JP3003241B2 - Composite of green sheet and plastic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite of a green sheet and a plastic film used in a process of a ceramic circuit board used for an electronic device, and more particularly to a composite applied to a ceramic multilayer board. There is something.

[0002]

2. Description of the Related Art In recent years, a ceramic multilayer substrate has attracted attention as a circuit board having a much higher density than a multilayer printed circuit board. Hereinafter, the handling of a green sheet in a conventional method for manufacturing a ceramic multilayer substrate will be particularly described.

The first conventional method is a method in which a green sheet is handled alone. A green sheet is formed on a PET film containing polyester as a main component.
The green sheet from which the ET film was peeled was cut into a predetermined size, and a via hole 3 for establishing electrical connection between the positioning hole 2 and the interlayer was formed as shown in FIG. 6, and the via hole 3 was filled with a conductor. Thereafter, a predetermined wiring pattern is formed with a conductor on the surface of the green sheet 1.

Thereafter, a plurality of green sheets on which the wiring patterns are formed are laminated and then fired. The second handling method is a method of sticking the green sheet 1 to a stainless steel frame 4 as shown in FIG.
Handling is performed using the corner of the frame 4 as a positioning reference.

[0005]

However, in the above-mentioned conventional structure, in the first method, the green sheet is soft and easily broken, so that it is difficult to handle the green sheet in each step. Heat is applied in the step of filling the conductor and in the step of drying the conductor after printing the wiring, so that the green sheet shrinks greatly and the positional accuracy is deteriorated. Further, when manufacturing a multilayer substrate, a plurality of green sheets on which a wiring pattern is formed must be laminated, and thus the dimensional accuracy of the green sheets is particularly important. In the second method, handling is easy due to the presence of the frame, but it is difficult to cleanly peel off the green sheet attached to the frame, and the frame warps when used for a long time. Further, when the number of layers in a multilayer substrate is increased, the thickness of one green sheet is reduced, and the green sheet is easily broken and easily bent even when the green sheet is attached to a frame. Further, when laser light is used in the via hole forming step, there is a problem that chipping 9 occurs around the via hole 3 of the green sheet 1 on the laser irradiation side as shown in FIG. Was. Further, the conventional ceramic composition has a problem that the substrate is deformed when co-firing with the internal conductor, so that a high-density circuit board cannot be obtained. An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a composite of a green sheet and a plastic film for remarkably improving the handling of a green sheet and obtaining a high-quality ceramic circuit board.

[0006]

In order to achieve this object, a composite of a green sheet and a plastic film of the present invention has a glass transition temperature (hereinafter referred to as Tg) of 85 ° C. on one surface of the green sheet. It has a configuration in which the above plastic film is arranged.

[0007]

According to this structure, since a heat-resistant plastic film is disposed on the green sheet, if the composite is handled as it is, the plastic sheet is easily broken and the green sheet is easily stretched, and the frame is protected. No extra jigs are required, the dimensional change is small even in the heat process when drying the conductor, and the roll-to-roll method can be used, thus significantly improving the handling of green sheets in the ceramic circuit board manufacturing process. Thus, a high-quality and inexpensive ceramic multilayer substrate can be provided. In addition, when the via hole is processed by laser light from the plastic film side, even if chipping occurs around the via hole of the plastic film, the plastic film is discarded in a later process,
There are no inconveniences with the green sheet. Therefore, according to this configuration, the laser can be used for via hole processing, so that productivity can be significantly improved. Furthermore, since the thickness of the green sheet for the multi-layer substrate is thin, the present configuration having the effect of protecting with a plastic film and the effect of improving the lamination accuracy because the dimensional change is small even in the process of applying heat is very effective. Things.

[0008]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. First, the plastic film used in this experiment is introduced.

[0009] (1) Toray Co., Ltd. brand name Torelina,
A film mainly composed of polyphenylene sulfide,
Hereafter referred to as PPS. Its chemical structural formula is shown in (Formula 1).

[0010]

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(2) Trade name of PERIO U of Mitsubishi Plastics Corporation
In T, a film mainly composed of polyetherimide, hereinafter referred to as PEI. Its chemical structural formula is shown in (Formula 2).

[0012]

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(3) Trade name TA manufactured by Mitsui Toatsu Chemicals, Inc.
LPA-1000, a film mainly composed of polyethersulfone, hereinafter referred to as PES. Its chemical structural formula is shown in (Formula 3).

[0014]

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(4) Trade name TA manufactured by Mitsui Toatsu Chemicals, Inc.
LPA-2000, a film mainly composed of polyetheretherketone, hereinafter referred to as PEEK. Its chemical structural formula is shown in (Formula 4).

[0016]

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(5) Kapton, a trade name of Toray Dupont Co., Ltd., a film containing polyimide as a main component, hereinafter referred to as PI. Its chemical structural formula is shown in (Chem. 5).

[0018]

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(6) Toray's trade name Lumirror,
A film mainly composed of polyester, hereinafter referred to as PET. Its chemical structural formula is shown in (Chem. 6).

[0020]

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(7) The above PET film is subjected to a heat treatment at 100 ° C. or more to reduce the shrinkage.
It is called ET. Its chemical structural formula is the same as in (Chemical formula 6).

The properties of these seven types of plastic films are shown in Table 1. In the characteristics of (Table 1), the breaking strength and elongation were measured in accordance with JIS-C2318, and the heat shrinkage was 0.15 mmφ holes at 100 mm intervals. Right angle direction (T
Regarding D), the value of the largest shrinkage ratio was shown when n = 4 after the heat treatment.

[0023]

[Table 1]

As shown in FIG.
A green sheet is formed on a 5 μm plastic film 5 so that the thickness after drying becomes 200 μm, and a green sheet 1 necessary for manufacturing a ceramic circuit board is formed.
And a plastic film 5 composite. Next, the green sheet is NC-bonded through a plastic film.
A 0.15 mmφ via hole was formed by punching. At this time, PET was easily burred, but the other films were excellent in processability. The reason for this is related to the elongation percentage in Table 1, and it is easily presumed that the larger the elongation percentage of the film at the time of breaking, the easier it is for burrs to occur, which is consistent with the results of actual experiments. Further, it is expected that the smaller the value of the breaking strength in Table 1 is, the more excellent the workability is and the longer the life of the pin at the time of mass production is. As for PEEK, the elongation is large but the value of the breaking strength is small.
It was at a sufficiently practical level. In general, engineering plastics having high heat resistance have a small value of elongation and a small value of breaking strength, and thus have excellent punching workability. Next, as shown in FIG.
Is filled with via conductors 7a and dried at 90 ° C. for 10 minutes.
A wiring pattern 7b was formed with a conductor on one surface of the green sheet, and further dried at 90 ° C. for 10 minutes. Then, the green sheet 1 was peeled off from the plastic film 5, and a plurality of green sheets on which the wiring patterns were formed were laminated and fired to obtain a multilayer substrate. Here, when the reliability of the via connection was confirmed, there was a conduction failure only in the case of using the PET film, and as a result of SEM observation of the cross section of the multilayer substrate to find out the cause, it was found that the via was misaligned. Was. This is considered to be due to a large shrinkage of the PET film in the drying step after via filling and wiring printing. Generally, the outer diameter of a multilayer board is 100 mm square, and it is expected that the via diameter will be 0.1 mmφ in the future, so that the deviation when laminating via holes will be less than 50 microns. It is necessary from the point of view. That is, since heat of about 90 ° C. is applied during drying of the conductor, the value of the heat shrinkage at 100 ° C. or less in Table 1 is required to be 0.05% or less for safety. 0.05% of 100mm is 50
Micron. In this experiment, as compared with the conventional handling method described in the section of the conventional example, since the plastic film was disposed, it was possible to easily handle the green sheet which was easily stretched and easily broken. In addition, when the conductor is dried, the green sheet alone shrinks by 1% or more, whereas the green sheet and plastic film composite has a small dimensional change like the thermal shrinkage shown in (Table 1). A ceramic circuit board having good stability, excellent via connection reliability, and high density was obtained. Further, since Tg is a physical property value indicating the degree of heat resistance,
The higher the Tg, the smaller the value of the heat shrinkage except for some errors, and it is clear from Table 1 that a film having a heat resistance of 85 ° C. is more effective, and the experimental results are consistent. ing. In the via filling process, a metal mask with a hole slightly larger than the via hole is placed at the position corresponding to the via hole, and the conductive paste is filled from the metal mask side by printing. However, after removing the metal mask, a land corresponding to the hole of the metal mask was inevitably formed around the via hole. However, as shown in FIG. 3, when the via hole 6 is filled with the via conductor 7a, the filling is performed from the plastic film 5 side, so that the plastic film 5 can be filled with the green sheet 1 even if the via land 12 is generated.
Since the via lands 12 are removed when peeled off from the substrate, the landless vias 11 shown in FIG. 3 can be obtained as a result, and a high-density multilayer substrate can be obtained.

(Example 2) In the step of forming a via hole in Example 1, an experiment was performed using laser light. As shown in FIG. 4, a laser beam 8 was irradiated from the plastic film 5 side of the composite of the green sheet 1 and the plastic film 5. On the laser irradiation side of the plastic film 5,
Chipping 9 occurred, but only at the surface of the plastic film 5, there was no damage to the green sheet 1, and a straight hole of 0.1 mm to 0.2 mm could be drilled. With respect to the seven types of films described in Example 1, there was almost no difference between the films in terms of laser drilling workability. Further, a multilayer substrate was formed in the same manner as in the first embodiment.
In the same manner as in the above, there was no defect due to the use of laser light. This experiment showed that laser light can be used, so that the productivity of drilling could be improved, and the problem of the life of NC punches and mold pins was eliminated, so that mass productivity could be significantly improved. .

(Embodiment 3) First, as in Embodiment 1,
The green sheet was formed on a plastic film having a thickness of 75 μm so that the green sheet had a thickness of 200 μm, and was wound into a roll. Next, as shown in FIG. 5, the green sheet 1 with the plastic film 5 attached thereto is sequentially moved in the longitudinal direction, and in the moving step, the green sheet 1 is put together with the plastic film 5 using the processing machine 10. A via hole was formed and wound up sequentially. Similarly,
After via filling and wiring formation, the green sheet on which the wiring pattern was formed was cut into a predetermined size together with the plastic film, the green sheet was peeled off from the plastic film, and a plurality of the green sheets were laminated. Thereafter, firing was performed to obtain a multilayer substrate. In this experiment, the green sheet was wound in each process, but it is needless to say that the process can be continued by examining the tact of each process. By adopting this method, the problem of handling of green sheets that are easily stretched and torn was solved. In addition, since continuous production called roll-to-roll is possible, and a plastic film with excellent heat resistance is adopted, the lamination accuracy of the multilayer substrate can be improved, and a multilayer substrate with excellent via connection reliability can be produced. became. That is, mass production is possible, and the yield is improved, so that inexpensive multilayer substrates can be mass-produced, and the possibility of introduction to consumer equipment can be obtained. As described above, Examples 1, 2, and
3 describes the case of a multilayer substrate, but it goes without saying that the present invention is also effective in the case of a circuit substrate in which only one sheet is fired without laminating green sheets.

Example 4 In order to obtain a high-density multilayer substrate, a ceramic material having good matching with the internal conductor was examined. First, as a required item for the substrate material, it must be able to be fired at 900 ° C. so that it can be fired simultaneously with a conductor material having a low electric resistance, such as Ag or Cu, and a resistor or a capacitor material. Second, the dielectric constant is lower than the alumina substrate used in the conventional HIC, that is, the dielectric constant is 9 or less. Third, when co-firing with Ag and Cu internal conductors, the interlayer insulation is excellent, and there is no difference in shrinkage between the portion with and without the internal conductor. The reliability between the layers was determined by providing a 2 × 2 mm counter electrode between insulating layers of 200 μm, applying a voltage of 100 V in an environment of 85 ° C. and 85% RH in a constant temperature and humidity chamber, and standing for 1000 hours. The sample was returned to the room, and the insulation resistance was measured and held as 10 ¹⁰ Ω or more. Regarding the deformation of the substrate, the substrate deformation ratio ΔL is defined as (Equation 1) in order to quantitatively express the deformation.

[0028]

(Equation 1)

Here, Lc is the contraction rate of the substrate where the internal conductor is provided, and Ld is the contraction rate of the portion where the internal conductor is not provided.
If ΔL obtained as described above is less than 0.5%, it is evaluated as ○.
Was given a rating. Table 2 shows the composition of the substrate material that almost satisfies the above conditions.

[0030]

[Table 2]

The compositions of glass A and glass B in the table are shown in (Table 3).

[0032]

[Table 3]

First, with respect to the mother glass, a raw material batch prepared so as to have the glass compositions of A and B shown in (Table 3) was put in a platinum crucible, melted at 1500 to 1600 ° C. for 2 to 3 hours, and then quenched in water. Thereafter, the powder was pulverized by a ball mill until the average particle diameter became about 1.8 μm to obtain a mother glass powder. Nos. 1 to 5 in (Table 2) were obtained by changing the mixing ratio of glass A powder and alumina powder to 60/40 to 40/60 by weight, and Nos. 6 to 10 were glass B powders. No. 11 to 13 were prepared by changing the mixing ratio of 55/45 to 35/65 in weight ratio between the glass B powder and the cordierite powder in a weight ratio of 60/40 to 45/45.
The mixing ratio was changed to / 55. Green sheets were formed from these ceramic powders using an acrylic binder, and the above experiment was performed. The results are shown in (Table 4).

[0034]

[Table 4]

For sample No. 10, the reliability between the layers was N
G was 65 parts by weight of alumina powder as a filler component per 35 parts by weight of glass powder, and it is considered that sintering was not sufficient because the amount of filler component was too large. That the composition range of each component of No.1~13 except sample No.10, Al ₂ O ₃ 13.97~60 wt%, SiO ₂ 22.8~56.52 wt%, B ₂ O ₃
2.32 to 5.1 wt%, Na ₂ O 0.6~2.1 wt%, K ₂ O 0.6~1.56 wt%, CaO2.4
~ 4.8 wt%, MgO 0.84 ~ 8.53 wt%,
If the composition is selected so that the total amount becomes 100% by weight in the composition range of 7.2 to 12% by weight of PbO, the composition is excellent in reliability and has good matching with the internal conductor as compared with the conventional multilayer substrate. It was found that a high-density multilayer substrate could be obtained.

[0036]

As described above, the present invention is characterized in that a plastic film having a Tg of 85 ° C. or more is disposed on one surface of a green sheet. The ceramic circuit board protects the green sheet, which is easy to tear and stretches, eliminates the need for an extra jig such as a frame, has a small dimensional change even in the heating process when drying the conductor, and can adopt a roll-to-roll method. The handling of the green sheet in the manufacturing process of (1) is remarkably improved, and a high-quality and inexpensive ceramic multilayer substrate can be provided.
Also, when the via hole is processed with laser light, even if chipping occurs around the via hole of the plastic film by irradiating from the plastic film side, the plastic film is discarded in the subsequent process, so there is no inconvenience for the green sheet. There is no. Therefore, according to this configuration, a laser can be used for the via hole, so that the productivity can be significantly improved. Furthermore, since the green sheet for a multilayer substrate is thin, the effect of protecting with a plastic film and the effect of improving the lamination accuracy and improving the reliability of via connection can be improved because the dimensional change is small even in the process of applying heat. Is very effective.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a composite of a green sheet and a plastic film according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the composite in one step of the ceramic circuit board using the embodiment.

FIG. 3 is a sectional view of a composite in another manufacturing process of the ceramic circuit board using the embodiment.

FIG. 4 is a cross-sectional view of a composite showing still another manufacturing process of the ceramic circuit board using the embodiment.

FIG. 5 is a sectional view of a composite showing still another manufacturing process of the ceramic circuit board using the same embodiment.

FIG. 6 is a perspective view of a green sheet in one manufacturing process of a conventional ceramic circuit board.

FIG. 7 is a cross-sectional view of a green sheet in another manufacturing process of a conventional ceramic circuit board.

FIG. 8 is a cross-sectional view of a green sheet in another manufacturing process of a conventional ceramic circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Green sheet 2 Positioning hole 3 Via hole 4 Frame 5 Plastic film 6 Via hole 7a Via conductor 7b Conductor pattern 8 Laser beam 9 Chipping 10 Processing machine 11 Landless via 12 Via land

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-231789 (JP, A) JP-B-56-32800 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 18/00 B32B 27/06 H05K 1/03 610 H05K 3/46

Claims (5)

(57) [Claims] 1. A composite of a green sheet and a plastic film in which a plastic film having a glass transition temperature of 85 ° C. or more is disposed on one surface of the green sheet, wherein the plastic film is made of polyphenylene sulfide or polyether. A film mainly composed of imide, polyethersulfone, polyetheretherketone, or polyimide ;
The green film is green prior to firing the green sheet.
A composite of a green sheet and a plastic film, which is peeled off from the sheet. 2. A composite of a green sheet and a plastic film in which a plastic film having a glass transition temperature of 85 ° C. or more is disposed on one surface of the green sheet, wherein the ceramic component of the green sheet is Al.
₂ O ₃ 13.97 to 60% by weight, SiO ₂ 22.8% to
56.52 wt%, B ₂ O ₃ from 2.32 to 5.1 wt%,
Na ₂ O from .6 to 2.1 wt%, K ₂ O 0.6~1.
56% by weight, 2.4 to 4.8% by weight of CaO, MgO
0.84 to 8.53 wt%, a selected composition such that 100% by weight total composition range of PbO 7.2 to 12 wt%, the plastic film, green sheet
What is peeled off from the green sheet prior to firing of the sheet
Composite green sheet and the plastic film, characterized in that it. 3. The step of drilling a via hole is performed by a green process.
A plastic film is placed on one side of the sheet
With the plastic film side
The green sheet according to claim 1 or 2,
Composite of plastic film. 4. A via hole is filled with a via conductor, and the filled via is filled.
A) The process of drying the conductor is performed on one side of the green sheet.
Is performed with the plastic film placed
The green sheet and the press according to claim 3, wherein
Composite of plastic film. 5. A plastic film is not disposed.
On the other side, form a wiring pattern with a conductor,
Drying the wiring pattern, the plastic
It is performed in a state where the film is arranged.
The green sheet and plastic according to claim 1.
Stick film composite.