JPH04286182A - Composite body of green sheet and plastic film - 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]

0001

[Field of Industrial Application] The present invention relates to a composite of a green sheet and a plastic film used in the process of manufacturing ceramic circuit boards used in electronic devices, and is particularly applicable to the production of ceramic multilayer boards. It is something.

0002

2. Description of the Related Art Ceramic multilayer boards have recently attracted attention as circuit boards with much higher density than multilayer printed boards. In the following, the conventional method for manufacturing a ceramic multilayer substrate, particularly the handling of green sheets, will be explained.

[0003] The first conventional method is to handle a green sheet alone, in which a green sheet is formed on a PET film whose main component is polyester.
The green sheet from which the ET film was removed was cut into a predetermined size, and as shown in FIG. 6, a positioning hole 2 and a via hole 3 for making an electrical connection between the layers were formed, and the via hole 3 was filled with a conductor. After that, a predetermined wiring pattern is formed using a conductor on one surface of the green sheet.

[0004] After that, a plurality of green sheets on which the wiring patterns have been formed are laminated and then fired. The second handling method is to attach the green sheet 1 to a stainless steel frame 4 as shown in FIG.
Handling is performed using the corners of the frame 4 as positioning standards.

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional configuration, in the first method, the green sheet is soft and easily torn, making it difficult to handle in each process, and it is difficult to handle the conductor in the via hole. Heat is applied during the process of filling the conductor and drying the conductor after printing the wiring, which causes the green sheet to shrink significantly, resulting in poor positioning accuracy. Further, when manufacturing a multilayer board, it is necessary to laminate a plurality of green sheets each having a wiring pattern formed thereon, so the dimensional accuracy of the green sheets is particularly important. In the second method, handling is easy because of the frame, but it is difficult to cleanly remove the green sheet attached to the frame, and the frame warps after long-term use. Furthermore, as the number of layers increases in a multilayer board, the thickness of one green sheet becomes thinner, and even when the green sheet is attached to a frame, there is a problem that the green sheet is easily torn and easily bent. Furthermore, if a laser beam is used in the process of forming via holes, there is a problem in that chipping 9 occurs around the via holes 3 of the green sheet 1 on the laser irradiation side, as shown in FIG. Ta. Furthermore, with conventional ceramic compositions, the substrate deforms when co-fired with the internal conductor, so there is also the problem that a high-density circuit board cannot be obtained. The present invention solves the above-mentioned conventional problems, and significantly improves the handling of green sheets.
The purpose is to provide a composite of green sheet and plastic film for obtaining high quality ceramic circuit boards.

[0006]

[Means for Solving the Problems] In order to achieve this object, the composite of the green sheet and plastic film of the present invention has a glass transition temperature (hereinafter referred to as Tg) of 85° C. on one side of the green sheet. It has a configuration characterized in that the above plastic films are arranged.

[0007]

[Function] According to this configuration, since a heat-resistant plastic film is arranged on the green sheet, if this composite is handled as it is, the plastic film protects the green sheet, which is easily torn and stretches, and also protects the frame. It eliminates the need for extra jigs such as jigs, minimizes dimensional changes during the heat process during conductor drying, and allows the use of roll-to-roll methods, significantly improving green sheet handling in the ceramic circuit board manufacturing process. , it is possible to provide a high quality and inexpensive ceramic multilayer substrate. In addition, when processing via holes with laser light, irradiation is performed from the plastic film side, so even if chipping occurs around the via hole in the plastic film, the plastic film will be discarded in the later process, which will cause no inconvenience to the green sheet. There isn't. Therefore, with this configuration, a laser can be used for processing via holes, so productivity can be significantly improved. Furthermore, since the green sheet for multilayer boards is thin, this configuration is very effective because it protects it with a plastic film and improves lamination accuracy because dimensional changes are small even during the process where heat is applied. It is something.

[0008]

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

(1) The product name is Torelina manufactured by Toray Industries, Inc.
A film whose main component is polyphenylene sulfide,
Hereafter referred to as PPS. Its chemical structural formula is shown in (Chemical formula 1).

0010

[Chemical formula 1]

(2) Mitsubishi Plastics Co., Ltd.'s product name: Superio U
T is a film whose main component is polyetherimide, hereinafter referred to as PEI. Its chemical structural formula is shown in (Chemical formula 2).

0012

[Case 2]

(3) Product name TA manufactured by Mitsui Toatsu Chemical Co., Ltd.
LPA-1000 is a film whose main component is polyether sulfone, hereinafter referred to as PES. Its chemical structure is (
It is shown in Chemical formula 3).

[0014]

[Chemical formula 3]

(4) Product name TA manufactured by Mitsui Toatsu Chemical Co., Ltd.
LPA-2000, a film whose main component is polyetheretherketone, hereinafter referred to as PEEK. Its chemical structural formula is shown in (Chemical formula 4).

[0016]

[C4]

(5) Kapton, a product of DuPont Toray Co., Ltd., is a film whose main component is polyimide, hereinafter referred to as PI. Its chemical structural formula is shown in (Chemical formula 5).

[0018]

[C5]

(6) Product name Lumirror manufactured by Toray Industries, Inc.
A film whose main component is polyester, hereinafter referred to as PET. Its chemical structural formula is shown in (Chemical formula 6).

[0020]

[C6]

(7) A film obtained by subjecting the above PET film to a heat treatment at 100° C. or higher to achieve low shrinkage, hereinafter referred to as low shrinkage P
It's called ET. Its chemical structural formula is the same as (Chemical formula 6).

[0022] The properties of these seven types of plastic films are shown in (Table 1). With the properties shown in Table 1, the breaking strength and elongation rate were measured according to JIS-C2318, and the heat shrinkage rate was measured by making holes of 0.15 mmφ at 100 mm intervals, and determining the molding direction (MD) and the In the transverse direction (TD), the shrinkage ratio showed the largest value at n=4 after the heat treatment.

[0023]

[Table 1]

As shown in FIG. 1, these seven types of thickness are 7
A green sheet 1 necessary for manufacturing a ceramic circuit board is formed by forming a green sheet onto a 5 μm plastic film 5 so that the thickness after drying becomes 200 μm.
and plastic film 5 were made. Next, the green sheet is passed through an NC film through a plastic film.
A via hole with a diameter of 0.15 mm was punched. At this time, PET was prone to burrs, but the other films had excellent processability. The reason for this is related to the elongation rate (Table 1), and it can be easily inferred that the larger the elongation rate of the film at break, the more likely burrs will occur, and this is consistent with the results of actual experiments. Furthermore, it is expected that the smaller the breaking strength in Table 1, the better the workability and the longer the life of the pin during mass production. PEEK has a high elongation rate but a low breaking strength, so it has fewer burrs than PET.
It was at a sufficiently practical level. It has been found that engineering plastics, which generally have high heat resistance, have a low elongation rate and a low breaking strength, so they have excellent punching workability. Next, as shown in FIG.
Filled with via conductor 7a and dried at 90°C for 10 minutes,
A wiring pattern 7b was formed using a conductor on one surface of the green sheet, and was further dried at 90° C. for 10 minutes. Then, the green sheet 1 was peeled off from the plastic film 5, a plurality of green sheets having the wiring pattern formed thereon were laminated, and then fired to obtain a multilayer board. When we checked the reliability of the via connection, we found that only the one using PET film had a conduction failure, so we conducted a SEM observation of the cross section of the multilayer board to find the cause, and found that it was due to a misalignment of the via. Ta. This is thought to be due to the large shrinkage of the PET film during the drying process 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 become mainstream in the future with a diameter of 0.1 mm.If this happens, the reliability will be improved if the deviation of the via holes during stacking is 50 microns or less. This is necessary from the perspective of That is,
Approximately 90 degrees Celsius of heat is applied when drying the conductor, so please be careful about safety (
It is required that the value of the heat shrinkage rate at 100° C. or less in Table 1) is 0.05% or less. 0.05% of 100mm is 50 microns. In this experiment, compared to the conventional handling method described in the conventional example section, because the plastic film was placed, it was possible to easily handle the green sheet, which stretches easily and is easily torn. In addition, when drying a conductor, a single green sheet shrinks by more than 1%, whereas a composite of a green sheet and plastic film has a small dimensional change as shown in the heat shrinkage rate shown in Table 1 (Table 1). A ceramic circuit board with good stability, excellent reliability of via connections, and high density was obtained. In addition, since Tg is a physical property value that indicates the degree of heat resistance, the higher the Tg, the smaller the heat shrinkage rate, excluding some errors, and it is even more effective if the film is heat resistant to 85°C. It is clear from (Table 1) that the experimental results also agree. In addition, in the via filling process, generally a metal mask with a through hole slightly larger than the via hole is placed at the position corresponding to the via hole, and conductive paste is filled by printing from the metal mask side. However, after removing the metal mask, lands corresponding to the through holes in the metal mask were inevitably formed around the via holes. However, as shown in FIG. 3, when filling the via hole 6 with the via conductor 7a, filling the via land 12 by filling the via conductor 7a from the plastic film 5 side.
Even if this occurs, the via land 12 is removed when the plastic film 5 is peeled off from the green sheet 1.
As a result, the landless via 11 shown in FIG. 3 could be obtained, and a multilayer substrate with even higher density could be obtained.

(Example 2) In the via hole drilling process of Example 1, an experiment was conducted 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,
Although chipping 9 occurred, it was only on the surface of the plastic film 5, and there was no damage to the green sheet 1, and straight holes of 0.1 mm to 0.2 mm could be made. Among the seven types of films described in Example 1, there was almost no difference in laser perforation processability among the films. Furthermore, a multilayer board was produced in the same manner as in Example 1, and the reliability of via connections was the same as in Example 1, with no defects caused by the use of laser light. This experiment revealed that laser light could be used, which improved the productivity of hole-drilling, and also eliminated the problem of the lifespan of NC punches and mold pins, making it possible to significantly improve mass production. .

(Example 3) First, as in Example 1, the above 7
A green sheet was formed to a thickness of 200 μm on a plastic film having a thickness of 75 μm, and wound into a roll. Next, as shown in FIG. 5, the green sheet 1 with the plastic film 5 still attached is sequentially moved in the longitudinal direction, and in the moving process, the processing machine 10 is used to cut the green sheet 1 together with the plastic film 5. Via holes were formed and the film was sequentially wound. Similarly, after filling vias and forming wiring, the green sheet with the wiring pattern formed thereon is cut into a predetermined size along with the plastic film, the green sheet is peeled off from the plastic film, and a plurality of green sheets are cut. After laminating the sheets, firing was performed to obtain a multilayer substrate. In this experiment, a green sheet was rolled up for each process, but it goes without saying that it can be made continuous by considering the takt time of each process. By adopting this method, we solved the problem of handling green sheets, which tend to stretch and tear easily. In addition, it enables continuous production called roll-to-roll, and uses a plastic film with excellent heat resistance, which improves the lamination accuracy of multilayer boards and enables the creation of multilayer boards with excellent via connection reliability. became. In other words, since this method enables mass production and improves yield, it has been possible to manufacture inexpensive multilayer circuit boards in large quantities, and it has also been possible to bring out the possibility of introducing it into consumer devices. Above, Examples 1, 2, 3
Although the case of a multilayer board has been described above, it goes without saying that the present invention is also effective in the case of a circuit board in which only one green sheet is fired without stacking green sheets.

(Example 4) In order to obtain a high-density multilayer substrate, a ceramic material that matches well with the internal conductor was investigated. The first requirement for the substrate material is that it must be able to be fired at 900°C so that it can be fired simultaneously with conductor materials such as Ag and Cu that have low electrical resistance, as well as resistor and capacitor materials. Second, the dielectric constant is lower than that of the alumina substrate used in conventional HICs, that is, the dielectric constant is 9 or less. Thirdly, when co-fired with Ag and Cu internal conductors, it has excellent interlayer insulation, and there is no difference in shrinkage rate between areas with and without internal conductors. Interlayer reliability is 2x2mm between 200 micron insulation layers
85℃-85%RH in a constant temperature and humidity chamber.
Under this environment, after applying a voltage of 100V and leaving it for 1000 hours, I returned it indoors and measured the insulation resistance, which was 1010Ω.
The evaluation was made as ○ if the condition was maintained above that level, and as × if it was lower than that level. Regarding the deformation of the substrate, in order to express it quantitatively, the substrate deformation rate ΔL is defined as (Equation 1).

[0028]

[Math 1]

Here, Lc is the shrinkage rate of the substrate in the portion where the internal conductor is present, and Ld is the shrinkage rate in the portion without the internal conductor. If ΔL calculated as above is less than 0.5%, ○
gave a rating of Table 2 shows the composition of the substrate material that substantially satisfies the above conditions.

[0030]

[Table 2]

[0031] The compositions of glass A and glass B in the table (Table 3
).

[0032]

[Table 3]

First, for the mother glass, raw material batches prepared to have the glass compositions A and B shown in (Table 3) were placed in a platinum crucible and melted at 1500 to 1600°C for 2 to 3 hours, then placed in water and quenched. It was then ground in a ball mill until the average particle size was about 1.8 microns to obtain a mother glass powder. (Table 2) No. Nos. 1 to 5 were obtained by changing the mixing ratio of glass A powder and alumina powder from 60/40 to 40/60 by weight. Nos. 6 to 10 were obtained by changing the mixing ratio of glass B powder and alumina powder from 55/45 to 35/65 by weight. 11 to 13 are glass B powder and cordierite powder in a weight ratio of 60/40.
The mixing ratio was varied from ~45/55. These ceramic powders were molded into green sheets using an acrylic binder, and the above experiment was conducted. The results are shown in (Table 4).

[0034]

[Table 4]

Sample No. Regarding No. 10, the interlayer reliability was NG, but this was because 65 parts by weight of alumina powder, which is a filler component, was mixed with 35 parts by weight of glass powder, and sintering was not sufficient because the filler component was too large. It is considered that there was no such thing. That is, sample no. No.1 except 10. 1~
Composition range of each component of 13, Al2O3 13.97~
60% by weight, SiO2 22.8-56.52% by weight
, B2O3 2.32-5.1% by weight, Na2O
0.6-2.1% by weight, K2O 0.6-1.56% by weight, CaO 2.4-4.8% by weight, MgO 0.8
If the composition is selected so that the total amount is 100% by weight in the composition range of 4 to 8.53% by weight and 7.2 to 12% by weight of PbO, it has excellent reliability and has a higher internal resistance than conventional multilayer substrates. It was found that a high-density multilayer board with good matching properties with conductors could be obtained.

[0036]

Effects of the Invention As described above, the present invention is characterized in that a plastic film with a Tg of 85°C or higher is disposed on one side of a green sheet. The film protects the green sheet, which is prone to tearing and stretching, eliminates the need for extra jigs such as frames, minimizes dimensional changes during the heat process during conductor drying, and allows the roll-to-roll method to be used. The handling of green sheets in the manufacturing process is significantly improved, and a high quality and inexpensive ceramic multilayer substrate can be provided. In addition, when processing via holes with laser light, irradiation is performed from the plastic film side, so even if chipping occurs around the via hole in the plastic film, the plastic film will be discarded in the later process, which will cause no inconvenience to the green sheet. There is no. Therefore, with this configuration, a laser can be used for forming the via hole, so productivity can be significantly improved. Furthermore, since the green sheet for multilayer boards is thin, it has the effect of protecting it with a plastic film, and it also has the effect of improving lamination accuracy and improving the reliability of via connections because dimensional changes are small even during processes that apply heat. This configuration is very effective.

[Brief explanation of the drawing]

FIG. 1: A cross-sectional view of a composite of a green sheet and a plastic film in a first embodiment of the present invention.

[Figure 2] Cross-sectional view of a composite in one process of a ceramic circuit board using the same example

[Fig. 3] Cross-sectional view of a composite in another manufacturing process of a ceramic circuit board using the same example.

[Fig. 4] A cross-sectional view of a composite body showing still another manufacturing process of a ceramic circuit board using the same example.

[Fig. 5] A cross-sectional view of a composite showing still another manufacturing process of a ceramic circuit board using the same example.

[Fig. 6] A perspective view of a green sheet in one manufacturing process of a conventional ceramic circuit board.

[Figure 7] Cross-sectional view of a green sheet in another manufacturing process of a conventional ceramic circuit board

[Fig. 8] Cross-sectional view of a green sheet in another manufacturing process of a conventional ceramic circuit board

[Explanation 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 light 9 Chipping 10 Processing machine 11 Landless beer 12 Beerland

Claims (3)

[Claims] 1. A composite of a green sheet and a plastic film, characterized in that a plastic film having a glass transition temperature of 85° C. or higher is disposed on one side of the green sheet. 2. The green sheet according to claim 1, wherein the plastic film is a film containing any one of polyphenylene sulfide, polyetherimide, polyether sulfone, polyether ether ketone, and polyimide as a main component. and plastic film composite. Claim 3: The ceramic component of the green sheet is Al
2O3 13.97-60% by weight, SiO2 22.8
~56.52% by weight, B2O3 2.32-5.1% by weight, Na2O 0.6-2.1% by weight, K2O
0.6-1.56% by weight, CaO 2.4-4.8% by weight, MgO 0.84-8.53% by weight, PbO
A composite of a green sheet and a plastic film according to claim 1 or 2, characterized in that the composition is selected so that the total amount is 100% by weight in a composition range of 7.2 to 12% by weight.