JPS603193A - Method of producing ceramic 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 [Technical Field of the Invention] The present invention relates to a method for manufacturing a ceramic multilayer wiring board.

[Technical background of the invention and its problems]

Conventional ceramic multilayer wiring boards were generally manufactured as follows.

That is, a certain amount of inorganic raw materials are weighed out, mixed and pulverized to obtain the required average particle size, and after drying, a solvent, a binder, a plasticizer, a dispersant, etc. are added, and if necessary, further , an inorganic black agent, etc. are also added and mixed thoroughly. After that, the de-wrapping machine (two people, further stirring, defoaming,
Adjust the slurry to the required viscosity.

When the required viscosity (-) is reached, a doctor knife with a certain gap of the doctor blade device is used to supply the slurry, and the slurry flowing out from the doctor knife part is placed on the carrier film (with a certain thickness).The carrier film advances. Inside (= passing through the drying section, at that time) a certain amount of the solvent, etc. of the Nisslary is scattered, and a green sheet (called an unsintered sheet or green sheet), which looks like chewing gum, can be obtained. .

A conductive circuit layer is formed on the green sheet by printing a conductive paste containing molybdenum (MO) or tungsten (W) as a main component using a screen printer or the like.

Next, an insulating paste layer is printed on the conductor layer (2) except for through holes connecting the upper and lower conductors and other necessary places. Condition (- Multilayer printing is performed sequentially to form a printed multilayer wiring board.

This nuclear printing, green sheet is 1400-1600°
It is fired in a weakly reducing atmosphere of C, and then, if necessary C2, after plating, attaching a lead frame, etc., IC, R, C, etc. are mounted at specific locations on the top layer printed pattern.
Wires are attached to form a ceramic multilayer wiring board.

A particular problem with this manufacturing method was that when a multi-layer printed green sheet was fired, the fired substrate warped so much that it was impossible to attach a lead frame afterwards, and even more Chip mounting and wire bonding for C and R were impossible.

One effective method to solve this problem is, for example, as disclosed in Publication No. 57-27060. However, when inorganic raw materials with four particle sizes were used, there was still a problem in that the fired substrate had a large degree of warpage.

[Purpose of the invention]

As described above, the present invention provides a method for improving the problem of the conventional method in which large warpage occurs even when a multilayer wiring board is formed using an insulating paste of the same quality as the board.

[Summary of the invention]

In the method of the present invention, after weighing the inorganic raw materials, they are mixed and pulverized until the average particle size required for the substrate is obtained, and then a part of them can be used as is, or if necessary, a black agent can be added to the mixture. The inorganic raw material for the insulating paste is obtained by pulverizing it to an average particle size smaller than that of the inorganic raw material for the substrate. Using this, thoroughly mix and stir with ethyl cellulose, terpineol, etc. Make insulation paste.

By using the insulating paste made in this way (2), a ceramic multilayer wiring board with a small warpage of about 70 μm/1 inch can be obtained after firing.

〔Effect of the invention〕

By using the method of the present invention, the following effects can be obtained.

b) The fired substrate has less warpage, which is a major contribution to industry.

(Example) Re-firing for warping is no longer necessary, and increase in conductor resistance can be prevented.

-) Similarly, re-firing for warping is no longer necessary, making plating or lead frame attachment in the post-process easier.

[Embodiments of the invention]

Aluminum oxide (A40g) 92% N (the same applies below), 5% silicic anhydride (Si02), 1.5% each of magnesium oxide (MgO) and calcium oxide (Cab)
If these are 100 parts, then 4 parts by weight of chromic oxide (CrzOs) and 1 part by weight of titanium oxide (TiO) are weighed (2 parts by weight), and these are combined in a vibration mill,
The mixture was mixed and ground until the average particle size was 1.8 μm.

Some of them have a double average particle size of 1.5 μm (-
I smashed it until it was.

Separate these inorganic powders (after drying, 1.8 μm
The large particle size powder was used for substrates, and the following additives (two-solvent binder, plasticizer, etc.) were added.

Alumina powder 100 parts Trichlorethylene 201 n-butanol 10 parts Tet2-chloroethylene 81 Polyvinyl butyral 5# TBP 2 N After thoroughly mixing these, defoaming and viscosity 30.00
The slip (slurry) made to 0 centipoise (CP) was supplied to a doctor blade device (=== to obtain a green sheet. This green sheet was cut into 50 x 60 pieces, and the green sheet (-, screen, A printed circuit layer was formed using molybdenum (Mo) paste using a printing machine.After drying, powder for insulation paste, ethyl cellulose, and pulverized powder for insulating paste were ground to an average particle size of 1.5 μm.
An insulating paste made of terpineol was printed except for through holes or other specific areas.

Similarly, after this insulating layer was dried, a conductive layer was placed on top of the insulating layer, followed by an insulating layer, and so on to form a multilayer wiring. This layered structure is shown in cross section in FIG.

Next, this substrate was fired at 1500° C. in a weakly reducing atmosphere of a mixed gas of hydrogen gas (N2), window gas (N2), and wet N2.

Simultaneously: At this time, we used the same inorganic raw material as the substrate and the same average particle size, that is, 1.8 μm, and made a separate substrate with the same multilayer structure as above using an insulating paste made using this material. was also fired under the same conditions.

This 1.8 μm insulating paste had thick warpage, so it was fixed and re-fired at a low temperature of just under 1400°C.

As a result, as shown in FIG.
There was also 11,150 ml. On the other hand, when the insulation paste with a small particle size of 1.5 μm was used for the substrate, the average thickness of the 10 sheets was similarly 0.17 m150 m.

The sled was measured using a 3E-3C universal surface profile measuring device manufactured by Koita Giken Co., Ltd.

Here, warping of the substrate after firing is common (20, 2 to 0
．． Since 14 mg15Q AlB is required,
Considering this point, ``■'' with a smaller average particle size is more likely to satisfy this standard, but ``■'' with the same particle size results in warpage that is larger than the standard and requires correction.

Therefore, as mentioned above, we refired at 1400"C to correct the warpage. Figure 3 shows the measurement results of the conductor resistance on the top layer conductor pattern before and after refiring. , 0 is the value before warping, that is, after only one firing, and this is the average value measured for each of five samples.

As can be seen from this result, by passing through the firing furnace 21 times, the Mo
The conductor is oxidized and the conductor resistance increases.

Therefore, if a multilayer wiring board is manufactured using an insulating paste made from a homogeneous inorganic material with a particle size smaller than that of the board, it can be fired with a sufficiently small warp without the need for warping, and it is possible to prevent conductor resistance build-up.

Here, the general standard for conductor resistance is 20 mQ/mouth.

(Secondly, it eliminates the need for re-firing to correct warpage and prevents oxidation and scattering of the conductor pattern, making it easier for plating to adhere in the subsequent plating process. The brazing process is also much easier.

When the conductor pattern becomes thinner, the base material on which the plating material is plated is inevitably thinner (2), so the adhesion of the plating becomes poorer, and the thinner leads to a decrease in the adhesion between the molybdenum and the lead frame. The method of the present invention, which requires only one firing, can be said to make a great contribution.

In the above embodiments, an alumina multilayer substrate was described, but it can be easily analogized to a substrate using other general ceramic materials.

Furthermore, the same effect can be obtained by using a conductive paste other than the conductive paste mainly composed of Mo, for example, a conductive paste mainly composed of W.

Furthermore, the black agent may be added from the beginning and pulverized as in this example, or it may be mixed with ethyl cellulose, terpineol, etc. when preparing an insulating paste. In short, it is sufficient that the insulating paste has a smaller average particle size as an inorganic raw material than that of the substrate and is a homogeneous inorganic raw material.

The conductive pattern or the insulating paste can be printed by an inkjet method using ultrasonic waves, for example, without using a screen printer.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing an example of the layer structure of a ceramic multilayer wiring board, Figure 2 is a characteristic diagram showing the glue after firing the ceramic multilayer structure board, and Figure 3 is the conductor resistance when using the conventional method. Characteristic diagram showing changes in . Agent: Patent Attorney Noriyuki Chika (and 1 other person) No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A step of weighing inorganic raw materials, a step of mixing, pulverizing, and drying the inorganic raw materials, a step of adding a solvent, a binder, a plasticizer, and a dispersant, mixing, stirring, and defoaming; A step of creating a green sheet using a grade forming device (2); a step of forming a conductor circuit using a molybdenum (Mo) or tungsten (W) based conductive paste using a screen printing machine; In order to connect the upper and lower conductors with through holes, there are two steps: a step of printing insulating paste on a specific location excluding that part, and a step of repeating the printing of this conductor and insulating paste alternately to form a multilayer structure C2. In the method for manufacturing a ceramic multilayer wiring board, which includes the step of firing this in a weakly reducing atmosphere, an inorganic raw material of the same quality as the board is used as the insulating paste,
A method for manufacturing a ceramic multilayer wiring board, characterized in that the average particle size is smaller than the average particle size of the inorganic raw material for the substrate.