JP2001287300A - Copper-clad laminated substrate and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper-clad laminated substrate which has a predetermined thickness and a predetermined precision of thickness obtainable in an easy way without generating a bubble and shows an excellent dielectric property and to provide its manufacturing method. SOLUTION: A copper-clad laminated substrate is provided with a plate- shaped formed item 1 formed by using a thermoplastic resin and copper foils 2 laminated on both surfaces of the plate-shaped formed item 1, wherein the lamination surface 3 of each copper foil 2 is subjected to surface roughening treatment and is bonded to each of both surfaces of the plate-shaped formed item without an adhesive layer between them. A dielectric property of the base material can be enhanced since the copper foil 2 is directly bonded to the plate-shaped formed item 1 formed in a high precision to eliminate use of a reinforcement such as a glass cloth or the like which deteriorates the dielectric property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-clad laminate used for a printed wiring board and a method of manufacturing the same, and more particularly, to a copper-clad laminate useful for antennas and high-frequency filters whose dielectric properties greatly affect product performance. TECHNICAL FIELD The present invention relates to a laminated substrate and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventional copper-clad laminated substrates (copper c)
lad laminate), as shown in FIG.
Thermosetting resin 10 and fiber-reinforced material 1 such as glass cloth
1 and a copper foil 2 laminated on one or both sides of the plate-shaped molded body 1 and used as an insulating base material of a printed wiring board. Although such copper-clad laminates are excellent in heat resistance and strength,
Since the dielectric properties of the reinforcing material 11 are deteriorated due to its high dielectric constant and dielectric loss tangent, it is not suitable as an insulating base material of a printed wiring board requiring excellent high-frequency characteristics. Also,
Although a high dielectric constant is required depending on the application, in order to satisfy this requirement, it is necessary to mix a large amount of ceramic filler. However, it is practically impossible to impregnate the reinforcing material 11 with such a material.

In view of the above, an attempt has been made to produce an insulating base material using only a thermoplastic resin component or a resin component and a filler having a high dielectric constant without using a reinforcing material 11 made of fiber such as glass cloth. ing.

[0004]

However, the reinforcing material 11 for the copper-clad laminated substrate regulates the flow of the resin material during hot pressing when the copper foils 2 are laminated, so that the copper-clad laminated substrate has a predetermined thickness. It has a function to make it easy. Therefore, when an insulating base material is to be produced using only a thermoplastic resin component or a resin component and a filler having a high dielectric constant without using a fiber reinforcing material 11 such as a glass cloth, the flow of the resin material is restricted. There is a problem that you can not. There is also a method of arranging spacers around the periphery, but with this method, it is very difficult to obtain a predetermined thickness and thickness accuracy. In particular, crystalline thermoplastic resin, although excellent in heat resistance,
The viscosity at the time of melting is low, and it is extremely difficult to obtain a predetermined thickness and thickness accuracy. In addition, since the pressure is concentrated on the spacer, there is a disadvantage that air bubbles are easily generated in the product.

As a method of solving such a problem, there has been proposed a method of laminating the copper foil 2 using an adhesive which exhibits an adhesive property in a range where the thermoplastic resin does not show flow. However, thermoplastic resins having high heat resistance have poor adhesiveness to other resin materials, and it is very difficult to match the dielectric properties even if an appropriate adhesive is present. Therefore, in such a method, the dielectric characteristics of the substrate are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is possible to obtain a predetermined thickness and a thickness accuracy by a simple method without generating bubbles, and to obtain excellent dielectric characteristics as a substrate. It is an object of the present invention to provide a copper-clad laminated substrate and a method of manufacturing the same.

[0007]

According to the first aspect of the present invention, in order to achieve the above object, a copper foil is laminated on at least one surface of a plate-like molded body made of a thermoplastic resin. The laminated surface of the foil is subjected to a roughening treatment, and the laminated surface of the copper foil is directly bonded to at least one surface of the plate-shaped molded body without using an adhesive.

In order to achieve the above object, in the invention according to claim 2, a laminated surface obtained by roughening a copper foil is superposed on at least one surface of a plate-shaped molded body made of a thermoplastic resin.
Along with applying a predetermined pressure at a temperature lower than the flow temperature of the thermoplastic resin to these plate-shaped molded products and the copper foil, increasing the temperature at a predetermined speed, and cooling when the pressure is reduced, the above-mentioned plate-shaped molded products and It is characterized by bonding with copper foil. That is, the present inventors use a resin material having no means for controlling the flow of the resin, and provide a copper-clad laminated substrate having a predetermined thickness and a thickness accuracy by a simple method without impairing the dielectric characteristics of the resin material. In order to obtain, a copper foil was directly adhered to the plate-shaped molded article, and various investigations were repeated on the structure and manufacturing method. As a result, it was confirmed that by adopting the above configuration and manufacturing method, it was possible to obtain a predetermined thickness and thickness accuracy by a simple method, and to obtain a copper-clad laminated substrate having excellent dielectric properties. The present invention has been completed.

According to the present invention, since the copper foil is directly bonded to the plate-like molded body molded with high precision, a reinforcing material and the like can be omitted. Therefore, deterioration of the dielectric characteristics can be suppressed and prevented, and excellent high-frequency characteristics can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. A copper-clad laminate according to this embodiment is molded using a thermoplastic resin as shown in FIG. A plate-like molded body 1 and copper foils 2 laminated on both sides of the plate-like molded body 1, respectively, and a lamination surface 3 which is a mat surface of each copper foil 2 is subjected to a roughening treatment. The lamination surface 3 of the copper foil 2 is directly adhered to both surfaces of the substrate 1 without using an adhesive.

As the thermoplastic resin forming the plate-like molded body 1, a thermoplastic resin generally called an engineering plastic is selected because a printed wiring board is required to have mechanical strength and heat resistance. Specifically, polyphenylene sulfide (PPS), polyphenylene ether
(PPE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), syndiotactic polystyrene (S
PS), polyarylate, liquid crystal polymer, polyethersulfone (PES), polyetheretherketone (P
EEK), polyacetal and the like. Various additives such as a softening agent and a processing aid are appropriately added to these resins as needed.

Further, addition of various fillers such as a reinforcing filler and a dielectric constant adjusting filler is optional. The filler used here is not particularly limited, but it is preferable to select a filler having a size that can be inserted between the irregularities of the roughened laminated surface 3 of each copper foil 2. By doing so, the uniformity of the components of the insulating base material can be maintained. In the filler having a reinforcing effect,
The adhesive strength of each copper foil 2 can be improved.

As each copper foil 2, an electrolytic copper foil, a rolled copper foil, or the like is appropriately selected according to the specification and purpose of the printed wiring board to be finally used. The entire laminated surface 3 of each of the copper foils 2 overlapping both surfaces of the plate-shaped molded body 1 is roughened to have irregularities, and exhibits an anchor effect. The surface roughening process is, specifically, a reddening process,
Alternatively, depending on the plating method, copper or copper alloy can be in the form of bumps, needles,
This is achieved by precipitation in a dendritic manner or the like. It can also be achieved by using a commercially available copper foil 2 subjected to such a treatment.

The roughening of the laminated surface 3 is achieved by forming the projections by the plating method as described above. The height of the projection is preferably made as uniform as possible. This is because if the protrusions are too high, it becomes difficult for the thermoplastic resin to flow into the concave portions, or it becomes difficult to form a fine pattern when forming a pattern by etching.
μm or less, and at most 50 μm or less are preferred. On the other hand, if the projections are too low, it will be difficult to obtain good adhesive strength. The shape of the projection is not particularly limited, but examples include a spherical shape, a needle shape, a conical shape, and a shape in which these are aggregated. If the density of the projections is too small, it is difficult to obtain sufficient adhesive strength. Therefore, 100 or more, preferably 500 or more per 1 mm ² is appropriate. Also, if the projections are too large, there is a risk that it becomes difficult to flow in the thermoplastic resin and a sufficient adhesive strength may not be obtained, so the projections are sandwiched between the surface of the conductive layer before the projections are formed and the tops of the projections. The volume of the protrusion in the space is preferably 80% or less, and more preferably 60% or less.

Next, a method of manufacturing a copper-clad laminate will be described with reference to FIGS. 2A, 2B, 2C, and 2D. First, a molding material made of a thermoplastic resin or the like is used. The plate-like molded body 1 is molded by extrusion molding, calender molding, injection molding, press molding or the like (see FIG. 2A). The molding material is prepared by mixing an additive, a filler, and the like with a predetermined thermoplastic resin serving as a base as necessary, and then compounding the mixture into pellets. In this case, since the thickness of the plate-shaped molded body 1 affects the accuracy of the thickness of the final product, it is preferable to finish the molding to a predetermined accuracy at the time of the molding. A well-known manufacturing method may be adopted for forming the plate-like molded body 1, and a high-precision plate can be formed relatively easily. Instead of molding the plate-shaped molded body 1, it is also possible to use a commercially available plate-shaped molded body 1.

Next, the entire laminated surfaces 3 of the pair of copper foils 2 are each subjected to a roughening treatment, and the laminated surfaces 3 of each of the treated copper foils 2 are directly superimposed on both flat surfaces of the plate-shaped molded body 1 (FIG. 2). (b)). At this time, in the case where the laminated surface 3 of the copper foil 2 is overlapped on one side of the plate-shaped molded body 1 instead of on both sides of the plate-shaped molded body 1, an appropriate separator or the like may be arranged on the non-overlapping surface. When the copper foils 2 are overlaid on both sides of the plate-like molded body 1 in this manner, these are sandwiched between a pair of stainless steel plates 4, and if necessary, a cushion material is overlaid on the outer surface of each stainless steel plate 4, and a heating device and a cooling device are provided. And pressurized and heated (Fig. 2
(See (c)).

The temperature at the time of setting is a temperature at which the thermoplastic resin of the plate-like molded body 1 does not flow at the time of initial pressurization. If this temperature is too low, it takes a long time to raise the temperature. Therefore, it is necessary to confirm in advance the temperature at which the pressure is reduced in the press device 5 and the material to be used, and set the temperature to be lower by about 1 to 50 ° C. than this temperature. Is good. Note that, depending on the heat capacity of the press device 5, even if the set temperature of the press device 5 is higher than the flow starting temperature, Since the temperatures of the copper foil 1 and the copper foil 2 do not reach the flow start temperature, it is possible to increase the set temperature.

If the pressure of the press device 5 is too high, the thermoplastic resin forming the plate-like molded body 1 flows rapidly, and it is extremely difficult to obtain a predetermined thickness and thickness accuracy. Conversely, if it is too low, poor adhesion between the thermoplastic resin and the copper foil 2 is likely to occur. Therefore, the pressure of the press device 5 depends on the viscosity of the thermoplastic resin to be used at the beginning of the flow, but is 1 kPa.
The pressure is selected from the range of Pa to 50 kPa. When the viscosity is high, the pressure is set high, and when the viscosity is low, the pressure is set low. The press device 5 is a hydraulic pressurization type,
It is desirable to use one equipped with a pressure gauge. This is because a decrease in pressure can be detected by maintaining the amount of oil sent during the initial pressurization.

When the plate-shaped molded body 1 and the copper foil 2 are pressurized at a predetermined pressure, the temperature is gradually increased at a predetermined speed. This is because if the heating rate is too fast, (1) the thermoplastic resin flows rapidly, and the time from the detection of the pressure drop to the cooling needs to be very short, making the control difficult. ) It is difficult to raise the temperature uniformly throughout. Therefore, it is preferable that the rate of temperature rise be 20 ° C./min or less. On the other hand, if it is too slow, it takes a long time to perform the operation. When the pressing device 5 is set to a high temperature, the temperature of the thermoplastic resin itself may be set to increase at the above-described speed. It is preferable that the hydraulic cock be closed during the temperature rise to maintain the amount of pressurized oil.

When the temperature rises, the pressure rises due to the thermal expansion of the thermoplastic resin. However, when the thermoplastic resin starts flowing slightly, the pressure starts to fall. Stop the flow of the plastic resin. Then, it is cooled to a predetermined temperature to strengthen the adhesion between the plate-shaped molded body 1 and the copper foil 2, and thereafter, these four outer peripheral edges are cut into a predetermined size and size, thereby manufacturing a copper-clad laminated substrate. (See FIG. 2D).

It is preferable that the time from the detection of the pressure drop to the start of cooling be as short as possible. Specifically, the pressure is set within approximately 30 seconds, and the pressure is reduced by 50% of the initial pressure.
It is desirable to keep this within%. This is because, when the thermoplastic resin is excessively flown, not only the predetermined thickness cannot be obtained, but also the adhesion between the plate-like molded body 1 and the copper foil 2 becomes insufficient and the adhesive strength is reduced, This is because air bubbles enter the surface.

According to the above, since the copper foil 2 is directly bonded to the plate-like molded body 1 molded with high precision, the reinforcing material 11 such as glass cloth which deteriorates the dielectric properties and the adhesive are omitted, and the substrate is used as a substrate. Can be significantly improved in dielectric properties.
Therefore, when used for an antenna, a high-frequency filter, or the like whose dielectric properties greatly affect the performance of a product, a printed wiring board with less noise can be easily provided. Further, since the flow of the thermoplastic resin is directly detected and stopped by the decrease in the press pressure, sufficient adhesion to the copper foil 2 can be greatly expected. Furthermore, since a fluid state with almost no change in thickness can be obtained, even when a crystalline thermoplastic resin is used, a copper-clad laminated board of a predetermined thickness and high accuracy can be obtained very easily. become.

In the above embodiment, the laminating surfaces 3 of the copper foil 2 are superposed and adhered on both sides of the plate-like molded body 1, but as shown in FIG. It is also possible to overlap the laminated surfaces 3 and bond them. Further, the forming of the plate-shaped formed body 1 and the roughening treatment of the lamination surface 3 of the copper foil 2 may be performed simultaneously or the order may be reversed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the copper-clad laminate and the method for manufacturing the same according to the present invention will be described together with comparative examples. Example First, a plate-like molded body 1 made of polyarylate was prepared,
A large number of protrusions are formed by plating on a laminated surface 3 of a pair of copper foils made of electrolytic copper foil to prepare a copper foil 2 which has been subjected to a surface roughening treatment (knobing process). Was superimposed on both sides of the plate-like molded body 1 respectively. As the plate-like molded body 1,
Thickness 2.0mm, thickness accuracy ± 0.05mm, dimension 310
mm x 310 mm unirate (manufactured by Unitika Ltd.,
(Product name) was used. The copper foil 2 has a thickness of 35 μm.
JTC (trade name, manufactured by Japan Energy Co., Ltd.) having a size of 310 mm × 310 mm was used.

When the copper foil 2 is overlaid on both sides of the plate-like molded body 1,
These were sandwiched between a pair of stainless steel plates 4 having a thickness of 1.5 mm, and were set in a hydraulic press device 5 provided with a heating device and a cooling device, and were heated under pressure. The press plate size of the press device 5 is 400 mm × 400 mm, and the diameter of the hydraulic cylinder is 220 mm. Also, the pressure is 1
The pressure was set to 4.7 MPa (substantial pressure for the material: 41.5 kPa), and the set temperature was set to 240 ° C. In addition, about the temperature condition, it tested by the same apparatus 5 beforehand. Under the conditions in this case, when the plate-shaped molded body 1 and the copper foil 2 are set and pressed at the set temperature of 200 ° C., the material temperature reaches the set temperature of 200 ° C. in one minute, and the pressurization is increased by 5 ° C./minute. When the temperature was raised in minutes, the temperature of the material also increased at this rate with little delay. The temperature at which the pressure was confirmed was 251 ° C.

While maintaining the oil amount at the time of pressurization, the strongly pressed plate-like molded body 1 and copper foil 2 are held at 240 ° C. for 1 minute,
When the temperature was raised in minutes, a decrease in the oil pressure was observed at 251 ° C., so that the cooling water of the cooling device was immediately supplied to start cooling. At this time, the pressure after drop is measured by a hydraulic gauge.
It was 5 MPa. And it cools to 120 degreeC as it is, the adhesion of the plate-shaped molded object 1 and the copper foil 2 is strengthened, these are removed from the press device 5, air-cooled at room temperature, and then cut on all sides to 300 mm x 300 mm. A copper-clad laminated substrate was obtained.

When the thickness of the copper-clad laminate thus manufactured was measured at 25 points at equal intervals, the average value was 2.92 mm, the maximum value was 2.96 mm, and the minimum value was 2.88 mm (including the copper foil 2).
No defective appearance was observed. When the 90 ° peel strength of the copper foil 2 was measured, it was 7.8 N / c.
m.

COMPARATIVE EXAMPLE Using the same material and apparatus as in the example, iron spacers having a thickness of 2.9 mm and a width of 20 mm were arranged around the plate-like molded body 1, and copper foil was placed on both sides of the plate-like molded body 1. After each of the two laminated surfaces 3 were stacked, they were set on a press device 5 set at 25 ° C. and heated under pressure. The pressure was set at 16.7 MPa (substantial pressure on the material: 41.5 kPa), and was set so as to be automatically maintained even if the value decreased.

Next, the plate-shaped compact 1 and the copper foil 2 are maintained at the above-mentioned temperature and pressure for 5 minutes, and cooled to 120 ° C. by supplying cooling water of a cooling device. Was removed from the press device 5 and air-cooled at room temperature, and then cut on all sides to obtain a 300 mm × 300 mm copper-clad laminated substrate.

The thickness of the produced copper-clad laminate is set to 2 at equal intervals.
When five points were measured, the average value was 2.97 mm and the maximum value was 3.97.
03mm, minimum value 2.91mm (including copper foil 2)
Although relatively good, it was confirmed that bubbles of about 3 mm were scattered between the plate-like molded body 1 and the copper foil 2.
When the 90 ° peel strength of the copper foil 2 was measured,
It was 9 N / cm.

[0031]

As described above, according to the present invention, there is an effect that the thickness and the thickness accuracy of the copper-clad laminated substrate can be ensured without generating bubbles by a relatively simple method. Also, excellent dielectric properties can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of a copper-clad laminate according to the present invention.

FIG. 2 is an explanatory view showing an embodiment of a method for manufacturing a copper-clad laminate according to the present invention, wherein FIG. 2 (a) shows a state where a plate-like molded body is molded, and FIG. The figure which shows the state in which the lamination surface of copper foil is superimposed on both surfaces of (a), the figure which shows the state which press-heats a plate-shaped molded object and a copper foil with a press device, (d) The figure of the board of a lamination state It is a figure which shows the state which cut the outer periphery of the shape-shaped molded object and the copper foil to predetermined size and size.

FIG. 3 is an explanatory sectional view showing another embodiment of the copper-clad laminated substrate according to the present invention.

FIG. 4 is a partial cross-sectional explanatory view showing a conventional copper-clad laminated substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plate-shaped molded object 2 Copper foil 3 Lamination surface 11 Reinforcement

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AB17B AB17C AB33B AB33C AK01A AK43A AT00A BA02 BA03 BA06 BA10B BA10C DD07B DD07C EH71 EJ17 EJ20 EJ42 EJ50 GB43 JB16A JG05 5E343 AA16 BB24 BB67 DD52 DD5239

Claims (2)

[Claims] 1. A copper-clad laminate substrate on which a copper foil is laminated on at least one side of a plate-like molded body made of a thermoplastic resin, wherein the copper foil laminated surface is subjected to a roughening treatment, A copper-clad laminated substrate, wherein the laminated surface of the copper foil is directly adhered to at least one surface without using an adhesive. 2. A laminating surface of a copper foil roughened on at least one surface of a plate-shaped molded body made of a thermoplastic resin, and the temperature of the plate-shaped molded body and the copper foil is lower than the flow temperature of the thermoplastic resin. A method for producing a copper-clad laminate, comprising applying a predetermined pressure at a low temperature, increasing the temperature at a predetermined speed, and cooling when the pressure is reduced, and bonding the plate-shaped compact and the copper foil. .