JPH0391295A - Multilayer electronic printed circuit board - Google Patents

Abstract

PURPOSE:To enhance high-moisture resistance and high-temperature resistance and improve reliability by using an electronic circuit where a direct film-shaped element is formed on the surface of a sintered porous ceramic body, laminating it, and then impregnating a resin into a pore within a sintered body. CONSTITUTION:Electronic printed circuit boards 1, 1 are laminated above the under a center electronic printed circuit board 2 and these are adhered into one piece. A film-shaped conductive circuit 12 and a film-shaped conductive circuit 13 are adhered and formed onto the surface side of a sintered porous ceramic 11 body 11 as a substrate and the film-shaped conductive circuit 12 is adhered and formed onto the rear side of this electronic circuit board 1. Also, in this adhesion state, the film-shaped conductive circuit 12 and the lower surface of the film-shaped resistor 13 are engaged on a recessed and projected part of the surface among a large number of ceramic particles 10 consisting the sintered porous ceramic body 11 in wedge shape. Also, a resin 14 which is impregnated after lamination is filled into a pore which is formed among the ceramic particles 10 in the sintered porous ceramic body 11. The porous ceramic and film-shaped elements are directly adhered in this manner, thus enabling the film-shaped elements to be extremely stable against environmental change such as temperature and humidity.

Description

[Detailed description of the invention] [Industrial application field] In the present invention, a film element such as a conductive circuit is formed on one surface.

This invention relates to a highly reliable multilayer electronic circuit board.

[Prior art]

In recent years, various types of electronic circuit boards have become known and put into practical use.1 For example, electronic circuit boards using glass-epoxy composites, alumina sintered bodies, mullite sintered bodies, etc. as substrate materials have been proposed. has been used. and,
As one method for promoting higher integration, a mounting method in which silicon integrated circuits and the like are directly mounted on a substrate is being considered.

However, since the glass-epoxy composite has a significantly different coefficient of thermal expansion from that of silicon integrated circuits, the silicon integrated circuits that can be directly mounted on the substrate are limited to extremely small ones. In addition, since the dimensions of a substrate made only of a glass-epoxy composite tend to change during the five-circuit forming process, it is difficult to apply this method to substrates that require particularly fine and precise circuits.

In addition, aluminum sintered bodies and mullite sintered bodies have high hardness and poor machinability. For this reason, if machining is required, for example to create through holes, etc., a method is used in which the machining is performed at the stage of forming the green body and then fired. However, it is difficult to cause uniform shrinkage during firing,
It has been difficult to manufacture products that require particularly high dimensional accuracy or have large dimensions.

Therefore, in order to deal with these problems,
No. 87190 or JP-A-61-82689,
A substrate in which the pores of porous ceramic are impregnated with resin has been proposed.

This substrate is made by varying the porosity of the ceramic to match the thermal expansion of the component 1 to be mounted, such as a silicon integrated circuit, and has low expansion and excellent dimensional stability.

In addition, machining is easy and it can be made larger and lighter.

On the other hand, in recent years, electronic circuit boards have become more multilayered in order to achieve higher integration. Moreover, instead of chip components such as chip resistors and capacitors, electronic circuit boards having film-like elements in which these elements are formed on circuits in the form of films have been developed.

In this way, by forming film-like conductive circuits, resistors, capacitors, and other film-like elements, the electronic circuit board can be made smaller and lighter.

[Problem to be solved]

However, the electronic circuit board in which film-like elements are formed on the porous ceramic resin-impregnated substrate described above has poor reliability in use.

That is, in a porous ceramic-resin-impregnated body, since the membrane elements formed on the surface thereof are formed on the resin, the membrane elements are significantly influenced by the behavior of the resin. For example, there is a major drawback in that initial characteristics 1, such as resistance value and capacitor capacity, of the membrane element in contact with the resin vary greatly due to high humidity and high temperature.

In view of these conventional problems, the present invention takes advantage of the advantages of the porous ceramic sintered body-resin impregnated substrate described above. Excellent high temperature resistance. The present invention aims to provide a highly reliable multilayer electronic circuit board.

[Means for Solving the Problems] The present invention produces an electronic circuit board by directly forming film-like conductive circuits, resistors, capacitors, and other film-like elements on the surface of a porous ceramic sintered body, and then This multilayer electronic circuit board is characterized in that circuit boards are laminated and then resin is filled into the pores of the porous ceramic sintered body.

The most noteworthy feature of the present invention is that an electronic circuit board in which membrane elements are directly formed on the surface of a porous ceramic sintered body is used, and these are laminated, and then resin is impregnated into the pores of the sintered body. That's true.

That is, in the electronic circuit board of the second aspect of the present invention, a membrane element such as a conductive circuit is inserted into the pores and irregularities of the surface of the porous ceramic sintered body in a wedge shape and directly adheres thereto. On the other hand, the pores other than the part where the membrane element is formed are filled with resin after the electronic circuit boards are laminated.

To form a film-like element such as a conductive circuit on the surface of a porous ceramic sintered body, first, a paste containing particles to form a film-like element is applied to a ceramic formed body by a method such as printing. There is a method of coating and then firing the ceramic green body at a temperature at which a sintered body is formed.

Another method is to first prepare a porous ceramic sintered body, then apply the paste on its surface and then bake it.

Furthermore, there is a method in which a film element such as a conductive circuit is formed by vapor deposition, sputtering, etc. by masking the surface of the porous ceramic sintered body except for the part that will become the circuit, and then removing the mask.

In either method, it is important that the porous ceramic sintered body and the membrane element are in direct contact with each other.

As described above, the direct contact between the porous ceramic and the membrane element makes the membrane element extremely stable against environmental changes such as temperature and humidity.

The term "membrane element" here refers to a conductive circuit as described above.

Refers to electronic components formed in the form of a film on a substrate, such as film resistors and film capacitors. Further, these film elements are formed on one or both sides of the electronic circuit board.

The porous ceramic sintered body may be made of cordierite, aluminum, or aluminum nitride. There are ceramics whose main component is at least one of mullite, magnesium titanate, argonium titanate, silicon dioxide, lead oxide, zinc oxide, beryllium oxide, tin oxide, barium oxide, magnesium oxide, and calcium oxide. . Among these, cordierite is a preferred material because its coefficient of thermal expansion is close to that of silicon integrated circuits.

In the present invention, the porous ceramic sintered body has an average pore diameter of 0. It is preferable that it is 2-15 micrometers. The reason for this is that when the average pore diameter is smaller than 0.2, the adhesion between the membrane element and the porous ceramic sintered body decreases. That is, this is because the wedge effect for improving adhesion is reduced.

On the other hand, if the average pore diameter is larger than 15 μm, the membrane element will penetrate considerably deeper than the surface of the porous ceramic sintered body, making it difficult to form a highly accurate electronic circuit board.

Further, in the present invention, the porosity is preferably 10% (volume ratio) or more. The reason for this is.

This is because if the porosity is less than 10%, the wedge effect will be reduced.

Furthermore, the conductivity between the front and back sides of the board created in this way is as follows.

After filling the porous ceramic sintered body with resin, through holes are formed, and electrical conductivity can be easily established by electroless copper plating or the like.

Therefore, the electronic circuit board configured as described above is made into a multilayer body by bonding a plurality of the electronic circuit boards in a laminated manner.

Thereafter, the pores of the porous ceramic sintered body are impregnated with resin to form a multilayer electronic circuit board (see FIG. 1).

Examples of the resin to be impregnated into the sintered body include epoxy resin, polyimide resin, triazine resin, polyparabanic acid resin, polyamitimide resin, silicone resin, epoxy silicone resin, acrylic acid resin, methacrylic acid resin, anilic acid resin, phenol resin, There are urethane resins, furan resins, fluororesins, etc.

Further, as a method of impregnating these resins into a porous sintered body, there is a method of heating and melting the resin and immersing a laminate of electronic circuit boards in the resin.

Other methods include a method of dissolving a resin in a solvent and impregnating it, and a method of impregnating a resin in a monomer state and then turning it into a polymer.

Further, in the above lamination, it is preferable to interpose the following insulating layer between each electronic circuit board.

By interposing the insulating layer in this manner, contact between the conductors on the upper and lower substrates is prevented.

As the insulating layer, a resin or a composite material of a resin and an inorganic material is used. As the resin, epoxy resin, phenol resin, polyimide resin, etc. are used. As a composite material of resin and inorganic material, epoxy resin and glass fiber, phenol resin and silica powder, epoxy resin and mica, etc. are used.

Furthermore, the above-described insulating layer may be further provided on the surface of the multilayer electronic circuit board obtained as described above, and a conductive layer may be formed thereon (see FIG. 4).

The above-mentioned conductor layer refers to an electronic circuit. Formation of the conductor layer is 1
For example, when laminating metal foil, it is vapor-deposited.

This is carried out by methods such as sputtering, electrolytic or electroless plating.

[Action and effect]

In the multilayer electronic circuit board of the present invention, since each electronic circuit board has a membrane element in direct contact with the surface of the porous ceramic sintered body, the membrane element is wedged between the particles of the sintered body. It is strongly connected to the shape.

The membrane element does not peel off. Furthermore, since the pores of the portion where the membrane element is not formed are filled with resin, it has excellent high humidity resistance and high temperature resistance.

In addition, filling the board with resin increases the strength of the entire board, making it less likely to crack, and at the same time making machining easier and preventing processing defects such as chips and chipping. Also,
It is effective in preventing gas permeation and reducing the influence from the usage environment.

Therefore, according to the present invention, high temperature resistance, high temperature resistance, and machinability are excellent. A highly reliable multilayer electronic circuit board can be provided.

〔Example〕

First Embodiment Regarding the multilayer electronic circuit board according to the embodiment of the present invention, the first embodiment
This will be explained using FIGS.

The multilayer electronic circuit board is as shown in FIG.

Electronic circuit boards 11 are stacked above and below a central electronic circuit board 2, and these are bonded together. The electronic circuit board 1 is as shown in FIG.

On the front side of the porous ceramic sintered body 11 as a substrate,
A film-like conductive circuit 12 and a film-like resistor 13 are formed in close contact with each other on the back side.

Further, the above-mentioned close contact state is as shown in FIG.

A film-like conductive circuit 12 is formed on the uneven surface portion between the large number of ceramic particles 10 constituting the porous ceramic sintered body 11.
．． The lower surface of the film resistor 13 is wedge-shaped. Furthermore, inside the porous ceramic sintered body 11, in the pores formed between the ceramic particles 10,
After lamination, the impregnated resin 14 is filled.

Also, in the electronic circuit board 2, the electronic circuit board 1
It is similar to

As described above, the multilayer electronic circuit board of this example is one in which five electronic circuit boards 2 are provided between the electronic circuit boards 1.1, and each electronic circuit board 1, 1.2 has film-like elements on both the front and back sides. has. Therefore, the two examples are multilayer electronic circuit boards with six layer circuits.

Moreover, since the multilayer electronic circuit board is made into a laminate, the entire board is immersed in molten resin to be impregnated with the resin, so that the resin 14 is also filled between each board, and the surface thereof is It is in a state covered with the resin.

Second Embodiment As shown in FIG. 4, this embodiment is a multilayer electronic circuit board with an eight-layer circuit, in which a conductive layer is formed on the insulating layer on the outermost surface as well.

That is, one example of a multilayer electronic circuit board includes an electronic circuit board 51,
52 and 53 are laminated and bonded together, and an insulating layer 3 is provided on the upper and lower outermost surfaces, and a conductor layer 40 is provided on the surface thereof.

Each of the above-mentioned electronic circuit boards 51, 52.53 includes film-like conductive circuits 512, 522, 532. Film resistor 513, 52
3,533. is formed on its surface. Further, between the film-like conductive circuits and film-like resistors on the electronic circuit boards 51, 52, and 53, and further between the outermost conductor layer 40, there are board-to-substrate conductive through holes 55.
Through-holes 57 are provided in each substrate. In addition,
An impregnated resin layer 14 is interposed between each of the electronic circuit boards 51, 52, and 53 to ensure electrical insulation between them.

These film-like conductive circuits 12. and a film resistor 13.

The state of close contact with the porous ceramic sintered body as a substrate, the resin filling state within the porous ceramic sintered body, etc. are the same as those of the electronic circuit board l shown in the first embodiment.

Therefore, in the multilayer electronic circuit boards according to the first and second embodiments, each of the electronic circuit boards constituting the multilayer electronic circuit boards has the above-described structure, and resin is contained in the pores of the porous ceramic sintered body. Because it is impregnated, it has excellent high temperature resistance and high temperature resistance 3 machinability.

Highly reliable.

Third embodiment This is shown in the second embodiment. 8 layer circuit multilayer electronics 2 A circuit board (see FIG. 4) was manufactured and tested.

The multilayer electronic circuit board was manufactured by first preparing an electronic circuit board A and an electronic circuit board B, and then laminating the electronic circuit board B between the electronic circuit boards A and A.

That is, in order to produce the electronic circuit board A, the average particle size is 1.
2 parts by weight of polyvinyl alcohol, 1 part by weight of polyethylene glycol, 0.5 parts by weight of stearic acid, and 100 parts by weight of water were mixed with 100 parts by weight of 8 μm cordierite powder, mixed in a ball mill for 3 hours, and then sprayed. Dry.

Collect an appropriate amount of this dried material and use a metal press to perform 1. O
Bottom shape with t/cd pressure, size 220mm x 250
iaX 1. 2m, density 1.5g/cIIl (60v
o 1%) was obtained.

This formed body was fired in the air at 1400° C. for 1 hour to obtain a porous cordierite sintered body.

The obtained porous ceramic sintered body has a thickness of 0°25f.
flI11, density 1.8g/cJ porosity 30vo
l (volume)%, and the average pore diameter was 3.2 μm.

On the surface of this porous cordierite sintered body, an average grain size of 1
Viscosity 90 Pa - containing 46% of 1 μm silver-platinum particles.
The paste of s was printed on a 325 mesh screen. As a result, a conductive circuit as a membrane element was formed on the porous cordierite sintered body, dried, and then baked at 850° C. in air.

At this point, the adhesion strength of the conductive circuit pattern was 3 kg/ml11''.
A 60 Pa-s paste was printed using a 325 mesh screen to form a film resistor as a film element on the conductor. After drying.

Baked in air at 850°C. The resistance value at this time is 23Ω
/It was a mouth.

Here, this substrate was subjected to a high temperature and high temperature life test for 1000 hours at 85° C. and 85% RH (relative humidity). As a result, the rate of change in resistance value was 0.15%, indicating excellent stability.

Through the above steps, electronic circuit board A was manufactured.

Next, in order to produce electronic circuit board B, the average particle size is 2.
For 50 parts by weight of alumina powder of 4 μm, 50 parts by weight of alumina powder with an average particle size of 0.7 μm, 12 parts by weight of polyacrylic ester, 1 part by weight of polyester dispersant, 2 parts by weight of dibutyl phthalate, and 50 parts by weight of ethyl acetate. After mixing in a ball mill for 3 hours, a sheet was formed.

This formed body was fired in air at atmospheric pressure at a temperature of 1550° C. for 1 hour to form a porous sintered body.

The obtained sintered body has a thickness of 0.25 mm and a density of 2 g.
g/cwt, porosity is 25Vo1%, and average pore diameter is 1.
It was 2 μm.

A paste with a viscosity of 110 Pa-s containing 41% of lanthanum polide-tin oxide particles with an average particle size of 18 μm was printed on the surface of this sintered body using a 250 mesh screen.
A film resistor was formed, dried and then baked at 900°C in nitrogen.

Next, a paste with a viscosity of 120 Pa-s containing 50% copper particles with an average particle size of 8 μm was placed on top of this film resistor for 25 minutes.
A conductor circuit was formed by printing with a 0 mesh screen, dried and then baked at 600°C in nitrogen. The adhesion strength of the pattern at this time was 2.5 kg/ttm”
Met. Further, the resistance value at this time was 80Ω/mouth.

Furthermore, when this substrate was subjected to a high temperature and high temperature life test for 1000 hours at 85° C. and 985% RH, the rate of change in resistance value was 0.8%, indicating excellent stability.

Through the above steps, electronic circuit board B was manufactured.

Next, as shown in FIG. Laminated like this.

Next, the laminate is impregnated with a two-component epoxy resin.

After curing, a multilayer electronic circuit board was obtained. This impregnation was performed by deaerating the laminate under vacuum, and then pouring an uncured and highly fluid resin into a container containing the laminate, and impregnating the resin. Further, during this impregnation, a further pressure of 10 atm was applied to ensure sufficient impregnation. Thereafter, the resin was cured by heating at 150° C. for 8 hours.

Next, a through hole was formed in this laminate using a diamond drill having a diameter of 0.40 am, and electroless copper plating of 10 tIm was applied to establish electrical continuity between the three substrates.

Next, on the front and back sides of the laminate, an insulating layer of 0.05
m+++ BT resin prepreg and 1 on top
8 μm copper foil was placed and vacuum pressed to form conductor layers on each of the front and back surfaces.

Next, holes were drilled in the laminate using a diamond drill with a diameter of 0.40 mm to the front and back sides and to the middle layer, and holes of 15 μm were drilled in the same manner.
After applying electroless copper plating to establish continuity, the conductor layers on the front and back surfaces were etched to form a circuit.

The thus obtained multilayer electronic circuit board was an 8-layer circuit, and had a total thickness of 1.05 mm, which was extremely thin.

Moreover, this multilayer electronic circuit board.

It had an extremely high packaging density, with 46 film-like resistors and 24 capacitor elements built-in per lc/lc.

For this multilayer electronic circuit board, 260 seconds at 20°C
A heat resistance test was conducted with repeated oil dips at °C for 30 seconds. As a result, no defects such as wire breakage or separation between substrates occurred even after 500 cycles.

In addition, when this multilayer electronic circuit board was subjected to a high temperature and high temperature life test for 1000 hours at 85°C and 85% RH, the rate of change in resistance value was 0.38% for the ruthenium oxide type.
The lanthanumolide-tin oxide type was extremely stable at 1.53%.

As shown in FIG. 2 and FIG. 3, the electronic circuit boards A and B have a film-like conductive circuit 12 and a film-like resistor 13 firmly attached to both the front and back surfaces of the porous ceramic sintered body 11. (See Example I for details).

On the other hand, for comparison, a porous cordierite sintered body was produced in the same manner, immediately impregnated with the same two-component epoxy resin, and copper foil was laminated at the same time to obtain a substrate. Next, a circuit was formed by etching. The beer strength at this time was 1.8 kg/mark, which was low.

Moreover, in the electronic circuit boards A and B described above.

Each board has a length of 350+n+++ and a width of 250mm,
We were able to drill over 120,000 holes. Like this 2
The electronic circuit board of the present invention has high strength and excellent machinability.

[Brief explanation of drawings]

1 to 3 show the multilayer electronic circuit board of the first embodiment, FIG. 1 is a sectional view thereof, FIG. 2 is a sectional view of one electronic circuit board, and FIG. 3 is an enlarged sectional view of the main parts. . FIG. 4 is a sectional view of the multilayer electronic circuit board of the second embodiment. 1, 2. 51. 52. 53 16. Electronic circuit board 10... Ceramic particles. 9 11゜12゜13゜14゜3゜40゜Porous ceramic sintered body. Membrane conductive circuit membrane resistor element. resin. insulation layer. Conductive layer embedding by applicant

Claims (2)

[Claims] (1) An electronic circuit board is produced by directly forming a film-like conductive circuit, a film-like element such as a resistor, a capacitor, etc. on the surface of a porous ceramic sintered body, and then the electronic circuit board is laminated, and then A multilayer electronic circuit board characterized in that the pores of the porous ceramic sintered body are filled with resin. (2) In the first claim, the multilayer electronic circuit board is a multilayer electronic circuit board laminated with an insulating layer made of resin or a composite material of resin and inorganic material interposed between each electronic circuit board. electronic circuit board.