JP3876802B2 - Press method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a press method suitable for manufacturing a multilayer substrate formed by laminating a plurality of resin films on which conductor patterns are formed and heating and pressurizing the laminate of the resin films.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a method for producing a multilayer substrate, a method of producing a multilayer substrate by laminating resin films on which conductor patterns are formed and applying pressure while heating them is known.
[0003]
For example, according to the method for manufacturing a multilayer substrate disclosed in Patent Document 1, first, a conductive pattern is formed on both surfaces of a resin film made of a thermoplastic resin, and a plurality of double-sided substrates in which the conductive patterns on both surfaces are interlayer-connected with a conductive paste are provided. Manufacture sheets. Next, the plurality of double-sided substrates are laminated via a thermoplastic resin film that has been subjected to interlayer connection processing. Then, the laminated double-sided substrate and the resin film are heated by passing an electric current through a press die made of a conductive metal such as titanium, and the generated die is pressed against the laminated resin film. By applying a predetermined pressure to the thermoplastic resin, the thermoplastic resin is softened and bonded. However, when the press die is directly pressed against the resin film and heated and pressurized, the conductor pattern formed on the resin film is likely to be displaced. Therefore, the present applicant has proposed in Patent Document 2 to provide a buffer member for suppressing the displacement of the conductor pattern between the press die and the resin film. Further, when the heated and pressurized press die is pressed against the resin film through the buffer member, in order to improve the mold release property between the buffer member and the resin film, one sheet of separation is required between the buffer member and the resin film. Proposed to provide a mold film.
[0004]
[Patent Document 1]
JP 2000-38464 A
[Patent Document 2]
Japanese Patent Application No. 2002-100113 [0006]
[Problems to be solved by the invention]
However, when the release film and the resin film are brought into close contact with each other by pressing the press die, the peeling strength for peeling from the resin film is increased even in the release film. Furthermore, since the release film is in close contact with the buffer member, the release film needs to be peeled off from the resin film together with the buffer member.
[0007]
Therefore, when a hard member having a high elastic modulus is used as the buffer member, it takes time and man-hours to peel off the release film from the resin film on the surface of the multilayer substrate, and there is a problem that productivity is lowered.
[0008]
In view of the above problems, an object of the present invention is to provide a press method with improved productivity.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the press method according to claim 1 includes a pattern forming step of forming a conductor pattern on at least one surface of a resin film made of a thermoplastic resin, and a plurality of resin films including the resin film provided with the conductor pattern. A laminating process for laminating resin films, and a heating / pressurizing process for bonding the resin films to each other to form a multilayer substrate by applying pressure while heating the laminate of the resin films using a press die. Yes. In the heating / pressurizing step, a buffer member for reducing a pressure difference applied to each part of the laminate of the resin film from the press die is interposed between the laminate and the press die. Between the members, at least two resin films of a laminate and a hard-to-wear and flexible release film are provided.
[0010]
The cause of the positional deviation of the conductor pattern formed on the resin film is described in Japanese Patent Application No. 2002-100113. Although detailed explanation is omitted, the press die is pressed against the resin film in a heated and pressurized state. Then, the pressure concentrates on the convex portion of the resin film and the portion having a large resistance to the pressure of the press die, and the flow amount of the thermoplastic resin at that portion increases. As a result, the conductor pattern formed thereon also moves, causing a positional shift.
[0011]
As a countermeasure, a cushioning member that can be deformed corresponding to the part with a large resistance to the unevenness of the resin film surface and the pressure of the press mold in the laminated resin film is placed between the press mold and the resin film. did. As a result, occurrence of displacement of the conductor pattern can be prevented. Under the present circumstances, if a release film is arrange | positioned between a buffer member and a resin film, adhesion | attachment with a resin film and a buffer member can be prevented. However, it takes labor and time to peel off the release film together with the buffer member, which has been a factor in reducing productivity.
[0012]
Therefore, as described in claim 1, at least two release films are disposed between the resin film and the buffer member. As a result, one surface of each release film is in contact with the other release film, so the adhesive force between the release films is weak, and the release films are easily peeled off after heating and pressurization. be able to. Therefore, since only one release film remains on the resin film surface of the formed multilayer substrate, the release film can be more easily peeled off from the resin film surface than when both the buffer members remain. it can. As a result, the labor for taking out the multilayer substrate from the press mold after the multilayer substrate is formed and the working time are reduced, and the productivity can be improved.
[0013]
According to a second aspect of the present invention, the buffer member is preferably a metal fiber, glass fiber or resin fiber formed into a plate shape, or a plate rubber. As a result, when the buffer member cushions the unevenness on the surface of the resin film or there is a difference in the resistance force in the compression direction of the resin film, a part of the buffer member can be deformed and the pressure difference can be reduced. It becomes.
[0014]
According to a third aspect of the present invention, the buffer member obtained by forming a metal fiber, a glass fiber, or a resin fiber into a plate shape may be wrapped with one of at least two release films. In this case, it is possible to prevent the dust of the fibers of the buffer member from adhering to the resin film on which the conductor pattern is formed during the heating and pressurization as well as the productivity.
[0015]
As described in claim 4, the release film preferably has a melting point higher than the heating temperature in the heating / pressurizing step. Thereby, it can prevent that a release film welds with a resin film at the time of a heating and pressurization.
[0016]
Preferably, the at least two release films are made of different materials. For example, when two release films are formed of different materials, the amount of shrinkage due to heat during heating and pressurization differs, and shear stress acts between the release films. Therefore, since the release films can be easily peeled off after the heating / pressurizing step, only one release film remaining on the resin film surface of the multilayer substrate is peeled off, and the surface of the multilayer substrate is easier than before. The release film can be peeled off.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view for each process showing the manufacturing process of the multilayer substrate in the present embodiment.
[0018]
As shown to Fig.1 (a), 1 is the single-sided conductor pattern film which has the conductor pattern 3 which patterned the conductor foil stuck on the single side | surface of the resin film 2 by the etching. Here, as the resin film 2, for example, a resin film having a thickness of 25 to 100 μm composed of 65 to 35% by weight of polyetheretherketone (PEEK) which is a thermoplastic resin and 35 to 65% by weight of polyetherimide (PEI). Can be used. Further, as the conductor foil, for example, a low resistance metal foil containing at least one of Au, Ag, Cu, and Al is preferable, and a Cu foil that is inexpensive and does not cause migration is preferable. The formation of the conductor pattern 3 may be performed using a printing method other than etching of the conductor foil.
[0019]
When the step of forming the conductor pattern 3 on the resin film 2 in FIG. 1A is completed, next, as shown in FIG. 1B, for example, a carbon dioxide laser is irradiated from the resin film 2 side to form a conductor pattern. A via hole 4 that is a bottomed hole having a bottom surface 3 is formed. For the formation of the via hole 4, it is possible to use a UV-YAG laser, an excimer laser or the like in addition to the carbon dioxide laser. In addition, it is possible to form via holes mechanically by drilling or the like, but since it is necessary to process so as not to damage the conductor pattern 3 with a small diameter, a laser processing method should be selected. Is preferred.
[0020]
When the formation of the via hole 4 is completed, as shown in FIG. 1C, the via hole 4 is filled with a conductive paste 5 that is an interlayer connection material. The conductive paste 5 is a paste obtained by adding an organic solvent to metal particles such as Cu, Ag, Sn, and kneading them. In addition, the conductive paste 5 may be additionally mixed with a low melting point glass frit, an organic resin, or an inorganic filler as appropriate. The conductive paste 5 is filled into the via hole 4 using a screen printing machine, a dispenser or the like (not shown).
[0021]
When the filling of the conductive paste 5 into the via hole 4 is completed, a plurality of single-sided conductor pattern films 1 are stacked (four in this example) as shown in FIG. At this time, of the four single-sided conductor pattern films 1, the upper two sheets have the conductor pattern 3 formed on the upper side, and the lower two sheets have the conductor pattern 3 formed on the center of the lamination. Laminate so that the surface is on the bottom
[0022]
Thus, in this Embodiment, a multilayer substrate is comprised only with the single-sided conductor pattern film 1. FIG. Therefore, the manufacturing equipment and the manufacturing process can be simplified, and the manufacturing cost can be reduced. In addition, since the electrodes of the conductor pattern 3 are formed on the upper and lower surfaces of the multilayer substrate, high-density mounting or a reduction in size of the multilayer substrate can be achieved.
[0023]
As shown in FIG. 1 (d), after the lamination process of laminating four single-sided conductor pattern films 1, a multilayer substrate is formed by heating and pressing from the upper and lower surfaces of the laminate with a press die of a heating press. A heating / pressurizing step is performed. Through the above-described manufacturing process, each resin film 2 is thermally welded and integrated, and an interlayer connection is made between the adjacent conductor pattern 3 or the conductive paste 5 by the conductive paste 5 in the via hole 4. A multilayer substrate 6 is formed as shown in FIG.
[0024]
Next, the heating / pressurizing step will be described in detail with reference to FIG.
[0025]
In FIG. 2, 7a and 7b are a pair of press type | molds, and are arrange | positioned so that the several sheets of single-sided conductor pattern film 1 may be pinched | interposed from the up-and-down both sides of the laminated body laminated | stacked. The press dies 7a and 7b are made of, for example, a conductive metal such as titanium, and generate heat when a current is applied. In addition, a heater is embedded in the press dies 7a and 7b and heated by the heater, or a fluid circulation path is provided in the press dies 7a and 7b, and the heated fluid is allowed to flow in the circulation path. Thus, the press dies 7a and 7b may be heated.
[0026]
The pressure application surface of the press dies 7a and 7b to the single-sided conductor pattern film 1 is flat. When the single-sided conductor pattern film 1 on which the press dies 7a and 7b are directly laminated is heated and pressurized, the press dies 7a and 7b A difference may arise in the pressure applied to each part of a laminated body by the unevenness | corrugation of the single-sided conductor pattern film 1 which touches, and the unevenness | corrugation of the inner layer of a laminated body. As a result, the flow amount of the resin film 2 in the portion that is strongly subjected to pressure increases more than the flow amount in the other portions, and the positional deviation of the conductor pattern 3 occurs. Furthermore, if a gap occurs between the single-sided conductor pattern films 1 due to the flow and voids are generated in the formed multilayer substrate 6, problems such as delamination may occur.
[0027]
For this reason, buffer members 8a and 8b having a buffering effect and a ventilation effect are provided between the press dies 7a and 7b and the single-sided conductor pattern film 1, and the press dies 7a and 7b are provided via the buffer members 8a and 8b. Heating and pressurization were performed.
[0028]
Here, as a material used as the buffer members 8a and 8b, a metal such as stainless steel is cut into a fiber shape, and the fiber metal is formed into a plate shape as a nonwoven fabric, or a woven fabric is a knit or cloth ( Generally, a so-called NASRON knit or NASRON cloth) can be used. In addition, the buffer members 8a and 8b have a resistance higher than the heating and pressurizing process conditions described later, and have a shape that can buffer the shape difference between the mold surfaces of the press dies 7a and 7b and the single-sided conductor pattern film 1. As long as it has the flexibility which can be elastically deformed, the thing of another material and a structure may be sufficient. For example, a polytetrafluoroethylene film, a Kepler, or a hypersheet gasket obtained by special processing of a polytetrafluoroethylene resin, a film or fiberized resin, glass fiber, or the like can be used. Furthermore, when the air between the single-sided conductor pattern films 1 is excluded in advance by storing in a decompression container or the like, it is sufficient to exhibit only a buffering effect, so a heat-resistant rubber sheet or the like may be used. it can. The heating and pressurizing conditions applied to the single-sided conductor pattern film 1 by the press dies 7a and 7b are, for example, a temperature in the range of 200 to 350 ° C., and a pressure in the range of 0.1 to 10 MPa. Value.
[0029]
By using the buffer members 8a and 8b having the above-described buffer effect, even if the surface of the laminated single-sided conductor pattern film 1 has irregularities, the buffer members 8a and 8b are deformed according to the irregularities. Pressure is applied to the pattern film 1 almost evenly, and as a result, displacement of the conductor pattern 3 can be prevented.
[0030]
Here, conventionally, in order to improve the releasability between the single-sided conductor pattern film 1 and the buffer members 8a and 8b in the heating / pressurizing step between the single-sided conductor pattern film 1 and the buffer members 8a and 8b. In addition, one release film such as polyimide resin was disposed between the two.
[0031]
However, as shown in FIG. 2, in this embodiment, two release films (a total of four sheets) 9a, 9b, 9c are provided between the single-sided conductor pattern film 1 and the cushioning materials 8a, 8b. 9d. Below, the effect is demonstrated using FIG. 3, FIG. 3 and 5 both show a state in which the multilayer substrate 6 is formed by the heating / pressurizing process, FIG. 3 is a sectional view showing the conventional example, and FIG. 5 is a sectional view showing the present embodiment.
[0032]
The release films 9a to 9d are made of polyimide and transmit air. In addition, even if the thermoplastic resin of the resin film 2 constituting the single-sided conductor pattern film 1 is softened by heating and pressurization, the melting temperature of the polyimide is higher than that temperature, and the elastic modulus decreases with increasing temperature. Since it is small, the resin film 2 is difficult to adhere. Furthermore, since each of the release films 9a to 9d has a thickness of 100 μm or less and is very thin, the release films 9a to 9d can be bent along with the unevenness on the surface of the single-sided conductor pattern film 1. In addition, as the release films 9a to 9d, a high heat resistant resin such as polytetrafluoroethylene can be used in addition to polyimide.
[0033]
Here, conventionally, as shown in FIG. 5, only one release film 9 a is arranged between the buffer member 8 a and the multilayer substrate 6. At this time, particularly when the buffer member 8a has a high elastic modulus and is made of a hard material, the buffer member 8a is deformed together with the unevenness on the surface of the single-sided conductor pattern film 1 when heated and pressed by the press die 7a. At this time, the release film 9 a is strongly pressed against the surface of the single-sided conductor pattern film 1. Therefore, the resin surface of the multilayer substrate 6 and the buffer member 8a are both in close contact with the release film 9a, and the release film 9a is further released from the resin surface of the multilayer substrate 6, and the buffer member 8a is further released from the release film 9a. It takes considerable effort and time to peel off. In some cases, the release film 9a may be torn or the buffer member 8a or the multilayer substrate 6 may be damaged.
[0034]
Therefore, as shown in FIG. 3, two release films were provided between the buffer member 8 a and the multilayer substrate 6. Similarly to the above, when a hard material having a high elastic modulus is used as the buffer member 8a, one surface of the release film 9b is strongly pressed against the surface of the single-sided conductor pattern 1, but the other surface is the release film. It is in contact with 9a. The release film 9a also has one surface in contact with the buffer member 8a, while the other surface is in contact with the release film 9b. Since the adhesive force between the release films 9a and 9b is weaker than that between the release film 9b and the resin film 2 of the multilayer substrate 6, it can be easily peeled off. Then, only the release film 9b remains on the resin surface of the multilayer substrate 6, and the release film 9b is flexible and can be bent easily, so that it is easy to bend from the resin surface while bending the release film 9b. Can be peeled off. Therefore, by providing two release films 9a and 9b between the buffer member 8a and the multilayer substrate 6, the work of taking out the multilayer substrate 6 from the press dies 8a and 8b is facilitated, and the man-hour and work time are reduced. Therefore, productivity can be improved.
[0035]
The two release films 9a and 9b are preferably formed from different materials. In this case, since the amount of heat shrinkage between the release films 9a and 9b in contact with each other is different, shear stress is generated between the films 9a and 9b during heating and pressurization. Accordingly, the release films 9a and 9b after the multilayer substrate 6 is formed can be easily peeled off, and the productivity can be further improved. Although not shown in FIG. 3, the release films 9c and 9d are the same as described above.
[0036]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
[0037]
Since the press method in the second embodiment is often in common with that in the first embodiment, the detailed description of the common parts will be omitted below, and the different parts will be described mainly.
[0038]
The second embodiment is different from the first embodiment in that one release film is arranged so as to cover the buffer member.
[0039]
As shown in FIG. 4, the buffer members 8a and 8b are covered with resin covers 10a and 10b made of a thermoplastic resin. In the present embodiment, metal fibers, glass fibers, resin fibers, and the like can be used as the buffer members 8a and 8b, as in the first embodiment. Therefore, the resin covers 10a and 10b can prevent the fiber scraps and the like of the buffer members 8a and 8b from adhering to the single-sided conductor pattern film 1. Moreover, when performing a heating and pressurizing process in a vacuum atmosphere, since fiber waste is not discharge | released, there also exists an advantage that the filter of a vacuum pump is not soiled.
[0040]
At this time, since the resin covers 10a and 10b are made of a thermoplastic resin, the resin covers 10a and 10b are prevented from adhering to the press dies 7a and 7b during heating and pressurization, and the buffer members 8a and 8b and the single-sided conductor pattern film are used. In order to have the role of one release film between the two, the release films 9a and 9d are provided so as to cover the resin covers 10a and 10b.
[0041]
As described above, the release films 9a and 9d are provided so as to cover the buffer members 8a and 8b, and separately, between the buffer members 8a and 8b and the single-sided conductor pattern film 1 wrapped in the release films 9a and 9d. The release films 9b and 9c are arranged. Thereby, after the heating / pressurizing step, the release films 9b and 9c can be easily peeled off from the surface of the formed multilayer substrate 6, so that productivity can be improved also in this embodiment.
[0042]
In the present embodiment, the buffer members 8a and 8b are covered with the resin covers 10a and 10b, and the release sheets 9a and 9d are further provided so as to cover them. However, the resin covers 10a and 10b are The buffer members 8a and 8b may be directly covered with the release sheets 9a and 9d for use.
[0043]
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made.
[0044]
In the above-described embodiment, the resin film is a thermoplastic resin film composed of 65 to 35% PEEK resin and 35 to 65% PEI resin. However, PEEK and PEI can be used alone. Furthermore, polyethersulfone (PES), polyphenylene ether (PPE), polyethylene naphthalate (PEN), liquid crystal polymer, styrenic resin having a syndiotactic structure, etc. may be used alone, or PEEK and PEI may be used. Any one of them may be mixed and used. In short, in the heating / pressurizing step, resin films can be bonded to each other, and any resin film having heat resistance necessary for soldering or the like, which is a subsequent step, can be suitably used.
[0045]
Moreover, in this Embodiment, although the example which laminates | stacks the single-sided conductor pattern film in which the conductor pattern was formed on one side was shown as a resin film, a single-sided conductor pattern film was used for the upper and lower sides other than that using a core board | substrate. Alternatively, a processed resin film made of a thermoplastic resin having a conductor pattern formed on both sides may be used instead of the core substrate. Moreover, in the resin film laminated | stacked, you may include the resin film which does not have a conductor pattern on the surface.
[0046]
In the present embodiment, an example of a printing method in which a conductive paste is filled in a via hole is shown. However, electroless plating, electrolytic plating, vapor deposition, metal coating, or the like may be used.
[0047]
Further, in the present embodiment, a bottomed via hole is formed, and the bottomed via hole is filled with a conductive paste which is an interlayer connection material. A through hole is formed at the time of forming the via hole, and the interlayer connection material is formed in the through via hole. May be used.
[0048]
Moreover, in this Embodiment, although the example which laminates | stacks four single-sided conductor pattern films containing a resin film was shown, it cannot be overemphasized that the number of layers will not be limited if it is two or more.
[0049]
Further, in the present embodiment, an example in which the buffer member covered with the resin cover is further wrapped with one release sheet has been shown. A release film may be disposed between the member and the other release film.
[0050]
Further, in the present embodiment, an example in which two release films are attached to one buffer member is shown, but it is sufficient that at least two release films are used. What is necessary is just to set in the range which can be deformed to such an extent that it can be set.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view for each manufacturing process of a multilayer substrate in the present embodiment.
FIG. 2 is a cross-sectional view for explaining a heating / pressurizing step in the first embodiment.
FIG. 3 is a cross-sectional view for explaining the function and effect of the release film.
FIG. 4 is a cross-sectional view for explaining a heating / pressurizing step in the second embodiment.
FIG. 5 is a cross-sectional view for explaining a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Single-sided conductor pattern film, 2 ... Resin film, 6 ... Multilayer substrate, 7a, 7b ... Press type | mold, 8a, 8b ... Buffer member, 9a, 9b, 9c, 9d ...・ Release film, 10, 10b ... resin cover

Claims (5)

A pattern forming step of forming a conductor pattern on at least one surface of a resin film made of a thermoplastic resin;
A laminating step of laminating a plurality of resin films including a resin film provided with the conductor pattern;
A heating / pressurizing step of forming a multilayer substrate by bonding the resin films to each other by pressurizing while heating the laminate of the resin films using a press mold,
In the heating / pressurizing step, a buffer member for reducing a pressure difference applied to each part of the laminate of the resin film from the press die is interposed between the laminate and the press die, and the resin A pressing method characterized by providing at least two resin films of the laminate and a hard-to-bond and flexible release film between the film surface and the buffer member. 2. The press method according to claim 1, wherein the buffer member is a metal fiber, glass fiber or resin fiber formed into a plate shape, or a plate rubber. 3. The press method according to claim 2, wherein the buffer member formed of a metal fiber, a glass fiber, or a resin fiber in a plate shape is wrapped with at least one of the two release films. The press method according to any one of claims 1 to 3, wherein the release film has a melting point higher than a heating temperature in the heating / pressurizing step. The press method according to any one of claims 1 to 4, wherein the at least two release films are made of different materials.

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