JPH04348587A - Circuit board and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a circuit board in which adhesive strength with a glass board is enhanced and which has excellent soldering wettability even at the soldering end of an electrode and excellent weather resistance, and a method for manufacturing the same. CONSTITUTION:A glass board 1 in which conductor wirings 3 are provided on its upper surface, an electrode 3 of a first layer so formed as to be connected to the wirings 2 on the board 1, an overcoating 4 so formed as to be superposed on the peripheral edge of the electrode 3, and an electrode 5 of a second layer so formed as to be electrically connected to the upper surface of the electrode 3, are provided, and a solder layer 6 for solder-mounting other electronic components on the upper surface of the electrode 5, is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board used in electronic equipment, particularly a hybrid IC, and a method for manufacturing the same.

0002

2. Description of the Related Art FIG. 4 is a sectional view of a conventional circuit board. In FIG. 4, reference numeral 11 is a glass substrate on which conductor wiring 12 is provided. Reference numeral 13 denotes an electrode connected to the conductor wiring 12 on the glass substrate 11 and provided so that its peripheral edge overlaps the overcoat 14. 15 is a solder layer provided on the upper surface of the electrode 13.

[0003] Hereinafter, a method for manufacturing the above-mentioned conventional circuit board will be explained. First, the glass substrate 11 is ultrasonically cleaned with an alkaline cleaning agent, and then the glass substrate 11 is sufficiently dried.
A conductor wiring 12 made of copper, silver, or indium tein oxide is printed thereon and fired.

[0004] Next, either silver or copper is printed and fired to form an electrode 13 so as to be connected to a portion of the conductor wiring 12.

Next, an overcoat 14 is printed so as to overlap the peripheral edge of the electrode 13 and fired.

Finally, a solder layer 15 is provided on the upper surface of the electrode 13 to manufacture a circuit board.

[0007]

However, in the above-mentioned conventional configuration, the coefficients of thermal expansion of the solder layer 15, the electrode 13, and the glass substrate 11 are significantly different, so that the electrode 13 and the glass substrate 11 have the weakest adhesion. Stress is concentrated at the interface between the glass substrate 11 and the glass substrate 11, resulting in easy peeling and deterioration of adhesion strength with the glass substrate 11.

[0008] Furthermore, by printing and baking the overcoat 14 so as to overlap the peripheral edge of the electrode 13, the overcoat 14 penetrates into the electrode 13 and improves solder wettability on the surface of the electrode 13. This has led to problems in that the solder layer 15 is easily damaged, solder balls are easily formed, and other electronic components are easily peeled off when mounted via the solder layer 15.

The present invention solves the above-mentioned conventional problems, and provides a circuit board and its circuit board that prevents interfacial peeling by dispersing stress at the interface between an electrode and a glass substrate, and improves solderability on the electrode surface. The purpose is to provide a manufacturing method.

0010

[Means for Solving the Problems] In order to achieve this object, the circuit board of the present invention includes a glass substrate having a conductor wiring on the upper surface, and at least a copper plate connected to the conductor wiring on the glass substrate. , a first layer electrode made of a mixture of metal powder of either silver or silver-palladium and a thermosetting resin, and an overcoat formed on the substrate so as to polymerize on the peripheral edge of the first layer electrode. and a second layer electrode made of a mixture of at least a metal powder of copper, silver, or silver-palladium and a thermosetting resin so as to be electrically connected to the upper surface of the first layer electrode. , having a solder layer for soldering other electronic components on the upper surface of the second layer electrode,
The manufacturing method includes a step of printing and baking a conductor wiring on the upper surface of a glass substrate, and a step of forming a metal powder of at least copper, silver, or silver-palladium and thermosetting it to be connected to the conductor wiring. a step of forming a first layer electrode with a paste made by mixing a base resin, and a step of printing and curing an overcoat on a glass substrate so as to polymerize on the peripheral edge of the first layer electrode. , forming a second layer electrode by mixing at least a metal powder of copper, silver, or silver-palladium with a thermosetting resin so as to be electrically connected to the upper surface of the first layer electrode; and a step of forming a solder layer to solder-mount other electronic components on the upper surface of the second layer electrode.

[0011]

[Function] Therefore, according to the present invention, the electrode 2 is composed of a first layer electrode and a second layer electrode made of a mixture of metal powder of at least copper, silver, or silver-palladium and a thermosetting resin.
By creating a layered structure, stress can be absorbed by each other,
Buffer and disperse. By mixing a thermosetting resin into the first layer of electrodes on the glass substrate, the electrodes have excellent heat resistance and moisture resistance, and increase adhesion to the glass substrate.

[0012] Furthermore, since the second layer electrode, on which the solder layer is provided, has no portion that polymerizes with the overcoat, the overcoat will not be absorbed or penetrated.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a circuit board according to the present invention. In FIG. 1, 1 is a glass substrate with conductor wiring 2 on its upper surface, and a thermosetting resin is mixed with at least metal powder of copper, silver, or silver-palladium so as to be connected to the conductor wiring 2. A first layer electrode 3 is provided. Further, an overcoat 4 is provided on the glass substrate 1 so as to overlap the peripheral edge of the first layer electrode 3. 5 is the first
at least copper electrically connected to the top surface of the electrode 3 of the layer;
A second layer electrode made of a mixture of metal powder of silver or silver-palladium and a thermosetting resin, and the second layer electrode 5
A solder layer 6 on which other electronic components are soldered is provided on the top surface.

A method of manufacturing the circuit board configured as described above will be explained. First, as shown in Figure 2(a),
After the glass substrate 1 is ultrasonically cleaned with an alkaline cleaning agent, conductor wiring 2 is printed with silver on the sufficiently dried glass substrate 1 and is formed by baking.

Next, as shown in FIG. 2(b), a phenolic thermosetting silver paste (ELECTRO-SCIENCE LABO
RATORIES, INC. 1109-S) made by Co., Ltd., and heat cured at 220℃ for 2 hours.
Form the layer electrode 3. At this time, it is necessary to lower the sheet resistance of the first layer electrode 3, completely eliminate uncured parts, and eliminate changes in the resin after curing over time and thermally unstable elements. target high temperature (manufacturer's recommended temperature: 1
50°C).

Next, as shown in FIG. 2(c), an overcoat 4 is printed and cured. This is done to prevent silver migration from the silver wiring used in the conductor wiring 2.

Next, as shown in FIG. 2(d), a phenolic thermosetting copper paste is printed as a soldering electrode part so as to be electrically connected to the first layer electrode 3.
The second layer electrode 5 is formed by thermosetting at 50° C. for 30 minutes. Since the second layer electrode 5 and the first layer electrode 3 are bonded by a physical and chemical anchor effect, no electrode separation occurs at the connection interface.

Finally, as shown in FIG.
A solder layer 6 for soldering other electronic components is provided on the upper surface of the circuit board to complete the circuit board.

[0020] Also, a pressure cooker test (13
3°C, 3 atm, 5 hours) are shown in Figure 3.

As is clear from FIG. 3, the circuit board of the present invention clearly has better weather resistance than the conventional circuit board.

(Embodiment 2) A circuit board according to another embodiment of the present invention will be described below.

The configuration of the second embodiment is similar to that of the first embodiment, so the explanation will be omitted. In the manufacturing method of Example 2, as shown in FIG. 2(d) of Example 1, a phenolic thermosetting copper paste is electrically connected to the first layer electrode 3 as a soldering electrode part. Print as shown and print at a temperature of 150℃ for 30 minutes.
The second layer electrode 5 was formed by heat curing, but although the copper electrode used here has good soldering, it is easily oxidized and cannot be stored as a board for a long period of time. This was done to solve problems such as oxidation of copper electrodes on non-solder surfaces during reflow soldering. In this second embodiment, the second layer electrode 5 is made of phenolic thermosetting silver paste (ELECTRO-SC).
IENCE LABORATORIES, INC. 1110-S), which is electrically connected to the first layer electrode 3, and is thermally cured at a temperature of 150°C for 30 minutes to avoid oxidation of the electrode surface, which is the problem mentioned above. Prevented. Since the second layer electrode 5 and the first layer electrode 3 are bonded by a physical and chemical anchor effect, no electrode separation occurs at the connection interface. However, this second
The silver paste used for the electrode 5 of the layer has a higher silver content than the silver paste used for the electrode 3 of the first layer, so silver diffusion (eutectic phenomenon of silver and tin) occurs, resulting in good soldering. However, it can be improved by using solder for preventing silver diffusion (SPT73-E120-M10, manufactured by Senju Metal Industry Co., Ltd.).

[0024]

Effects of the Invention As described above, the present invention mixes a thermosetting resin with at least a metal powder of copper, silver, or silver-palladium formed to be connected to conductor wiring on a glass substrate. a first layer electrode consisting of a first layer; The two-layer structure of the electrode makes it difficult to peel off at the interface between the electrode and the glass substrate, improves the adhesion strength with the glass substrate, and provides circuit boards with excellent weather resistance and solderability. A manufacturing method can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the circuit board of the present invention.

[Fig. 2] (a) to (d) are cross-sectional views of each process showing an example of the method for manufacturing the same circuit board.

[Figure 3] Comparison diagram of weather resistance characteristics of the present invention and conventional circuit board

[
Figure 4: Cross-sectional view of a conventional circuit board

[Explanation of symbols] 1 Glass substrate 2 Conductor wiring 3 First layer electrode 4 Overcoat 5 Second layer electrode 6 Solder layer

Claims (2)

[Claims] 1. A glass substrate having conductor wiring on its upper surface, a metal powder of at least one of copper, silver, and silver-palladium formed to be connected to the conductor wiring on the glass substrate, and a thermosetting system. a first layer electrode made of a mixture of resin;
an overcoat formed on the substrate so as to overlap the peripheral edge of the first layer electrode; and at least one of copper, silver, and silver-palladium so as to be electrically connected to the upper surface of the first layer electrode. A circuit board comprising a second layer electrode made of a mixture of metal powder and thermosetting resin, and a solder layer for soldering other electronic components on the upper surface of the second layer electrode. . 2. A step of printing and baking a conductor wiring on the upper surface of a glass substrate, and thermally curing at least one of copper, silver, and silver-palladium metal powder so as to be connected to the conductor wiring. A step of printing and curing a paste made by mixing a system resin to form a first layer electrode, and printing and curing an overcoat on the glass substrate so as to polymerize on the peripheral edge of the first layer electrode. a step of forming at least copper, silver,
A step of printing and curing a paste made by mixing metal powder of either silver or palladium and a thermosetting resin to form a second layer electrode, and adding another electronic layer to the top surface of the second layer electrode. A method for manufacturing a circuit board, which includes the step of forming a solder layer for soldering components.