JPS58186996A - Method of producing multilayer circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ninth method for manufacturing a multilayer circuit board on which a large number of active elements and passive elements such as 1G, capacitors, and resistors are mounted.

Conventionally, when forming an insulating layer to insulate between the multilayer conductor circuits of this type of multilayer circuit board by screen printing, a via hole shape was formed on the screen due to the influence of the circuit conductor existing as the base. It was difficult to print the entire pattern. In addition, the recent need for high-density multilayer circuit boards for high-speed calculations requires insulating layer materials to have physical properties such as low specific electric current, high thermal conductivity, and large mechanical *f. A mixture of glass powder and inorganic oxide powder such as aluminum is used.

Therefore, the insulating layer after formation contains many pores.If there are many pores, the plating solution will seep in during the plating process, metal will precipitate, and this will cause a short circuit between the upper and lower conductor layers, deteriorating the insulation properties. The present invention eliminates the above drawbacks, prevents deterioration of insulation properties by reducing pores, enlarges mechanical equipment, secures via holes, and secures connections with upper and lower layer conductors. The method of manufacturing a multilayer circuit board of the present invention includes a process of forming an Ill conductor pattern on a ceramic substrate, and a process of forming an Ill conductor pattern on a ceramic substrate, and a process using a high melting point glass powder and an inorganic A collection consisting of oxide powder
A layer of insulating paste is formed on the ceramic substrate including the conductor pattern using an insulating paste and a screen having a pattern for forming holes, and a layer of insulating paste is formed between the softening point and the melting point of the high melting point glass powder. The exposed part of the I11 conductive pattern and the insulating layer are coated with a wire insulating paste containing low melting point glass powder, which is fired at a high temperature to form the insulating layer. a step of forming a second insulating layer by firing at a temperature slightly higher than the softening point of the melting point glass; forming a third paste coating layer having a pattern consistent with the pattern of the ill insulating layer, and firing at a temperature between the softening point and the melting point of the high melting point glass in the wJ1 insulating paste to form a third insulating layer; It consists of a process.

Next, embodiments of the present invention will be described using the drawings.

Figures m1 to W and 6 are cross-sectional views of main manufacturing steps for explaining an embodiment of the present invention.

First, as raw materials, a ceramic substrate made of alumina etc., a thick film conductor forming paste containing Au, A4/Pd (containing precious metals), all glass powder with a softening point of 800 degrees Celsius and a melting point of 1000 degrees Celsius, and Aluna powder. A first insulating paste containing a glass powder having a softening point of 500°C and a melting point of 850°C is prepared.

Next, as shown in Figure I@1, a thick film forming paste t11! is placed on the ceramic substrate l! A conductor pattern 2 is formed using a screen printing method. On top of this, IIII insulation paste was printed using the screen printing method, dried, and assembled.
An insulating paste coating layer 3 is formed. At this time, the screen has a two-wire conductor pattern wt1 that will be formed in a later process.
4T3 Use the one having the ninth via hole 7 to be connected to the conductor pern 2〇Next, as shown in figure s'l'12, apply the sjl 1 insulating paste coating layer 3 together with the substrate l. IEI by firing at 850℃
An insulating layer 4 is formed. This firing generates a large number of pores 5 in the Ml-free layer 4.

Next, as shown in FIG. 3, a strand of 2φ insulating paste is applied to the entire surface and fired at 530° C. to fill the via hole 7 and form a 9312 insulating layer 6.

Next, as shown in FIG. 4, a layer 3 of insulation paste shown in FIG.
An insulating paste coating layer 3' having the same pattern as the insulating paste coating layer 3 and a via hole 7 are formed using the insulating paste.

5- Next, as shown in the jtEs diagram, the third insulating paste coating NI3' is fired together with the substrate l at 850°C to form the third insulating layer 9. At this time, the second insulating layer 6 has a melting point of 850
℃, the pores 5. of the coil and the third insulating layer 4.9 melt during firing. Since it is absorbed by penetrating into lO, most of the second insulating layer 6 on the first conductor pattern 2 in the via hole 7 disappears, and the surface of the fourth body is exposed.

Next, as shown in Figure IIL6, the thick film conductor forming paste (t-J=N) was screen printed, dried, and fired to form a finished product.
A four-body pattern 11 is formed.

A multilayer circuit board can be obtained by repeating the above steps a necessary number of times. As shown in this example, by using two types of insulating pastes with different softening points and melting points, the pie 7 hole can be A multilayer circuit board can be obtained which can be printed on the pattern 9 without clogging, and which also eliminates pores and prevents insulation deterioration due to absorption of moisture and the like.

As explained above, the present invention uses two types of insulating pastes at different firing temperatures to form a dense insulating layer, thereby ensuring connection between upper and lower layer conductors through fine via holes. Moreover, it has the effect of obtaining a multilayer circuit board with excellent insulation properties.

[Brief explanation of the drawing]

l Conductor pattern, 3...strand 1 Insulating paste coating layer, 3
'...II3 insulating paste coating layer, 4...11 insulating layer, 5...pores, 6...2 insulating layers, 7...7 pie holes, 8...2 insulating layers , 9... Genus 3 insulating layer,
10...stomata, 11...fill! 2 conductor pattern. 11 1st bad 2nd bad Hayabusa 3 bad 4th figure 5Δ shi □□

Claims (1)

[Claims] Forming a single conductor pattern on a ceramic substrate III
The 'sl' is applied to the ceramic substrate containing the Ill conductor pattern using an all insulating paste comprising a glass powder with a high melting point and an inorganic oxide powder, and a screen having a pattern for forming earholes. 11. Forming an insulating paste coating layer and firing at a temperature between the softening point and melting point of the high melting point glass powder to form a 1g1 insulating layer.
After 2 steps, an lI2 insulating paste containing a low melting point glass powder is applied to cover the exposed-aligned insulating layer of the Ill conductive pattern, and is fired at a temperature slightly higher than the softening point of the low melting point glass to form an lI2I2. forming an insulating layer, and forming a third paste having a pattern matching the pattern of the first insulating layer on the second insulating layer of the front kite using the first insulating paste and nine screens used in the first insulating layer; A multilayer circuit board characterized by comprising the steps of: forming a coating layer, and firing at a temperature between the softening point and melting point of the high melting point glass in the 511 insulation paste to form an insulating layer. Production method.