JP4242623B2 - Method for manufacturing printed circuit board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a wiring board, in particular, a plurality of bumps for interlayer connection formed on one surface of a metal plate, for example, a copper plate (copper foil), and another metal plate, for example, a copper plate, or a wiring board. The wiring film, for example, a copper wiring film, is electrically connected by laminating and pressing a metal plate with bumps, another metal plate or a wiring board, and a member that forms a necessary insulating film for interlayer insulation. The present invention relates to a method for manufacturing a wiring board.
[0002]
[Prior art]
As a multilayer wiring circuit board manufacturing technique, the applicant company of the present application forms, for example, an etching barrier layer (thickness, for example, 1 μm) made of nickel, for example, on one main surface of a copper layer (thickness, for example, 100 μm) for projection formation. Furthermore, a multilayer wiring circuit board is obtained by using as a base a wiring circuit board forming member in which a copper foil (thickness, for example, 18 μm) for forming a conductor circuit is formed on the main surface of the etching barrier layer, and processing it appropriately. Developed technology to get
[0003]
6A to 6E are cross-sectional views showing the outline of such a technique in the order of steps.
(A) First, as shown in FIG. 6A, the wiring circuit board forming member (hereinafter simply referred to as “copper member”) a is prepared. The copper member a includes a copper layer (thickness, for example, 100 μm) b for forming a protrusion, an etching barrier layer (thickness, for example, 1 μm) c made of, for example, nickel, and a copper foil for forming a conductor circuit (thickness, for example, 18 μm). It has a cross-sectional structure in which d is laminated.
[0004]
(B) Next, as shown in FIG. 6B, a mask film e formed by selectively forming a resist made of a dry film on the surface of the wiring circuit forming copper layer b by exposure and development is used as a mask. The copper layer b is selectively etched to form bumps f for connecting the upper and lower wirings. g is a recess formed by the selective etching.
In this selective etching, the etching barrier layer c literally becomes an etching barrier and prevents the copper layer d for forming a conductor circuit from being etched.
[0005]
(C) Next, using a penetrating machine, a resin insulating sheet is placed on the surface of the member a on the side where the bumps f are formed, and the film is penetrated by the bumps f to fill the gaps between the bumps f. Form a state. FIG. 6C shows such a state, and h is an insulating layer made of the insulating sheet or the like and filling the gaps between the bumps f to provide interlayer insulation.
More specifically, the insulating layer is formed by polishing the bump forming surface side and polishing the upper surface of the bump f in a state where one or two release sheets are stacked on the insulating layer. Is called.
[0006]
(D) Next, as shown in FIG. 6D, a copper foil i for conductor circuit formation (thickness, for example, 18 μm) is laminated on the upper surfaces of the insulating layer h and the bump f, and integrated by thermocompression bonding. To do.
(E) Next, as shown in FIG. 6E, wiring films j and k are formed by selectively etching the upper and lower copper layers d and i.
As a result, a double-sided wiring board having wiring films j and k on both upper and lower surfaces and appropriately connecting the wiring films j and k with bumps f is formed. Further, a highly integrated wiring board having a large number of layers can be formed by stacking a plurality of such double-sided wiring boards.
[0007]
There are various variations in the wiring board formation technique using bumps as interlayer connection means, and several techniques have already been proposed. One variation is that, as shown in FIG. 7, a copper foil d having a bump f formed thereon, an insulating layer h, and a copper foil i are prepared, and the three members d, h, i are overlapped once. It is the method of laminating. In this case, by setting the pressure and temperature well, it is possible to prevent the insulating layer h from escaping from between the bumps f and the copper foil d and to prevent the electrical connection therebetween. It can be said that the number of manufacturing steps is small. It can be applied to an insulating resin that does not contain a glass substrate.
[0008]
By the way, this type of technique requires thermocompression bonding for electrical connection between a bump made of copper and a metal plate (metal foil). A press machine is used for the thermocompression bonding.
FIG. 8 is a cross-sectional view for explaining a method of thermocompression bonding using a conventionally used press. In the figure, reference numeral 2 denotes a heat plate, which is provided in a horizontal direction. 4 is a hydraulic cylinder mechanism that pressurizes the hot plate 2 upward in the vertical direction, and 6 is a hot plate, which is disposed above the hot plate 2 as appropriate. Each of the hot plates 2 and 6 has a path (not shown) through which heated oil circulates, and the workpiece can be heated during pressurization by circulating the heated oil through the path. Yes.
[0009]
.. Are press plates, a plurality of which are arranged between the hot plate 6 and the hot plate 2, and between the hot plate 6 and the uppermost press plate 10. In addition, a plurality of (for example, 10) objects to be pressed are arranged with a cushion material (for example, a plurality of kraft papers stacked) 14 interposed between the lowermost press plate 10 and the hot plate 2. . Each of the pressed members to be pressed is called a page. Therefore, 10 pages of the pressure object 12 are arranged between each. That is, the member a in FIG. 6 and the copper foil b are overlapped (or the members d, h, and i shown in FIG. 7 are overlapped) as one page, and 10 overlaps are 10 pages. It can be said that the object to be pressed that is overlapped by 10 pages is the object to be pressed to which the reference numeral 12 is given.
[0010]
And 10 pages of thermocompression bonding bodies 12 are between the hot plate 6 and the uppermost press plate 10, between the press plates 10 and 10, and between the lowermost press plate 10 and the hot plate 2. The hot plate 2 is moved to the upper side by the pressure cylinder 4 in a state of being arranged in each, and is further pressed (pressed) with a predetermined pressure to perform thermocompression bonding.
Accordingly, the thermocompression bonding of the thermocompression bonding body 12 of several tens of pages is performed by one press.
[0011]
[Problems to be solved by the invention]
By the way, there is a limit to the flatness of the press main body, the hot plate and the press plate in the conventional technique, and it is necessary to be prepared that irregularities of about ± 50 μm are generated in a normal press. Furthermore, when the temperature is high, the temperature is not constant in each part, and the flatness accuracy further decreases. For this reason, there is a problem that it is difficult to apply pressure uniformly to each part of the pressure-bonded body, the pressure is not uniformly applied to the laminated body, and the thickness becomes non-uniform.
FIGS. 9A to 9C are cross-sectional views showing such problems in an exaggerated manner. (A) shows the member d (bump f already formed), the insulating layer h, and the copper foil i to be thermocompression bonded, and (B) and (C) are cross-sectional views showing other inconvenient examples after thermocompression bonding. . As shown in FIGS. 9B and 9C, the non-uniformity in the thickness of the stacked body tends to be thicker at the portion where the bump f is formed at a higher density and thinner at the lower portion. For example, in the case where the thickness of the laminate is 100 μm, the thickness variation is ± 20 μm. Therefore, the bump f is formed at a high density, and the bump f and the copper foil i in the thick portion are not sufficiently crushed, resulting in incomplete bonding between the bump and the upper copper film.
[0012]
When the cause of the problem that the thickness of the laminated body becomes non-uniform is pursued, there is a slight gap between the hot plate 6 of the press machine, each of the press plates 10, 10,. However, there is a cause such as an inclination or a decrease in flatness of the surface of the hot plate 6 due to a temperature rise, but the biggest cause is a high bump arrangement density when the bump f arrangement density is uneven. It has been found that the portion requires a larger pressing force than the other portions, but the press plate is deformed and the pressing force escapes a considerable portion toward the cushion paper.
However, the arrangement of the bumps f is determined by the circuit configuration, and it is practically not permitted to require the uniformity of the arrangement density from the viewpoint of pressing.
[0013]
Therefore, the inventor of the present application has examined the use of an autoclave type pressurizing device for the technology for forming a wiring board using bumps as interlayer connection means. FIG. 10 shows an example of such a pressurizing apparatus. 20 is a pressure vessel, 22 is a fixed plate placed in the pressure vessel 20, and a member to be pressed 24 is placed on the fixed plate 22. . Reference numeral 26 denotes a heat-resistant bag covering the member to be pressed 24 on the fixed plate 22 and is made of, for example, a polyimide film. 28 and 28 are heaters for heating. The detailed configuration of the member to be pressed is the same as that shown in FIG. 8, but there is no hot plate 2, 6 or pressurizing mechanism 4.
[0014]
The press using the pressurizing apparatus pressurizes the member to be pressurized 24 with the heat-resistant bag 26 by evacuating the space inside the heat-resistant bag 26, and further supplies high-pressure gas into the pressure-resistant container 20. Then, the pressure applied to the member to be pressurized 24 is further increased by the gas pressure. Since such pressurization is a pressurization using a fluid (gas), there is an advantage that the pressurization force can be made uniform in any direction and in any part in the region where the pressurization force acts. Yes, in that respect, it can be said that it is excellent.
[0015]
However, the method using such an autoclave type pressure device has a problem that it is difficult to obtain a pressing force necessary to connect the bump and the copper foil.
This is because a general autoclave type pressurizing apparatus is designed to pressurize at a pressure of about 1 to 3 MPa, whereas the pressurizing force required to connect the bump and the copper foil is 3 to 10 MPa. This is because it is actually difficult to make a pressurizing device using the pressure vessel 20 that can withstand such pressure.
[0016]
Even without using an autoclave type pressurizing device, it is possible to obtain a good electrical connection between a bump and a metal plate such as a metal foil by pressing with a uniform pressure, and thus the thickness of the wiring board. The present inventors have sought a method for manufacturing a wiring board that can improve the uniformity of the present invention.
[0017]
That is, the present invention particularly includes a plurality of bumps for interlayer connection formed on one surface of a metal plate such as a copper plate (copper foil) and another metal plate such as a copper plate or a wiring film of a wiring board, For example, manufacturing a wiring board that performs electrical connection with a copper wiring film by laminating and pressing a metal plate with bumps, another metal plate or a wiring board, and a member that forms a necessary insulating film for interlayer insulation In the method, it is possible to obtain a good electrical connection between a bump and a metal plate such as a metal foil by applying pressure with a uniform applied pressure, and to increase the thickness uniformity of the wiring board. To do.
[0018]
[Means for solving the problems]
The method of manufacturing a wiring board according to claim 1, wherein the pressurizing is performed by attaching a pressurizing plate to the pressurizing main body so that a space for fluid pressure is formed therebetween, and supplying the fluid to the space. Using a press machine having a pressurizing unit that can pressurize the pressurizing plate and a stage that is opposed to the pressurizing plate and the relative distance from the pressurizing plate is adjusted, Each member constituting the printed circuit board to be pressurized is placed between the pressurizing plate and the stage so as to overlap each other, and one surface of the stack is placed on the pressurizing plate. This is performed by supplying a pressurizing fluid to the fluid pressure space in a state in which the surfaces of both are in contact with the stage.
[0019]
According to a second aspect of the present invention, there is provided a method of manufacturing a wiring board according to the first aspect, wherein the pressurizing unit body is filled with a liquid.
According to a third aspect of the present invention, there is provided a wiring board manufacturing method comprising: a metal plate having bumps to be laminated; another metal plate or a wiring board; and an insulating film for necessary interlayer insulation. Prepare a plurality of pressure-laminated areas arranged along a certain direction in a plurality of areas, and press the above-mentioned respective areas of each of the above-mentioned respective members by the above press machine. It is characterized by carrying out sequentially and continuously along the arrangement direction.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail according to embodiments shown in the drawings.
FIG. 1 is a cross-sectional view showing a press used for pressurization in the method for producing a wiring board of the present invention. In the figure, reference numeral 40 denotes a heat stage, 41 denotes a pressurizing unit, and includes members 42, 44, and 46 described below. Reference numeral 42 denotes a heat plate, which is provided above the heat stage 40 so as to be spaced apart from and parallel to the heat stage 40.
The hot plates 40 and 42 have a path (not shown) through which heating oil circulates, and the heated member is heated by circulating the heated oil through the path.
[0021]
Reference numeral 44 denotes a pressurizing main body portion made of, for example, a plate-like SUS (stainless steel) having a thickness of about 5 cm, and having a concave portion 48 having a depth of about 1 to 2 mm on the lower surface. The pressurizing main body 44 is formed with an oil passage hole 50 extending from the recess 48 and reaching the outer surface. A pressure plate 46 is made of, for example, SUS and has a thickness of, for example, about 1 to 2 mm. The pressure body 44 is sealed on the lower surface of the pressure body 44 with the above-described concave portion therebetween. The pressurizing space 48 is fixed so as to be formed. The pressurizing space 48 communicates with the hydraulic mechanism 54 through the oil passage hole 50 and the pipe 52 connected thereto, and oil is supplied from the hydraulic mechanism 54 at a predetermined pressure (for example, 100 MPa). The pressurizing space 48 can be supplied.
[0022]
56, 56,... Are press plates, a plurality of which are disposed between the pressurizing plate 46 and the thermal stage 40, and the press plate 46 and the top press. Between the plates 56, between the press plates 56, 56, and between the lowermost press plate 56 and the heat stage 40, a plurality (for example, 10) of objects to be pressed are arranged to overlap each other. Each of the pressed members to be pressed is called a page. Therefore, for example, 10 pages of objects to be pressed are arranged between each. That is, the member a in FIG. 6 and the copper foil b are overlapped (or the members d, h, and i shown in FIG. 7 are overlapped) as one page, and 10 overlaps are 10 pages. The code | symbol of 58 is given to the to-be-pressurized body of the 1 page.
[0023]
The 10-page thermocompression bonding body 58 includes the pressure plate 46 and the uppermost press plate 56, between the press plates 56 and 56, and the lowermost press plate 56 and the thermal stage 40. During this time, the pressurizing unit 41 is lowered by a pressurizing mechanism (not shown) in a state of being arranged in each, and these are applied to the heat stage 40 at a predetermined relatively weak first pressure (0.5 to 1.0 MPa). After that, thermocompression bonding is performed by further pressurizing with a predetermined strong second pressure (8 MPa) by hydraulic pressure by the hydraulic mechanism 54. At this time, the pressurizing mechanism 41 increases the pressure in conjunction with the second pressure so that the interval between the pressurizing unit 41 and the heat plate 40 is not opened by the second pressure.
Accordingly, the thermocompression bonding of the thermocompression bonding body 12 of several tens of pages is performed by one press.
In FIG. 1, the members 56, 56,... 58, 58,... Between the pressure plate 46 and the heat stage 40 are drawn with vertical intervals therebetween, that is, gravity. However, it is natural that these members are stacked on the thermal stage 40 in order to show each member in an easy-to-understand manner.
[0024]
Actually, when pressing, the pressurizing unit 41 is lowered as shown in FIG. 2, and at a predetermined first pressure (relatively weak as described above, for example, a pressure of about 0.5 to 1.0 MPa), As indicated by the arrow A, the thermal stage 40 is pressurized to the members 56, 56,... 58, 58,.
Next, while maintaining the pressurized state, the hydraulic device 54 further supplies oil into the pressurizing space 48 at a predetermined second pressure (an extremely strong pressure as described above, for example, about 8 MPa). At this time, the pressurizing mechanism 41 increases the pressure in conjunction with the second pressure so that the interval between the thermal stage 40 and the pressurizing unit 41 is not opened by the second pressure.
Then, since the second pressure depends on the fluid, a certain hydraulic pressure acts on the surface of the pressurizing plate, and the members 56, 56, ... Added to 58, 58,. The heating source is heated heating oil that circulates in the hot plate 42.
[0025]
According to such a press machine, the second pressure is applied by the hydraulic pressure of the oil supplied to the pressurizing space 48, so that the pressurizing plate 46 in contact with the pressurizing space 48 has the members 56, 56, .., 58, 58,..., With the upper surface of the rigid thermal stage 40 that does not deform at the normal operating pressure at which they are placed as a reference surface, each of the members 56, 56,. , 58, 58,..., So as to follow the surface, so that the uniformity of the press pressure can be remarkably improved. That is, even if the parallelism between the heat stage 40 and the pressure plate 46 is slightly low, the press pressure is uniform.
In the case of a normal press, the cushion paper absorbs the deformation of the press plate, but the force for restoring the deformation of the press plate is weak. However, in the case of this method, even if the pressure plate is deformed and dented in the bump dense area in the initial stage, if the bump is crushed by the pressure increase and the temperature rise, an equal pressure acts on the entire surface of the pressed member, In the case of a member to be pressed in which bumps are concentrated locally, there is a feature that it is finished flat.
[0026]
Specifically, in the case of a pressed member having a thickness of 100 μm in the past, the variation in thickness of ± 20 μm could be reduced to about ± 5 μm by using this press machine.
This is nothing but to say that the uniformity of the surface pressure can be increased to four times that of the prior art.
[0027]
FIG. 3 is a cross-sectional view schematically showing a second embodiment of the method for manufacturing a wiring board according to the present invention.
In this embodiment, for example, each member d (: copper foil with bump f), h (insulating film for interlayer insulation), i (: copper foil) shown in FIG. Are prepared in the form of a long object formed along the reels 60, 60, 60 and wound on different reels 60, 60, 60, and the long objects d, h, i from the reels 60, 60, 60 are prepared. Are stacked and passed between the heat stage 40 and the pressure part 41 of the press machine and heat-pressed with the press machine, and then the space between the heat stage 40 and the pressure part 41 is opened and the integrated part is wound up by heat-pressure bonding. The reel 62 is repeatedly wound up and then heat-pressed again with the press machine, and the heat-pressing is successively advanced.
In this way, since continuous thermocompression bonding is possible, thermocompression bonding can proceed smoothly and efficiently.
[0028]
FIG. 4 is a cross-sectional view showing another example of what can be subjected to thermocompression bonding by a press in the method for manufacturing a wiring board of the present invention. Although the thing shown in FIG. 7 was mentioned as an example which can become the object of the thermocompression bonding by the press in the manufacturing method of this invention wiring board, an object is not limited to it at all, A various thing can be object. FIG. 4 shows one example.
[0029]
In this example, a core wiring board 66 with double-sided wiring is placed in the middle, and a multilayer wiring board is formed by laminating wiring boards 64 and 64 with bumped interlayer insulating films formed on both main surfaces thereof. The core wiring board 66 is obtained by forming a wiring film j made of copper foil on both main surfaces of the insulating layer h, and k is a through hole formed in the wiring film j. Each of the wiring boards 64 and 64 is obtained by forming an interlayer insulating layer h on the surface of the copper foil d with the bump f on the bump f forming side, and the upper surface of each bump f of the wiring boards 64 and 64 is the core wiring board. A multilayer wiring board is obtained by connecting to the upper surface of each wiring film 66 of 66 by thermocompression bonding, and for example, a press shown in FIG. 1 or FIG. 3 is used for the thermocompression bonding. Such an aspect is also an embodiment of the method for manufacturing a wiring board of the present invention.
[0030]
In the above embodiment, the pressurizing unit is attached to the press main body as shown in FIG. 1, and the pressure is applied from the outside by using a hydraulic pressure adjusting machine. ) And (B) as shown in the perspective view and the cross-sectional view, the same effect can be defined even in a case where heat-resistant oil is sealed. The structure shown in (A) is that the pressure member 70 is heat resistant in a space formed in two metal plates, for example, SUS plates 73 and 73 having a thickness of 3 mm bound in the periphery. For example, a device for completely sealing the periphery by welding oil production 74 is prepared, and, for example, instead of the pressurizing unit shown in FIG. As a result, the oil pressure in the pressurizing body is generated as a reaction and the same oil pressure is generated, and the same effect is exhibited.
[0031]
In FIG. 5B, a frame 72 of the same material having a thickness of 1 mm is provided in the periphery of two metal plates, for example, SUS plates 73 and 73 having a thickness of 3 mm, and heat-resistant oil refining 74 is provided in the internal space. And a device that completely seals the periphery by welding, and is different from that shown in FIG.
[0032]
【The invention's effect】
According to the method for manufacturing a wiring board according to claim 1, each member constituting the wiring circuit board to be pressed is placed between the pressurizing plate and the stage of the press machine, Uniformity of the applied pressure is achieved by supplying a pressurizing fluid to the fluid pressure space with one surface of the stack being in contact with the pressure plate and the other surface being in contact with the stage. So that a good electrical connection can be obtained between the bump and a metal plate such as a metal foil by applying a uniform pressure, and the thickness of the wiring board is uniform. Can increase the sex.
[0033]
According to the method for manufacturing a wiring board according to claim 2, the pressurizing part, which is the independent plate of the press machine, is easy to handle and is easy to produce because of its simple mechanism. According to this manufacturing method, the same effect can be obtained.
[0034]
According to the method for manufacturing a wiring board according to claim 3, each member laminated by pressing is prepared in the form of a long object in which a pressing region is formed along one direction of a plurality of regions, and these members are, for example, mutually connected. It is wound up on different reels, and a long object-like member is piled up from each reel and passed between the stage and the pressurizing part of the press machine, and then pressed by the press machine, and then between the heat stage and the pressurizing part. It is possible to continuously pressurize by repeating the steps of opening and closing the integrated part by thermocompression with a take-up reel and then performing thermocompression with the press machine in order. it can. Therefore, pressurization can be smoothly and efficiently advanced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a press machine used for explaining a first embodiment of a method for manufacturing a wiring board according to the present invention.
FIG. 2 is a cross-sectional view showing a state at the time of pressurization by a press in the one embodiment.
FIG. 3 is a cross-sectional view of a press machine used for explaining a second embodiment of the method for manufacturing a wiring board of the present invention.
FIG. 4 is a cross-sectional view showing another example of what can be subjected to thermocompression bonding by a press in the method for manufacturing a wiring board of the present invention.
5A is a perspective view and a cross-sectional view showing another example of the pressurizing unit, and FIG. 5B is a perspective view and a cross-sectional view showing another example of the pressurizing unit.
6A to 6E are cross-sectional views illustrating a method for manufacturing a multilayer wiring circuit board in the order of steps.
FIG. 7 is a cross-sectional view showing another example of members stacked and integrated by pressing.
FIG. 8 is a cross-sectional view showing a conventional example of a press used for pressurization.
FIGS. 9A to 9C are cross-sectional views showing the problems of the prior art, FIG. 9A is a problem before pressure lamination, and FIGS. 9B and 9C are problems after pressure lamination. Here is another example.
FIG. 10 is a cross-sectional view of an autoclave type pressure device.
[Explanation of symbols]
40 ... Stage, 41 ... Pressure part, 42 ... Heat plate, 44 ... Pressure body, 46 ... Pressure plate, 48 ... Pressure space part, 54 ...・ Pressure device, 56... Pressure plate, 58, 64, 66.

Claims (4)

Electrical connection between a plurality of bumps for interlayer connection formed on one surface of the metal plate and another metal plate or a wiring film of the wiring board is made by connecting the metal plate with the bump, another metal plate or In a method of manufacturing a wiring board, which is performed by laminating and pressurizing a wiring board and an insulating film for necessary interlayer insulation,
The above pressurization
A pressurizing part attached to a pressurizing body part so that a space for fluid pressure is formed between the pressurizing platen and supplying the fluid to the space part so that the pressurizing platen can be pressurized; A stage that faces the pressure plate and can adjust a relative distance from the pressure plate, and a pressure mechanism that applies pressure by bringing the stage close to the pressure plate. Using a press machine
Between the pressurizing plate and the stage, each member constituting the printed circuit board to be pressed is placed in an overlapping manner,
With the pressurizing mechanism bringing the pressurizing unit in close proximity to the stage, with one surface of the stack being in contact with the pressurizing plate and the other surface being in contact with the stage, the first pressure Pressurizing each member,
Then, a pressurizing fluid is supplied to the fluid pressure space and the respective members are pressurized with a second pressure larger than the first pressure. Method. The method of manufacturing a multilayer printed circuit board according to claim 1, wherein the pressurizing unit main body uses a liquid sealed inside. Each member to be laminated and pressed, such as a metal plate with bumps to be laminated, another metal plate or wiring board and an insulating film for necessary interlayer insulation, is a continuous long object,
The method for manufacturing a multilayer printed circuit board according to claim 1 or 2, wherein the members of the long object are intermittently introduced into the press machine and the pressing is performed sequentially and continuously. The first pressure is included in a range of 0.5 MPa to 1.0 MPa;
The method for manufacturing a multilayer printed circuit board according to any one of claims 1 to 3, wherein the second pressure is 8 MPa.

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