JPH05291755A - Ceramic multilayer circuit board and multichip module using it - Google Patents

Abstract

PURPOSE:To get a ceramic multilayer circuit, which has a highly accurate thick film resistor within, by equalizing the distribution of Ag inside the built-in resistor. CONSTITUTION:In a ceramic multilayer circuit board, where a thick resistor 3 is arranged between the layers of the ceramic board and the thick resistor is electrically connected by Ag or a conductor material 1 partially including Ag, the ratio of the concentration of Ag within the thick resistor in the section 10mum apart from the interface between the thick resistor 3 made inside the ceramic board and the electrode constituted of a conductor material 1 to the concentration of Ag within the thick film resistor in the section most part from the electrode is two or less. This is a thick resistor, where the average concentration of Ag within itself is not more than 0.2wt. or not less than 1.5wt.%, within the board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic multi-layer circuit board, and more particularly to a high-density ceramic multi-layer circuit board with a built-in high-precision resistor element and a multi-chip module using the same.

[0002]

2. Description of the Related Art Recent hybrid ICs are smaller,
Due to the demand for high density, an electrode pattern is formed by printing on a green sheet, and these are laminated and sintered, or a wiring pattern is formed inside the substrate obtained by multilayering and sintering by repeating screen printing. Ceramic multi-layer circuit boards have been used. However, as circuits to be formed inside the substrate, technological development is being promoted that includes not only conductor wiring but also passive elements such as resistors that are conventionally mounted on the surface of the substrate. As one of them, there is a technique disclosed in JP-A-2-5448. That is, by incorporating a resistor between the layers of the board, a higher density multilayer circuit board is realized.

[0003]

However, according to the conventional techniques, when an attempt is made to include a resistor inside the substrate, the relationship between the resistor length and the resistance value largely deviates from the linear relationship, and an arbitrary resistance value is obtained. It is extremely difficult to design the shape of the resistor, and it is difficult to incorporate the resistor with high precision. The present invention solves these problems, and provides a ceramics multilayer circuit board including a highly accurate thick film resistor in which a linear relationship between a resistor length and a resistance value can be easily obtained, and a multichip module using the same. The purpose is to

[0004]

In order to achieve the above object, according to the present invention, a thick film resistor is arranged between layers of a ceramic substrate, and the thick film resistor is made of Ag or a conductor material partially containing Ag. In a ceramic multilayer circuit board electrically connected, in the thick film resistor in a portion where the distance from the interface between the thick film resistor formed inside the ceramic substrate and the electrode made of the conductive material is 10 μm The ratio of the Ag concentration in the thick film resistor to the Ag concentration in the thick film resistor in the portion farthest from the electrode is within 2 times. And a ceramic multi-layer circuit board having a highly accurate thick film resistor inside the substrate, which makes it possible to easily obtain a proportional relationship between the resistance value and the resistance value. In the ceramic multilayer circuit board, the thick film resistor formed inside the ceramic substrate has an average Ag concentration of 0.
By setting the content to 2 wt% or less, or 1.5 wt% or more, it is possible to obtain a ceramics multilayer circuit board having a highly accurate thick film resistor in which the proportional relationship between the resistor length and the resistance value can be easily obtained. ..

In the ceramic multilayer circuit board,
In order to reduce the average concentration of Ag in the thick film resistor to 0.2 wt% or less, a noble metal-based terminal other than Ag is used so as not to directly contact the thick film resistor with Ag or the conductor partially containing Ag. In the degreasing step, which is obtained by connecting the substrates in the ceramic multi-layer circuit board, and by performing the degreasing step in an atmosphere containing oxygen at least twice the oxygen concentration in the atmosphere, Is obtained even if the residual carbon amount of 0.005 wt% or less,
By doing so, it is possible to realize a ceramics multilayer circuit board having a highly accurate thick film resistor in which the proportional relationship between the resistor length and the resistance value can be easily obtained.

The average concentration of Ag in the thick film resistor can be set to 0.2 wt% or less by setting the concentration of Ag in the conductive material to 50 wt% or less.
By doing so, it is possible to realize a ceramics multilayer circuit board having a highly accurate thick film resistor in which the proportional relationship between the resistor length and the resistance value can be easily obtained. The multi-layer circuit board obtained by the present invention can be used as a termination resistor in a high-frequency compatible multi-chip module equipped with a large number of chips and a termination resistor, and is small in size and high in density, and is a portable camera-integrated video device. In addition, it can be effectively used as an electronic circuit board constituting electronic equipment for mobile communication, telephone exchanges, workstations, personal computers, word processors, telephone exchanges, and the like.

[0007]

In the prior art, the relationship between the resistance length and the resistance value deviates greatly from the linear relationship because the Ag from the electrode
This is due to diffusion into the resistor. FIG. 2 shows the Ag concentration ratio (the distance from the interface with the electrode is 10 μm) for a resistor having a resistor length of 0.3 mm to 3 mm, which is a practical resistor.
It is a plot of the maximum value of the ratio (Ag amount ratio of the portion m and the portion farthest away) against the Ag concentration in the resistor. As can be seen from FIG. 2, there are two methods for reducing the concentration gradient: decreasing the average concentration of Ag or increasing it. In particular, for the resistor in the practical range, in order to satisfy the condition of claim 1, the Ag concentration is 0.2 w.
It should be t% or less or 1.5 wt% or more.

In the prior art, since the resistor is formed in contact with the Ag-based conductor, Ag in the conductor diffuses into the resistor. Then, the Ag concentration is high in the vicinity of the conductor, and the Ag concentration is low in the place away from the conductor. That is, the Ag concentration in the resistor becomes non-uniform. However, although the resistor formed on the surface layer is also in direct contact with the Ag-based conductor, such a problem does not occur. This is related to the mechanism of Ag diffusion. Thick film paste and green sheets are a mixture of organic and inorganic substances, and they form conductors, resistors, insulation layers, etc. by firing, but if organic substances are not degreased during firing, residual carbon will be present in the resistors. Become. A
The diffusion of g is greatly accelerated by the presence of residual carbon in and near the resistor. In the case of the surface layer resistor, since it is in direct contact with air, it is sufficiently degreased, the amount of residual carbon is small, and the diffusion of Ag is not a big problem. However, degreasing is insufficient in the resistor formed inside the substrate, a large amount of residual carbon is present, and Ag diffusion seriously affects the resistance value.

In order to make the Ag concentration in the resistor uniform, it is sufficient to suppress the diffusion of Ag from the electrodes. For that purpose, by devising the structure of the contact portion of the conductor and the resistor, Ag
Can be suppressed from diffusing into the resistor. Alternatively, by reducing the amount of residual carbon in the substrate, it is possible to suppress the diffusion of Ag into the resistor. In this case, whichever method is used, as a result, the Ag concentration in the resistor becomes extremely small, and the concentration gradient of Ag in the resistor can be made extremely small. That is, the average Ag concentration in the thick film resistor is set to 0.2 wt% or less, and the thick film resistor is located at a distance of 10 μm from the interface between the thick film resistor and the electrode made of the conductive material. It is possible to set the ratio of the Ag concentration in the body to the Ag concentration in the thick film resistor at the portion farthest from the electrode to within 2 times. With a resistor satisfying this condition, a linear relationship between the resistor length and the resistance value can be easily obtained. That is,
Hybrid IC with high precision thick film resistor inside
It is possible to realize a multilayer circuit board.

Further, by increasing the Ag concentration in the resistance paste in advance, the Ag from the electrode to the resistor is increased.
The driving force for the diffusion of Ag can be reduced and the diffusion of Ag can be suppressed. In this case, the concentration of Ag in the resistor is generally high, and as a result, the concentration gradient is suppressed. Ag in resistance paste
The method of increasing the concentration is to add Ag to the resistance paste.
Just mix the powders. Or, if Ag is dissolved in the resistance paste glass near the saturation concentration in advance,
The dissolution of Ag from the electrode to the resistor is suppressed, and the concentration gradient of Ag, which is an unstable element of the resistance value, is suppressed to a small value. That is, the thick film resistor has an average Ag concentration of 1.5 wt% or more and a distance of 10 μm from the interface between the thick film resistor and an electrode made of a conductive material. It is possible to set the ratio of the average Ag concentration in the body to the Ag concentration in the thick film resistor in the portion farthest from the electrode to within 2 times. With a resistor satisfying this condition, a linear relationship between the resistor length and the resistance value can be easily obtained. That is, it is possible to realize a multi-layer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside.

The above invention will be specifically described. First, the structure of the electrode / resistor contact portion will be described. Since the diffusion of Ag occurs because the electrode and the resistor are in direct contact, more specifically, a terminal 2 is provided between the electrode 1 and the resistor 3 as shown in FIG. Do not directly contact the electrodes including. The material for this terminal is Au, Pt,
Pd and the like are preferable. This prevents Ag diffusion. That is, the average Ag concentration in the thick film resistor is 0.2 w
t% or less, and at a portion where the distance from the interface between the thick film resistor and the electrode made of a conductive material is 10 μm, the Ag concentration in the thick film resistor and the portion farthest from the electrode It is possible to make the ratio with the concentration of Ag in the thick film resistor within twice. With a resistor satisfying this condition, a linear relationship between the resistor length and the resistance value can be easily obtained. That is, it is possible to realize a multi-layer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside.

[0012] Next, regarding the mechanism of Ag diffusion mechanism, since residual carbon promotes Ag diffusion, it is possible to prevent Ag diffusion by reducing the amount of residual carbon as much as possible. More specifically, if the oxygen concentration at the time of degreasing the substrate is set to be at least twice the oxygen concentration in the atmosphere, the residual carbon amount in the substrate becomes 0.005 wt% or less, and Ag diffusion can be suppressed. That is, the average Ag concentration in the thick film resistor is set to 0.2 wt% or less, and the thick film resistor is located at a distance of 10 μm from the interface between the thick film resistor and the electrode made of the conductive material. Ag in the body
It is possible to set the ratio of the concentration of Ag to the concentration of Ag in the thick film resistor in the portion farthest from the electrode within 2 times. With a resistor satisfying this condition, a linear relationship between the resistor length and the resistance value can be easily obtained. That is, it is possible to realize a multi-layer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside.

The diffusion of Ag can also be suppressed by lowering the Ag concentration in the conductor material. Specifically, when the Ag concentration in the conductor material is 50 wt% or less, Ag diffusion can be suppressed. That is, the average Ag concentration in the thick film resistor is set to 0.2 wt% or less, and the thick film resistor is located at a distance of 10 μm from the interface between the thick film resistor and the electrode made of the conductive material. Ag concentration in the body and Ag in the thick film resistor at the part farthest from the electrodes
It is possible to make the ratio with the concentration of 2 or less. With a resistor satisfying this condition, a linear relationship between the resistor length and the resistance value can be easily obtained. That is, it is possible to realize a multi-layer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside.

[0014]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited thereto. Embodiment 1 FIG. 1 shows an embodiment of the present invention. This figure shows a cross-sectional view of a multilayer circuit board / resistor connection portion according to the present invention.
First, an organic solvent such as polyvinyl butyral was added to lead borosilicate glass powder and alumina powder serving as a frit, and the mixture was stirred to form a sludge. A plurality of unfired dielectric green sheets were formed from this slurry by a casting film forming method using a doctor blade. Next, the outer shape and a plurality of holes (via holes) were formed by punching at the same time with a mold made of stainless steel or the like. First, a conductor paste containing Ag or the like as a main component was applied to the green sheet to fill the via holes. Next, a conductor paste containing gold or the like as a main component was also screen-printed to form the terminal 2. Next, a conductor paste containing Ag as a main component was also screen-printed to form a conductor 1. Next, a resistance paste containing ruthenium oxide and glass as main components was applied by a screen printing method to form a resistor 3. A plurality of similarly formed green sheets are used to sequentially stack.

Then, using a heat press or the like, a temperature of 12
Thermocompression bonding was performed from the upper and lower surfaces under the conditions of 0 ° C. and a pressure of 200 kg / cm ² to obtain a laminate. This molded body was placed in air at a temperature of 3
After degreasing at 50 ° C for about 1 hour, still in air at 850 ° C
By firing for about 10 minutes, it was possible to obtain a thick film resistor having an average Ag concentration of 0.1 wt% in the thick film resistor. At this time, the relationship between the resistor length and the resistance value was close to a linear relationship, and the resistance value variation was 8 wt% or less. In other words, it was possible to realize a multilayer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside. However, using the conventional technique, the average Ag concentration in the thick film resistor is 0.2 wt.
%, And the concentration of Ag in the thick film resistor at a portion at a distance of 10 μm from the interface between the thick film resistor and the electrode made of a conductive material and the portion farthest from the electrode. When the characteristics of the ceramic multi-layered substrate containing the thick film resistor that exceeds the ratio of the concentration of Ag in the thick film resistor is more than doubled and the characteristics are investigated, the relation between the resistor length and the resistance value is linear. And the resistance variation was 20% or more.

Example 2 A dielectric green sheet was produced in the same manner as in Example 1. Next, the outer shape and a plurality of holes (via holes) were formed by punching at the same time with a mold made of stainless steel or the like. First, a conductor paste containing Ag or the like as a main component is applied to the green sheet to fill the via holes. Next, a conductor paste containing Ag as a main component is similarly screen-printed to form the conductor 2. Next, a resistor paste containing ruthenium oxide and glass as a main component and containing 1.8 wt% of Ag powder was applied by a screen printing method to form a resistor 3
Formed. Here, unlike Example 1, the resistor and the conductor were formed in contact with each other. A plurality of similarly formed green sheets were used and sequentially stacked. Then, using a hot press or the like, thermocompression bonding was performed from the upper and lower surfaces under the conditions of a temperature of 120 ° C. and a pressure of 200 kgf / cm ² to obtain a laminate.

The molded body was degreased in air at a temperature of 350 ° C. for about 1 hour and then baked in air at 850 ° C. for about 10 minutes, so that the average Ag concentration in the thick film resistor was 1.8 wt.
%, And the Ag concentration in the thick film resistor at a portion where the distance from the interface between the thick film resistor and the electrode made of a conductive material is 10 μm and the thick film at the portion farthest from the electrode. A thick film resistor having a ratio of 1.4 times the Ag concentration in the resistor could be obtained. At this time, the relationship between the resistor length and the resistance value was close to a linear relationship, and the resistance value variation was 8% or less. In other words, it was possible to realize a multilayer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside. However, using the conventional technique, the average Ag concentration in the thick film resistor is less than 1.5 wt%, and the distance from the interface between the thick film resistor and the electrode made of the conductive material is 10 μm. Of the thick film resistor in which the ratio of the concentration of Ag in the thick film resistor in the portion of [1] to the concentration of Ag in the thick film resistor in the portion farthest from the electrode exceeds twice, When the substrate was manufactured and the characteristics were examined, the relationship between the resistor length and the resistance value was
It deviated from the linear relationship, and the variation in resistance value became 20% or more.

Example 3 A dielectric green sheet was produced in the same manner as in Example 1. Next, the outer shape and a plurality of holes (via holes) were formed by punching at the same time with a mold made of stainless steel or the like. First, a conductor paste containing Ag or the like as a main component was applied to the green sheet to fill the via holes. Next, a conductor paste containing Ag as a main component was screen-printed to form a conductor 2. Next, a resistance paste mainly composed of ruthenium oxide and glass was applied by a screen printing method to form a resistor 3. Example 1 here
Unlike the resistor and the conductor were formed in contact with each other. A plurality of similarly formed green sheets were used and sequentially stacked. Then, using a heat press or the like, the temperature is 120 ° C. and the pressure is 200.
A laminate was obtained by thermocompression bonding from the upper and lower surfaces under the condition of kgf / cm ² .

This molded product was subjected to an oxygen concentration of 55% and a temperature of 35.
After degreasing at 0 ° C for about 1 hour, the amount of residual carbon in the substrate is 0.0 by baking at 850 ° C for about 10 minutes in air.
02 wt% and the average Ag concentration in the thick film resistor is 0.
The concentration of Ag in the thick film resistor is 16 wt% and the distance from the interface between the thick film resistor and the electrode made of a conductive material is 10 μm. A thick film resistor having a ratio with the concentration of Ag in the thick film resistor of 1.7 times could be obtained. At this time, the relationship between the resistor length and the resistance value was close to a linear relationship, and the resistance value variation was 8% or less. In other words, it was possible to realize a multilayer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside. However, degreasing is performed in an atmosphere in which the oxygen concentration is lower than twice that in the atmosphere, and the average Ag concentration in the thick film resistor is set to 0.50 by using the conventional technique in which the residual carbon amount in the substrate exceeds 0.005 wt%. The concentration of Ag in the thick film resistor at a portion exceeding 2 wt% and the distance from the interface between the thick film resistor and the electrode made of a conductive material being 10 μm and the portion farthest from the electrode A ceramic multilayer substrate having a thick film resistor whose ratio to the Ag concentration in the thick film resistor exceeds 2 times was manufactured and its characteristics were examined. The relationship between the resistor length and the resistance value was found to be linear. It was out of the relationship, and the resistance variation was 20% or more.

Example 4 A dielectric green sheet was produced in the same manner as in Example 1. Next, the outer shape and a plurality of holes (via holes) were formed by punching at the same time with a mold made of stainless steel or the like. First, a conductor paste containing Ag or the like as a main component was applied to the green sheet to fill the via holes. Next, a conductor paste having a metal component ratio of Ag 50 wt% and Pd 50 wt% was screen-printed to form a conductor 2. Next, a resistance paste mainly composed of ruthenium oxide and glass was applied by a screen printing method to form a resistor 3. Here, unlike Example 1, the resistor and the conductor were formed in contact with each other. A plurality of similarly formed green sheets were used and sequentially stacked. Then, using a hot press or the like, thermocompression bonding was performed from the upper and lower surfaces under the conditions of a temperature of 120 ° C. and a pressure of 200 kgf / cm ² , to obtain a laminate.

The molded body was degreased in the air at a temperature of 350 ° C. for about 1 hour and then baked in air at 850 ° C. for about 10 minutes, so that the average Ag concentration in the thick film resistor was 0.12 wt%.
And in the portion where the distance from the interface between the thick film resistor and the electrode made of a conductive material is 10 μm, the Ag concentration in the thick film resistor and the portion farthest from the electrode A thick film resistor having a ratio to the Ag concentration in the thick film resistor of 1.5 times could be obtained. At this time, the relationship between the resistor length and the resistance value was close to a linear relationship, and the resistance value variation was 8% or less. In other words, it was possible to realize a multilayer circuit board for a hybrid IC that includes a highly accurate thick film resistor inside. However, using a conventional technique in which the average Ag concentration in the conductor exceeds 60 wt%, the average Ag concentration in the thick film resistor exceeds 0.2 wt% and the thick film resistor and the conductor material are used. The ratio of the concentration of Ag in the thick film resistor at a portion at a distance of 10 μm from the interface with the electrode to the concentration of Ag in the thick film resistor at the portion farthest from the electrode is doubled. When a ceramic multi-layered substrate including a thick film resistor exceeding 100 μm was manufactured and its characteristics were examined, the relation between the resistor length and the resistance value deviated from the linear relation, and the resistance value variation was 2
It has exceeded 0%.

Example 5 The following two types of high-frequency compatible multi-chip modules were prepared, each having 7 QFPs of 10 mm □, 40 chip parts having an average size of mm □, and 80 terminating resistors. A terminating resistor formed on the surface. A terminating resistor is formed inside the substrate by the method of the second embodiment. In the case of, the substrate area was 1400 mm ² . In this case, since the area required to mount the terminating resistor is reduced, the substrate area was reduced to 1250 mm ² . In the high frequency multi-chip module, the signal transmission speed is important, and therefore the shorter wiring length is preferable. In order to shorten the wiring length, it is preferable that the substrate is small. That is, the multi-chip module manufactured by the method has the excellent characteristic that the signal transmission delay is small.

[0023]

According to the present invention, by reducing the concentration gradient of Ag of the resistor in the ceramic substrate, a resistor having a resistance value and a resistance length close to a linear relationship and having a high accuracy is built in. A ceramic multilayer circuit board was obtained. In addition, the multilayer circuit board can be provided for various uses.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a multilayer circuit board according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the Ag content in a resistor and the resistance value.

[Explanation of symbols]

1: Ag-based conductor, 2: Terminal, 3: Resistor, 4: Green sheet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location H01L 23/15 H05K 3/46 H 6921-4E S 6921-4E (72) Inventor Tadada Asai Ibaraki Prefecture 4026 Kuji-machi, Hitachi City, inside Hitate Works Co., Ltd. (72) Noritaka Kamimura 4026, Kuji-cho, Hitachi City, Ibaraki Prefecture Hitate Works Co., Ltd.

Claims (7)

[Claims] 1. A ceramic multilayer circuit board in which a thick film resistor is arranged between layers of a ceramic substrate, and the thick film resistor is electrically connected by Ag or a conductor material containing a part of Ag, in the ceramic substrate. A in the thick film resistor at a distance of 10 μm from the interface between the thick film resistor formed on the substrate and the electrode made of the conductive material.
A ceramics multilayer circuit board having a thick film resistor in which the ratio of the concentration of g and the concentration of Ag in the thick film resistor in the portion farthest from the electrode is within 2 times. .. 2. The thick film resistor formed inside the ceramic substrate has an average Ag concentration of 0.
The ceramic multilayer circuit board according to claim 1, wherein the content is 2 wt% or less. 3. The thick film resistor formed inside the ceramic substrate has an average Ag concentration of 1.
The ceramic multilayer circuit board according to claim 1, wherein the content is 5 wt% or more. 4. The ceramic multilayer circuit board according to claim 2, wherein the thick film resistor is connected to the conductor containing Ag or a part of Ag through a noble metal-based terminal other than Ag. .. 5. The ceramic multilayer circuit board according to claim 2, wherein the conductor material partially containing Ag has an Ag concentration of 50 wt% or less in the conductor material. 6. The ceramic multilayer circuit board according to claim 2, wherein the residual carbon amount in the ceramic multilayer circuit board is 0.005 wt% or less. 7. A high frequency compatible multi-chip module, comprising a large number of chips and a terminating resistor, wherein the ceramic multilayer circuit board according to claim 1, 2 or 3 is used as the terminating resistor. module.