JP2013026303A - Method of manufacturing ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a ceramic circuit board comprising a high-definition (L/S=50 μm/50 μm) electrode pattern on the ceramic substrate and having a superior joint strength between a terminal electrode and the ceramic substrate.SOLUTION: The method of manufacturing a ceramic circuit board comprises steps of: coating a receptive layer paste containing first glass ceramic powder and a first organic vehicle on the top surface of a ceramic substrate; drying the receptive paste to form a receptive layer; printing in a predetermined shape a conductive paste containing conductive powder, second glass ceramic powder and a second organic vehicle; and burning the conductive paste to form a terminal electrode, where an electrode pattern can be printed without defect such as deblurring or deformation and a high-definition electrode pattern having a small contraction percentage after firing and superior joint strength can be formed even on a poor liquid-absorbent ceramic substrate.

Description

  The present invention relates to a method for manufacturing a ceramic circuit board.

  Conventionally, a conductive paste such as Ag has been used to form terminal electrodes and circuit wiring for electrical bonding on a ceramic substrate such as an alumina substrate on which semiconductor elements, light emitting diodes, multilayer chip components, etc. are mounted. Thus, the conductor wiring is formed by film formation and firing on the ceramic substrate by a method such as screen printing.

  In Patent Document 1, in a method of manufacturing a circuit board in which a conductive pattern is formed on the upper surface of a ceramic substrate, a resin layer is provided between the ceramic substrate or its precursor substrate, and ink containing conductive particles and a dispersion medium. Thus, a technique for forming a high-definition conductive pattern with less ink sag and bleeding is disclosed.

JP 2007-84387 A

  However, in the manufacturing method of Patent Document 1, it is possible to form a figure without bleeding on the substrate surface. However, when a high-definition figure is formed by baking using a conductive paste such as Ag powder, the resin layer Since the thermal paste decomposes and disappears during the binder removal step, the conductive paste is significantly shrunk during firing, so that it is difficult to form a high-definition figure.

  In order to solve the above problems, the present invention includes a step of printing a ceramic paste comprising a first ceramic powder containing at least a glass component and a first organic vehicle on a main surface of a ceramic substrate; A step of drying an organic component contained to form a base layer containing the glass component as a main component; a conductive ceramic powder on the top surface of the base layer; a second ceramic powder containing at least a glass component; A method of manufacturing a circuit board, comprising: a step of printing a conductive paste made of an organic vehicle in a predetermined shape; and a step of baking the conductive paste to form terminal electrodes.

  According to the above manufacturing method, when the conductive paste is printed on the upper surface of the ceramic substrate, the underlying resin component absorbs moisture and can suppress dripping and blurring. The glass component contained in the ceramic paste during the baking process When the glass component contained in the conductive paste is bonded, it is possible to hold the terminal electrode with a high-definition figure. Furthermore, the circuit board excellent in the adhesive strength between a ceramic substrate and a terminal electrode can be produced by binding of a glass component.

The manufacturing process figure of the circuit board in one embodiment of the present invention 1 is a schematic cross-sectional view of a circuit board before baking an electrode according to an embodiment of the present invention. The cross-sectional schematic diagram after the electrode baking of the circuit board in one embodiment of this invention

  Hereinafter, the manufacturing method of the ceramic circuit board of this invention is demonstrated.

  FIG. 1 is a manufacturing process diagram of a circuit board according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of the circuit board before electrode baking, and FIG. 3 is a schematic cross-sectional view after electrode baking.

  As shown in FIG. 1, in the method of manufacturing a circuit board according to the present invention, first, a receiving layer paste comprising a first glass ceramic powder and a first organic vehicle is printed on a ceramic substrate 3 and dried to obtain a receiving layer. 2 dry film is formed.

  The first glass ceramic powder and the first organic vehicle used for the receiving layer 2 are not particularly limited as long as they can suppress the sagging of the conductive paste and the shrinkage during terminal electrode firing.

  Next, the conductive paste 1 made of the conductive powder, the second glass ceramic powder, and the second organic vehicle is printed on the ceramic substrate 3 in a predetermined shape on the upper surface of the receiving layer 2 after drying.

  Thereafter, a binder removal process for volatilizing the binder component contained in the receiving layer 2 and the conductive paste 1 formed on the ceramic substrate 3 is performed, and the electrode 4 and the glass layer such as the terminal electrode for mounting and the circuit wiring through the baking process. 5 is formed.

  Through such a manufacturing process, since the dried receiving layer 2 contains a resin and a glass component, a high-definition electrode pattern is produced without causing bleeding or sagging even when the conductive paste 1 is printed on the upper surface. However, if the conductive paste 1 is formed on the ceramic substrate 3 without forming the receiving layer 2, the ceramic substrate generally has poor water absorption, and bleeding and sagging occur. Here, film formation methods, such as screen printing, gravure printing, gravure offset printing, and inkjet printing, can be used for the formation method of a receiving layer paste and an electrically conductive paste.

  As the conductive powder used for electrode formation, a metal containing at least one of silver, palladium, platinum, gold, and copper can be used.

  Moreover, the adhesive strength in the interface of the ceramic substrate 3 and the electrode 4 can be improved by making the 1st glass ceramic powder into the glass material which has a predetermined softening point.

  Hereinafter, a method for manufacturing a circuit board according to the present invention will be described in detail based on examples.

  As the receiving layer paste used for Sample No. 1 in Table 1, the first organic vehicle having a resin concentration of 10 parts by weight composed of ethyl cellulose and α-terpineol, and the first glass ceramic powder are conductive. The conductive powder forming the paste was an Ag—Pd alloy, and B—Si-alkaline earth glass having a softening point lower by 90 ° C. than the sintering shrinkage start temperature of this Ag—Pd alloy. A receiving layer paste was prepared by blending 40 parts by weight of the first glass ceramic powder and 60 parts by weight of an organic vehicle. Next, the first glass ceramic powder and the first organic vehicle were mixed and dispersed to prepare a receiving layer paste. The receptor layer paste was printed on an alumina substrate by a screen printing method so that the thickness after drying was 5 μm, and then dried at 120 ° C. for 10 minutes to form a receptor layer.

  Next, as the conductive paste of the electrode, Ag—Pd alloy powder was the main component, and 12 parts by weight of the second glass ceramic powder was contained with respect to 100 parts by weight of Ag—Pd. The second glass ceramic powder is B-Si-alkaline earth glass similar to the first glass ceramic powder, but is not particularly limited. As will be described later, the shrinkage start temperature of the conductive powder. And the softening point of the glass can be selected as appropriate.

  A pattern was printed on the receiving layer after drying so that the thickness of the conductive paste after drying was 20 μm, and dried at 120 ° C. for 10 minutes to form a conductive paste. For the baking of the conductive paste, the alumina substrate, the receiving layer and the conductive paste were integrally baked in the air at 950 ° C. to form an electrode.

  Similarly, the second glass ceramic powder of sample number 2 was changed to B-Si-alkaline earth glass having a softening point 50 ° C. lower than the sintering shrinkage start temperature of the Ag—Pd alloy used for the electrode. Was the same as Sample No. 1. Sample No. 3 was the same as Sample No. 1 except that the ratio of the second glass ceramic powder to the Ag—Pd alloy powder in the conductive paste was changed to 16 parts by weight. Sample No. 4 was the same as Sample No. 1 except that the ratio of the second glass ceramic powder to the Ag-Pd alloy powder in the conductive paste was changed to 20 parts by weight.

  Next, Sample No. 5, which is a comparative example, was the same as Sample No. 1 except that no receiving layer was formed. The first glass ceramic powder of Sample No. 6 was used except that B-Si-alkaline earth glass having a softening point 110 ° C. lower than the sintering shrinkage start temperature of the Ag—Pd alloy powder used for the electrode was used. Same as Sample No. 1. The first glass ceramic powder of Sample No. 7 was used except that B-Si-alkaline earth glass having a softening point 50 ° C. higher than the sintering shrinkage start temperature of the Ag—Pd alloy powder used for the electrode was used. Same as Sample No. 1. Sample number 8 was the same as sample number 1 except that the content of the second glass ceramic powder was changed to 8%. Sample No. 9 was the same as Sample No. 1 except that the content of the second glass ceramic powder in the conductive paste was changed to 23%.

  Using the above samples, the bleeding evaluation of the conductive paste, the deposition evaluation of the plating formed on the electrode, and the adhesion strength between the ceramic substrate and the electrode were evaluated. Each evaluation method will be described.

  For the evaluation of bleeding of the conductive paste, a 18 μm, 500 mesh screen plate having a linear pattern having a L / S = 50/50 μm graphic pattern including a curved portion was used. A case where no blur was observed in the circuit pattern was indicated as “Good”, and a case where a blur of 0.01 mm or more was observed was indicated as “X”.

  In addition, a 2 mm square figure pattern evaluation sample was prepared for the fixation strength test. Film formation and baking were performed by a method in accordance with the method for forming the receiving layer and electrode, and nickel and gold plating films were formed after baking. A sample for evaluation was prepared by soldering a wire for a tensile test. By applying a tensile stress in the direction perpendicular to the substrate surface using a tensile tester (manufactured by Imada Seisakusho, tensile compression tester SV-5) at a pulling speed of 1.5 cm / min, The adhesion strength between the substrate and the electrode was measured.

  With regard to the deposition evaluation of the plating formed on the electrode, “◯” is shown when gold plating is deposited on the electrode surface, and “X” is shown when plating is not deposited.

  The ratio of the Ag—Pd alloy powder contained in the electrode shown in the example was 80:20, and TMA measurement was performed using this Ag—Pd alloy powder. As a result, the sintering shrinkage start temperature was 850 ° C. .

  The evaluation results are shown in (Table 1), (Table 2) and (Table 3) below.

  As shown in (Table 1), only the sample No. 5 of the comparative example having no receiving layer has a blur of 0.01 mm or more, and the other samples having the receiving layer have a blur of 0.01 mm or more. No results. This is because by using the receiving layer, the receiving layer absorbs the solvent component contained in the conductive paste, thereby suppressing bleeding and sagging.

  In (Table 2), the first ceramic powder having a different softening point was used to evaluate the adhesion strength between the ceramic substrate and the electrode.

  When comparing sample numbers 1 and 2 with different temperature differences between the softening point of the first glass ceramic powder and the softening point of the first glass ceramic powder and the electrode shrinkage start temperature, and sample numbers 6 and 7 of the comparative example, When the glass softening point is lower than the electrode sintering shrinkage start temperature and the temperature difference between the electrode sintering shrinkage start temperature and the first glass softening point is within 90 ° C., a high fixing strength of 26 N or more is obtained. On the other hand, when the temperature difference exceeded 90 ° C. or when the softening point of the glass was equal to or higher than the sintering start temperature of the electrode, the results were as low as 19N and 3N.

  If the temperature difference between the sintering shrinkage start temperature of the electrode and the softening point of the first glass ceramic powder exceeds 90 ° C, the shrinkage rate during the sintering of the electrode and glass during the sintering process is significantly different. On the other hand, sintering preferentially proceeds and oversintering occurs, making it difficult to maintain the electrode shape. As a result, the restraint with the substrate decreases and the bonding strength decreases. Conceivable. In addition, when the softening point of the first glass ceramic powder is equal to or higher than the sintering start temperature of the electrode, the glass flow significantly occurs prior to the diffusion of the sintering process of the conductive particles in the electrode on the ceramic substrate. It is considered that the restraint between the ceramic substrate and the conductive particles is lowered, and as a result, the bonding strength between the ceramic substrate and the electrode is lowered.

  In Sample Nos. 1, 3, and 4, as the content ratio of the second glass ceramic powder in the electrode increased to 12, 16, and 20 parts by weight, the fixing strength increased to 26, 31, and 35N. On the other hand, in the case of the glass content rate of 8 parts by weight in Comparative Example 4, the result was that the fixing strength was low as 13N.

  When the content ratio of the second glass ceramic powder in the electrode of Sample No. 9 in Table 3 was 23%, plating on the electrode fired film was not precipitated. Observation of the electrode surface of Sample No. 9 using an electron microscope revealed that a large amount of glass was deposited on the electrode surface. It is considered that plating did not form because a large amount of glass as an insulator was deposited on the surface of the Ag—Pd alloy electrode film.

  The method of manufacturing a circuit board according to the present invention has an effect in forming a high-definition conductive electrode pattern without bleeding on a ceramic substrate for mounting an IC or LED chip that is required to have a small size and high performance. It is.

DESCRIPTION OF SYMBOLS 1 Conductive paste 2 Receiving layer 3 Ceramic substrate 4 Electrode 5 Glass layer

Claims (5)

Applying a receiving layer paste comprising a first glass-ceramic powder and a first organic vehicle to the upper surface of the ceramic substrate;
Forming a receiving layer by drying the receiving layer paste; and forming a conductive paste including a conductive powder, a second glass ceramic powder, and a second organic vehicle on a top surface of the receiving layer in a predetermined shape. Printing process;
A method of manufacturing a ceramic circuit board, comprising: baking the conductive paste to form an electrode. The softening point of the glass component contained in the first glass ceramic powder is lower than the sintering start temperature of the conductive powder, and the temperature difference between the glass component and the sintering start temperature of the conductive powder is within 90 ° C. A method for manufacturing a ceramic circuit board according to claim 1. The method for manufacturing a ceramic circuit board according to claim 1, wherein the conductive paste contains 12 to 20 parts by weight of the second glass ceramic powder. The method for manufacturing a ceramic circuit board according to claim 3, wherein the conductive powder contains at least one of silver, palladium, gold, platinum, and copper. The method for producing a ceramic circuit board according to claim 4, wherein the first glass ceramic powder and the second glass ceramic powder are the same component.

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