KR100673537B1 - A low temperature cofired ceramic on metal and method of producing the same - Google Patents

Abstract

Disclosed is a low-temperature, co-fired ceramic substrate produced by using a metal substrate as an electrical ground of a module and inserting a resistor, a capacitor, and an inductor into a multilayer ceramic circuit by screen printing. The metal phase low temperature cofired ceramic substrate according to the present invention includes a metal substrate having a ground plane formed of a conductor paste for use as an electrical ground, and a green sheet laminate having a via-hole formed on the metal substrate. In addition, the green sheet laminate is configured by charging an upper layer, a resistive layer, an inductor layer, and a capacitor layer therein. The resistor layer, the inductor layer, and the capacitor layers may be manufactured in various forms, and the via-hole of the green sheet is positioned on the ground plane of the metal substrate so that the green sheet and the metal substrate are electrically connected to each other.

Ceramic substrate, metal substrate, resistor layer, inductor layer, capacitor layer

Description

Low temperature co-fired ceramic substrate on metal and its manufacturing method {A LOW TEMPERATURE COFIRED CERAMIC ON METAL AND METHOD OF PRODUCING THE SAME}

1 is a cross-sectional view of a metal substrate having a ground plane,

2A, 2B, and 2C illustrate a green sheet printed with various types of inductor patterns;

3A and 3B are plan and cross-sectional views of a green sheet printed with a resistance;

4A, 4B, 4C, and 4D illustrate a green sheet printed with various types of capacitors;

5 is a view showing an embodiment of the arrangement of the green sheet for each layer for lamination,

6 is a cross-sectional view showing a metal-phase low-temperature fired ceramic substrate having a multilayer circuit.

<Explanation of symbols for main parts of drawing>

101: metal substrate 102: ground plane

103: glaze layer 104: adhesive layer

201: Green sheet 202,203,204: Inductor pattern

301: Resistance 302: Conductor

401: lower electrode 402: dielectric paste

403: upper electrode 404: via-hole

405,406,407,408,409: electrode 501: capacitor layer

502: inductor layer 503: resistive layer

504: upper layer 601: ceramic

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to low temperature cofired ceramic-on-metal (LTCC-M), in particular using a metal substrate as the electrical ground of the module, and by screen printing a resistor, capacitor And a low-temperature, co-fired ceramic substrate prepared by charging an inductor into a multilayer ceramic circuit.

Various types of electronic devices use interconnected integrated circuit chips in a single module or package. These multichip modules are again electrically connected to a substrate such as a PCB. For this electrical connection, the multichip modules are connected to the input / output pins of each of the input / output terminals of the module and connected to the substrate through the input / output pins.

On the other hand, in the case of a signal processing module, it is necessary to ground the circuit inside the module in order to remove the electrical noise component. For the ground processing of such a module, in the case of the LTCC module, the A ground line is formed in one layer, and the ground terminals of all circuits in the module are connected to the ground line. Alternatively, ground lines may be formed in the form of meshes in one layer of the stack (usually the lowest green sheet) for more stable grounding of the module, or in the case of LTCC-M modules, It is used as a ground terminal. However, in the above methods, when allocating a layer of the laminate to the ground, materials and processes necessary for this should be added, and since the total volume of the ground plane is much smaller than that of the metal substrate, the effect as much as the metal substrate cannot be expected. . In addition, when using a metal substrate as a ground, the process of removing a part of metal substrate oxide layer is needed.

In addition, since a circuit is conventionally formed by surface mounting of most of the resistor, the inductor, and the capacitor after firing the ceramic substrate, there are many difficulties in reducing the area of the module.

Therefore, there has been a demand for a technology of using a metal substrate itself as an electrical ground and simultaneously charging a resistor, an inductor, and a capacitor into the ceramic substrate.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to use a metal substrate as the electrical ground of the module, in order to manufacture a module substrate that operates at a high frequency in real time, by screen printing, It is to provide a metal phase low temperature cofired ceramic substrate having an inductor and a capacitor embedded in a multilayer ceramic circuit.

In order to achieve the above objects, the metal-phase low temperature cofired ceramic substrate according to the present invention is a metal substrate having a ground plane formed of a conductor paste for use as an electrical ground, and a via-hole stacked on the metal substrate. A formed green sheet laminate, wherein the green sheet laminate is composed of an upper layer, a resistive layer, an inductor layer, and a capacitor layer. In addition, a via-hole of the green sheet is positioned on the ground plane of the metal substrate so that the green sheet and the metal substrate are electrically connected to each other.

The resistance layer is formed by printing a resistance pattern on the green sheet and printing a conductor paste on both ends of the resistance pattern.

The inductor layer is formed by printing a spiral pattern, a serpentine pattern, or a three-dimensional coil pattern on the green sheet.

The capacitor layer is formed by sequentially printing the lower electrode, the dielectric paste, and the upper electrode on the green sheet, or is formed by alternately printing two electrode patterns on the green sheet, or on a pair of green sheets. Each is formed by printing an electrode pattern.

According to the present invention, by inserting a resistor, an inductor, and a capacitor into the ceramic substrate, the number of surface-mount components can be greatly reduced, and the reliability of the resistor, inductor, and capacitor components can be increased according to the sealing effect of the ceramic. It is possible to increase the component integration error per unit volume, which is advantageous in miniaturization and light weight.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

5 is a diagram illustrating an embodiment of an arrangement of green sheets for each layer for lamination.

As shown in FIG. 5, the metal-phase low temperature cofired ceramic substrate according to the present invention includes a capacitor layer 501 and an inductor layer 502 on a metal substrate 101 on which a ground plane 102 is formed using a conductor paste. ), A resistive layer 503, and an upper layer 504 are laminated in this order. The arrangement of the capacitor layer 501, the inductor layer 502, and the resistor layer 503 may be differently positioned as necessary.

In addition, in order to use the metal substrate 101 as an electrical ground of the module, the capacitor layer 501, the inductor layer 502, and the resistive layers 503 and the metals on which the respective circuit patterns are printed as described above are made of metal. A passage for electrically connecting the substrate 101 is required. The connecting passage is manufactured by printing a ground plane 102 using a conductive paste on a metal substrate before oxidation and heat-treating it in a non-oxidizing atmosphere.

The ground plane 102 heat-treated in a non-oxidizing atmosphere serves as a densified conductor film to effectively protect the nickel (Ni) layer under the conductor film during the oxidation treatment of the metal substrate 101, and the plurality of layers Via-holes formed in the 501, 502, 503 enable electrical connection with the multilayer circuit.

The characteristics of the paste to be used for the ground plane 102 should be excellent in printability on the nickel layer on the surface of the metal substrate, and should have a sufficiently dense structure after heat treatment even in a non-oxidizing atmosphere, especially during the oxidation treatment of the metal substrate 101. It should be possible to effectively protect the nickel layer below the ground plane.

In the conventional ceramic substrate, it is difficult to control the shrinkage rate, so that it is difficult to load other components in addition to the conductor. However, since the metal phase low temperature cofired ceramic substrate (LTCC-M) can suppress the surface shrinkage, the component can be easily loaded into the ceramic. That is, the resistors, inductors, and capacitors configured on the layout have the advantage of being able to be implemented in the substrate in the same size, and the thickness can be easily adjusted by screen printing conditions. Therefore, it is possible to load components with high reliability, thereby manufacturing a multilayer circuit board in which all resistors, inductors, and capacitors are loaded.

Hereinafter, a method of manufacturing a ceramic substrate according to an embodiment of the present invention will be described in detail.

1 is a cross-sectional view of a metal substrate having a ground plane formed thereon.

First, in order to use the metal substrate itself as the electrical ground of the module, a ground plane must be formed on the metal substrate. The process is as follows.

The Cu / Ni or Ni layer is coated on the metal substrate 101 by one of cladding, plating, and diffusion binding, and then cut into a desired size. After removing impurities present on the surface of the metal substrate using an organic solvent, a paste made of Ag or Ag / Pd is printed on the prepared substrate using a screen printer in a desired pattern. The substrate is placed in a kiln in a non-oxidizing atmosphere to densify the printed paste. In order to provide a non-oxidizing atmosphere, gas flows such as N ₂ and Ar may be used. At this time, the densified paste serves as a passage for electrically connecting the multilayer ceramic circuit board and the metal substrate in the final module. Thereafter, the metal substrate is oxidized, the glaze layer 103 is formed on the oxide layer, and the adhesive layer 104 is printed on the surface of the glaze layer 103 to complete the metal substrate 101.

In order to form a multilayer circuit, the green sheet is cut to a desired dimension, a via-hole is formed using a puncher, and then the conductive paste is filled into the via-hole. The via-hole serves to connect the interlayer circuits. The green sheet filled with via-holes is printed with a circuit pattern suitable for each layer. In this case, a via-hole is formed in the green sheet of the portion that is connected to the metal substrate, and thus, the green sheet may be electrically connected to the metal substrate. Therefore, the circuit is configured such that the via-hole is located on the ground plane 102 of the metal substrate 101.

2A, 2B, and 2C illustrate a green sheet on which various types of inductor patterns are printed.

In FIG. 2A, a spiral inductor pattern 202 is printed on the green sheet 201 using a conductor paste. In FIG. 2B, a tortuous inductor pattern 203 is printed on the green sheet 201. In FIG. 2C, a three-dimensional inductor pattern 204 formed by lamination of the green sheet 201 was printed. The interlayer coil of the three-dimensional inductor pattern 204 is connected through the via-hole 205. These various inductor patterns are selected and used as needed.

3A and 3B are a plan view and a sectional view of a green sheet printed with a resistor.

As shown in Figs. 3A and 3B, the resistive layer is made by printing the resistor 301 paste and the conductor 302 paste for forming the electrodes on the green sheet. Such a resistive layer can be easily adjusted to have various values depending on the composition of the resist and conductor paste and the area and thickness to be printed.

4A, 4B, 4C, and 4D illustrate green sheets on which various types of capacitors are printed.

4A shows a method of printing a flat capacitor on a green sheet using a dielectric paste 402. First, the lower electrode 401 is printed by using a conductor paste, and the dielectric paste 402 is printed on the lower electrode 401 after drying. The dielectric is printed by adjusting the size or thickness of the dielectric to obtain the desired capacitance. After drying, a capacitor is made by printing the upper electrode 403. In this case, the via-hole 404 is connected to the upper electrode 403 and the lower electrode 401 to be connected to the multilayer circuits. Capacitors fabricated in this way can be used in cases where high capacitance, which is difficult to obtain with the ceramic substrate material itself, is required.

FIG. 4B is a method using the dielectric constant of the ceramic substrate itself, and may be used when very low capacitance is required. When two electrodes 405 made of a conductor paste are alternately printed on the green sheet 201 with a plurality of low-capacitances, Low capacitance capacitors are made easily.

4C is a capacitor using the thickness of the green sheet, which can be made by printing and stacking the electrodes 406 and 407 on two green sheets 201.

4D is a capacitor using the green sheet thickness by using the electrode 408 printed on the green sheet 201 as the upper electrode of the capacitor and the ground plane of the metal substrate 101 as the lower electrode 409.

The printed patterns as above are dried in an oven to complete the circuit.

As shown in FIG. 5, after the printed green sheet is dried, the green sheet forming the layers 501, 502, 503, which is filled with a resistor, an inductor, and a capacitor into each of the layers 501, 502, 503 is press-laminated at a temperature of 80 to 100 ° C. to form one molded body. Make it. This is placed on the prepared metal substrate 101 and pressurized again so that the green sheet laminate is attached onto the metal substrate 101.

6 is a cross-sectional view showing a metal-phase low-temperature fired ceramic substrate having a multilayer circuit.

As shown in FIG. 6, when the metal substrate 101 and the green sheet laminate 601 attached thereon are fired at a temperature of 850 to 900 ° C., a resistor, an inductor, and a capacitor are formed in the ceramic. The low-temperature, co-fired ceramic substrate (LTCC-M) electrically connected to the multilayer ceramic substrate and the metal substrate through the ground plane is completed.

The circuit pattern can be again formed on the baked LTCC-M substrate through post-processing, and the LTCC-M module of the desired purpose can be finally realized through the bonding of the surface mount components and the IC attachment.

As mentioned above, the use of an additional green sheet to form ground by using the metal substrate itself of the LTCC-M module according to the invention as the electrical ground and loading resistors, inductors and capacitors into the multilayer ceramic circuitry. It is economical because there is no need for the process, and the number of surface mount components can be drastically reduced, and the size and thickness of resistors, inductors, and capacitor patterns can be easily adjusted, and various component values can be easily realized. According to the ring effect, the reliability of components such as resistors, inductors, and capacitors can be increased, and the degree of component integration per unit volume can be increased, which is advantageous in miniaturization and weight reduction.

In addition, although the present invention has been described in detail with reference to the embodiments described above, the present invention is not limited thereto, and modifications and improvements are possible within the scope of ordinary knowledge of those skilled in the art.

Claims (6)

A metal substrate having a ground plane formed of a conductor paste for use as an electrical ground; And A green sheet laminate stacked on the metal substrate and having via-holes formed therein; The green sheet laminate is a metal phase low temperature cofired ceramic substrate, characterized in that consisting of a top layer, a resistive layer, an inductor layer, and a capacitor layer. The metal-phase low temperature cofired ceramic substrate of claim 1, wherein a via-hole of the green sheet is positioned on a ground surface of the metal substrate so that the green sheet and the metal substrate are electrically connected to each other. The metal-phase low temperature cofired ceramic substrate of claim 1, wherein the resistance layer is formed by printing a resistance pattern on a green sheet, and printing a conductor paste on both ends of the resistance pattern. The low temperature metal phase of claim 1, wherein the inductor layer is printed in a spiral pattern on the green sheet, a serpentine pattern on the green sheet, or printed in a three-dimensional coil pattern. Ground plane forming method of co-fired ceramic substrate. The method of claim 1, wherein the capacitor layer is formed by sequentially printing the lower electrode, the dielectric paste, and the upper electrode on the green sheet, or is formed by alternately printing a plurality of two electrode patterns on the green sheet, or the capacitor layer is A low-temperature, co-fired ceramic substrate, characterized in that formed by printing an electrode pattern on a pair of green sheets, respectively. delete

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