fired.
Here, for example, an acrylic resin powder (resin beads) is mixed in the resistor paste. This allows
The fired resistor 52 has a porous shape.
In the case of the above configuration, after the conductor paste is filled, the conductor paste is baked, and then the resistor paste is filled.
It may be configured to be fired. Moreover, after the resistor paste is filled and fired first, the conductor paste may be filled and fired.

Subsequently, after a conductive paste is printed on the upper surface of the insulating layer 51 to form a printed pattern corresponding to the conductive pattern of the wiring layer 50, the printed pattern is fired. At this time, the external input terminal pattern 50a is formed as a part of the conductor pattern of the wiring layer 50. Thus, the thick film multilayer substrate 47 is manufactured. Then, the resistor film 27 is printed and baked on the upper surface of the thick film multilayer substrate 47 manufactured as described above. In addition, the thick film multilayer substrate 4
An electronic component 28 such as an IC or a bare chip is attached to the upper surface of the base 7 by soldering or a conductive adhesive.

The configuration of the fourth embodiment other than that described above is as follows.
The configuration is the same as that of the first embodiment. Therefore, in the fourth embodiment, substantially the same operation and effect as in the first embodiment can be obtained. Also, in the case of the fourth embodiment, the operation of printing and firing the insulating paste is performed once to form the insulating layer 51.
Alternatively, the insulating layer 51 may be formed by performing the operation of printing and firing the insulating paste a plurality of times. Further, in the fourth embodiment, two wiring layers 49 and 50 and one insulating layer 51 are provided on the ceramic substrate 48, but the present invention is not limited to this.
You may comprise so that three or more wiring layers and two or more insulating layers may be provided.

FIG. 10 is a diagram showing a fifth embodiment of the present invention. The same parts as those of the first embodiment are denoted by the same reference numerals. In the fifth embodiment, when forming holes for filling the resistor in the alumina multilayer substrate 11, a plurality of via holes 56, 57, 58 and 59 are shifted in the lateral direction inside the alumina multilayer substrate 11. It was provided as follows. Then, these four via holes 56, 57, 5
8 and 59 are filled with resistors 60, 61, 62 and 63, respectively, and these four resistors 60, 61 and 6 are filled.
2, 63 were connected by conductor patterns 64, 65, 66 provided in the internal wiring layers 17, 18, 19. The upper end of the uppermost resistor 60 is connected to the external input terminal pattern 2.
1 and the lower end of the lowermost resistor 63 is connected to the ground pattern 22.

In the case of this configuration, four via holes 56,
57, 58, and 59 each constitute a partial hole. These via holes 56, 57, 58, 59
A hole (hole portion) 67 for filling the resistor is formed from. The constituent materials of the resistors 60 to 63 are the same as those of the resistor 24 of the first embodiment.

The configuration of the fifth embodiment other than that described above is the same as the configuration of the first embodiment. Therefore, in the fifth embodiment, substantially the same operation and effect as in the first embodiment can be obtained. In particular, according to the fifth embodiment, it is easy to set the position where the hole 67 for filling the resistor is formed in the ceramic multilayer substrate 11, so that the design flexibility can be increased accordingly.

In the fifth embodiment, the resistors 60 to 63 are filled in all the four via holes 56 to 59. However, the present invention is not limited to this.
At least one of the four via holes 56 to 59 may be filled with a resistor, and the remaining via holes may be filled with a conductor. In the case of this configuration, substantially the same operation and effect as those of the fifth embodiment can be obtained.

FIG. 11 is a diagram showing a sixth embodiment of the present invention. The same parts as those in the fifth embodiment shown in FIG. 10 are denoted by the same reference numerals. In the sixth embodiment, the four via holes 56 to 59, which are a plurality of partial holes, are filled.
Resistors 60-63 are connected to internal wiring layers 17, 18, 19
Are connected by the resistor patterns 68, 69, 70 provided in the first embodiment. The resistor patterns 68 and 6
9 and 70 may be formed by a similar printing method in the step of printing the conductor patterns of the internal wiring layers 17, 18 and 19. The other configuration of the sixth embodiment is the same as that of the fifth embodiment.
The configuration is the same as that of the embodiment. Therefore, in the sixth embodiment, substantially the same operation and effect as in the fifth embodiment can be obtained.

In the sixth embodiment, the resistors 60 to 63 are filled in all of the four via holes 56 to 59. However, the present invention is not limited to this. At least one of ~ 59
One may be configured so that a resistor is filled in one inside and a conductor is filled in the remaining via hole. In the case of this configuration, it is possible to obtain substantially the same operation and effect as in the sixth embodiment.

The constituent material of the substrate described in each of the above embodiments may be aluminum nitride other than alumina or glass ceramic. In this case, W, Mo, or the like can be used as the conductor material. The low antibody filled in the via hole (hole) is made of a mixed material obtained by mixing aluminum nitride as a substrate material, W or Mo as a conductor, and an acrylic resin powder as a resin bead. I did it. Thus, the resistor can be formed in a porous shape, and the resistance can be set to a favorable value, and the resistor can easily escape an external surge.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, in which (a)
FIG. 3B is a diagram illustrating a state of the resistor before firing, and FIG. 4B is a diagram illustrating a state of the resistor after firing.

FIG. 2 is an enlarged vertical sectional side view of an alumina multilayer substrate.

FIG. 3 is a partially enlarged longitudinal side view around a ground pattern.

FIG. 4 is a graph showing a relationship between a mixing ratio of a resistor (weight ratio of alumina) and a resistance value.

5A is a diagram showing a mixed material when the amount of alumina is small, and FIG. 5B is a diagram showing a mixed material when the amount of alumina is large;

FIG. 6 is a characteristic diagram showing a relationship between a voltage applied to the resistor and a current flowing through the resistor.

FIG. 7 is a view showing a mixed material according to a second embodiment of the present invention.

FIG. 8 shows a third embodiment of the present invention, in which (a)
FIG. 2 is a view corresponding to FIG. 2, and FIG.

FIG. 9 is a view corresponding to FIG. 2, showing a fourth embodiment of the present invention.

FIG. 10 is a view corresponding to FIG. 2, showing a fifth embodiment of the present invention;

FIG. 11 is a view corresponding to FIG. 10 showing a sixth embodiment of the present invention.

[Explanation of symbols]

11 is an alumina multilayer board (wiring board), 12, 13, 1
4, 15 are alumina substrates, 16, 17, 18, 19, 2
0 is a wiring layer, 21 is an external input terminal pattern (external input terminal conductor), 22 is a ground pattern (ground conductor), 22a is a convex portion, 23 is a via hole (hole portion),
24 is a resistor, 25 is a via hole, 26 is a conductor, 30 is a base, 32 is a particle of W, 33 is a particle of alumina, 34
Is an acrylic particle, 35 is a void, 37 is a through-hole substrate (wiring substrate), 38 is a substrate, 39 and 40 are wiring layers,
1 is an external input terminal pattern (external input terminal conductor),
42 is a ground pattern (conductor for ground), 43 is a through hole, 44 is a resistor, 45 is a through hole, 46
Is a conductor, 47 is a thick film multilayer board (wiring board), 48 is a ceramic substrate, 49 and 50 are wiring layers, 51 is an insulating layer, 52
Is a resistor, 53 is a via hole, 54 is a conductor, 55 is a via hole, 56, 57, 58, 59 are via holes, 60,
61, 62, 63 are resistors, 64, 65, 66 are conductor patterns, 67 is holes (holes), 68, 69, 70
Indicates a resistor pattern.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 SN // H05K 1/16 1/16 C (72) Inventor Shinji Ota 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in Denso Co., Ltd. (reference) 4E351 AA07 BB01 BB05 BB22 BB26 BB31 BB49 CC12 CC22 DD17 EE01 EE02 EE05 EE08 GG03 GG04 GG06 5E317 AA04 AA24 BB04 BB17 BB05 CD16 GG14 5E338 AA18 BB02 BB13 BB25 BB75 CC01 CC06 CC07 CD01 CD32.

Claims (6)

[Claims] 1. A wiring board comprising at least two wiring layers provided on a substrate made of alumina, glass ceramic, or the like, comprising: an external input / output terminal conductor provided on one wiring layer; and a conductor provided on the other wiring layer. A ground conductor, a hole provided in the substrate, and a resistor filled in the hole, wherein the external input / output terminal conductor is connected to the ground conductor via the resistor. Wherein the resistor is made of a mixed material mainly composed of a substrate material and a conductor, and is made porous. 2. The method according to claim 1, wherein the resistor is formed by mixing resin beads into a mixed material mainly including a substrate material and a conductor.
2. The wiring board according to claim 1, wherein the wiring board is formed by firing. 3. The method according to claim 1, wherein the resin beads include
3. The wiring board according to claim 2, wherein about 70 vol% is mixed. 4. The method according to claim 1, wherein the resin beads include 30 parts of the mixed material.
4. The wiring board according to claim 3, wherein the wiring board is mixed by vol. 5. A method of manufacturing a wiring board, comprising providing at least two wiring layers on a substrate made of alumina or glass ceramic, wherein a hole for a resistor is formed in a predetermined portion of a green sheet made of alumina or glass ceramic. A step of filling a resistor paste in which a substrate material, a conductor, and resin beads are mixed into holes for the resistors of the green sheet; and a step of printing a conductor pattern on the upper surface or the lower surface of the green sheet with the conductor paste. And a step of firing the green sheet. 6. A method of manufacturing a wiring board, comprising providing at least two wiring layers on a substrate made of alumina or glass ceramic, wherein a hole for a resistor is formed in a predetermined portion of a green sheet made of alumina or glass ceramic. A step of filling a resistor paste in which a substrate material, a conductor, and resin beads are mixed into a hole for the resistor of the green sheet; and a step of printing a conductor pattern with a conductor paste on the upper surface or the lower surface of the green sheet. And a step of laminating the green sheets; and a step of firing the green sheets.