JP2000277917A - Multilayer printed wiring board and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new multilayer printed wiring board that assures high thermal conductivity, small thermal expansion coefficient and superior heat radiating property and low expansion property, and a method of manufacturing the same multilayer printed wiring board. SOLUTION: In this multilayer printed wiring board, a prepreg sheet 2, in which a heat resistant resin is impregnated into an alamide fiber paper and a copper foil 3, is provided on the surface is respectively provided to both surfaces of a copper clad ceramic plate 1, where an internal layer pattern is formed by adding boron to the alumina as the main element and then providing a thermosetting resin, and the through-holes 4, 5 are formed to the copper clad ceramic plate 1 and the prepreg sheet 2 and a thin copper layer is formed to these through-holes 4, 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board used for various electronic devices.

[0002]

2. Description of the Related Art In recent years, as typified by mobile phones, video cameras, personal computers, and the like, there has been a demand for higher performance, smaller size, thinner, and lighter weight of electronic devices. The LSI package is a conventional QFP (Qua)
d Flat Package), SOP (Small
Outline Package) from lead to B
GA (Ball Grid Array), CSP (C
(Hip Scale Package), and has progressed from conventional surface mounting to chip size mounting technology. As a result, printed wiring boards have increased the amount of heat generated from components due to the increase in mounting of chip components and higher densities, and have a large coefficient of thermal expansion, heat dissipation and heat resistance. Various problems have been raised regarding the reliability of boards after high-density mounting in high-performance and multifunctional electronic devices. On the other hand, in the conventional multilayer printed wiring board,
In addition to glass epoxy multilayer printed circuit boards and ceramic substrates, there are metal core substrates.

[0003]

However, in the conventional glass epoxy multilayer printed wiring board, a desired inner layer pattern is formed by etching a glass epoxy copper clad board by a subtraction method and then alternately with a glass epoxy prepreg sheet. It is manufactured by stacking, setting a copper foil on the front and back, performing lamination molding, drilling, through-hole copper plating, forming an exterior pattern, and the like. Such a multilayer printed wiring board has a glass transition temperature of 125 to 1 as a general property.
35 ° C, coefficient of thermal expansion 15-16 ppm in the XY direction, 50-60 ppm in the Z direction, thermal conductivity 0.2 W / MK, which is widely used in various fields. There was a problem that the mounting of power components and the reliability under a high temperature environment were not sufficient.

Conventionally, there is a ceramic substrate using a ceramic as an insulating layer in order to impart heat dissipation and low thermal expansion to a printed wiring board.
Since the drilling workability is extremely poor, it is necessary to drill a pilot hole larger than the through hole in the state of the green sheet before ceramic production and to fill the hole after firing, so that there is a problem that drilling cannot be performed. Further, a ceramic multilayer printed wiring board made of a synthetic resin of a prepreg sheet has a problem in that the ceramic has a low coefficient of thermal expansion, and is easily peeled off due to a difference in thermal expansion of the ceramic during a solder heat resistance test and a heat cycle test.

Further, conventionally, in order to mount power components and improve heat dissipation, a metal core multilayer board using an aluminum / copper plate is prepared by drilling a pilot hole larger than a through hole in a metal in advance by drilling or pressing. , Metal surface treatment,
It is manufactured by filling a hole with a prepreg for drilling, a resin sheet or copper foil, forming an inner layer pattern by a subtraction method, alternately arranging and laminating the prepreg sheet, forming a hole, forming a through-hole copper plating, and forming an outer layer pattern. Therefore, the metal core multilayer board has high reliability after mounting on the insertion component and can be expected to have a heat radiation effect. However, there are the following problems in the reliability after mounting on the surface mounting component QFP mounting product and the like. . That is, the metal core substrate
Compared to glass epoxy multilayer printed wiring boards, the elastic modulus is extremely large, the thermal conductivity is good and the heat dissipation is excellent, but the substrate temperature rises and falls rapidly during the heat cycle, so the difference between the elastic modulus and the substrate temperature And the solder joints of the surface mount components are stressed, cracks are likely to occur between the pads on the board and the solder or between the mount components and the solder, causing breakage as the heat cycle test progresses, etc. There were also issues related to reliability.

As described above, the conventional glass epoxy multilayer printed wiring board has a heat radiation property, heat resistance, thermal expansion property and the like of the board, and the ceramic multilayer board has a workability and peeling due to a difference in thermal expansion coefficient from the prepreg sheet. In addition, the metal core multilayer board has a problem in that thermal stress is applied to the solder joint between the substrate of the surface mount component and the solder joint, and cracks easily occur. Then, this invention was made in order to solve such a subject, and has high heat conductivity,
It is an object of the present invention to provide a novel multilayer printed wiring board having a small thermal expansion coefficient and excellent heat dissipation and low expansion properties, and a method for manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a multilayer printed wiring board comprising a copper-clad ceramic board having an inner layer pattern formed by adding boron to alumina as a main component and interposing a thermosetting resin. And, a prepreg sheet provided on both sides of this copper-clad ceramic plate and impregnated with heat-resistant resin in aramid fiber paper and provided with a copper foil on the surface thereof, and a through-hole in the copper-clad ceramic plate and the prepreg sheet. And a thin copper layer formed in the through hole.

A multilayer printed wiring board according to a second aspect of the present invention is the multi-layer printed wiring board according to the first aspect, wherein a metal core is embedded in the prepreg sheet.

According to a third aspect of the present invention, there is provided a multilayer printed wiring board comprising: a copper-clad ceramic plate in which boron is added to alumina as a main component and an inner layer pattern is formed by interposing a thermosetting resin; 2. A printed wiring board having a prepreg sheet having a prepreg sheet provided on both sides of a board and impregnated with a heat-resistant resin in aramid fiber paper and having a copper foil on the surface thereof, is laminated in a plurality of stages. belongs to.

The multilayer printed wiring board according to claim 4 of the present invention is characterized in that the contact surface of the prepreg sheet of the copper foil is rougher than the surface on the opposite side. It is described in any of them.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, wherein boron is added to alumina as a main component, and an inner layer pattern is formed on a copper-clad ceramic plate with a thermosetting resin interposed therebetween. And a second step of superimposing a prepreg sheet impregnated with a heat-resistant resin on aramid fiber paper on both surfaces of the copper-clad ceramic plate, respectively.
A third step of pressure-forming a copper foil on each of the prepreg sheets, and forming a through-hole in the copper-clad ceramic plate, the prepreg sheet and the copper foil, and forming a copper plating layer in the through-hole. Step 4, and after that, the same prepreg sheet as the prepreg sheet is further superimposed on each of the prepreg sheets via the copper foil to perform pressure molding, and the predetermined copper foil provided on the surface of the prepreg sheet is formed. The method includes a fifth step of removing a portion by etching, and a sixth step of forming a through hole in the predetermined portion and forming a copper plating layer in the through hole.

[0012]

Embodiment 1 Hereinafter, Embodiment 1 of the present invention will be described.
1 will be described with reference to FIG. FIG. 1 is a sectional configuration diagram of the multilayer printed wiring board according to the first embodiment. In FIG. 1, reference numeral 1 denotes a double-sided copper-clad ceramic insulating plate.
Is added, and drilling machining is enabled through what is generally called a thermosetting resin, and an inner layer pattern is formed by a subtractive method. This double-sided copper-clad ceramic insulating plate 1 has a thermal conductivity of 18
It has flexibility by adding boron with W / mK alumina as a main component.

Reference numeral 2 denotes a prepreg sheet which is superposed on both sides of a double-sided copper-clad ceramic insulating plate. Aramid fiber paper (manufactured by DuPont) as a reinforcing fiber is impregnated with a heat-resistant epoxy resin and dried at 130 ° C. for 10 minutes. Things. Aramid fiber paper is used as the prepreg sheet 2 because it has a small coefficient of thermal expansion and a small difference in coefficient of thermal expansion with the ceramic at the bonding interface with the ceramic. This is because it is hard to occur. Further, since the prepreg sheet 2 is impregnated with a heat-resistant epoxy resin to form a composite material with ceramic, cracks and cracks due to warpage and the like are reinforced and vibration resistance is improved. The thickness of the prepreg sheet 2 is 0.05 mm to 0.1 mm. For example, when the thickness of the prepreg sheet 2 is 0.05 mm or less, the withstand voltage and the moisture resistance decrease, which is not preferable.
If it is not less than mm, microvoids remain during the lamination molding, which is not preferable because the thermal conductivity of the prepreg sheet 2 decreases and the coefficient of thermal expansion increases. The prepreg sheet 2 is brought into close contact with the double-sided copper-clad ceramic insulating plate 1, but since the copper foil of the double-sided copper-clad ceramic insulating plate 1 has a roughened surface to be brought into close contact with the ceramic, the copper foil is removed by etching. When the circuit of the inner layer is formed, the roughened surface of the copper foil remains on the ceramic to improve the adhesion of the prepreg sheets 2 and 2. Also,
With the configuration of the double-sided copper-clad ceramic insulating plate 1 and the prepreg sheet 2 in which aramid fiber paper is impregnated with a heat-resistant epoxy resin, the thermal expansion coefficient becomes smaller than when only the aramid prepreg sheet is used. Due to the reduced expansion, the reliability of the solder joint after mounting the surface mount component is also improved.

Reference numeral 3 denotes a copper foil formed by roughening one surface of the prepreg sheets 2 and 2 so that the rough surface is in contact with the prepreg sheets 2 and 2. It was molded under pressure at a temperature of 180 ° C. for 90 minutes. Thus, the prepreg sheet 2 impregnated with heat-resistant epoxy resin on aramid fiber paper is bonded to the double-sided copper-clad ceramic insulating plate 1 to improve the resistance to cracks and cracks against external mechanical stress.

Here, a hole for forming a through-hole is formed by using an NC drill machine, and a copper plating layer is formed by applying a through-hole copper plating. Next, the above-mentioned prepreg sheets 2 and 2 are laminated on these copper foils 3 and 3, and the copper foils 3 and 3 each having a roughened surface are superimposed thereon, and a pressure of 30 kg is applied using a vacuum press. / Square cm, temperature 180 ° C., pressure and heat molding for 90 minutes to form a laminated core material. Drill film holes are made in this laminated core material, a dry film is laminated, and a mask film provided with a plus relief in the diameter of the non-through through hole 4 is set on the front and back of the laminated core material, and exposed, developed, and etched. The copper foil 3 corresponding to the non-through hole 4 is removed in advance. Next, a through-hole 5 penetrating the double-sided copper-clad ceramic insulating plate 1 is drilled using an NC drill, and the aramid fiber is a polymer fiber. Drill the through-hole 4. When drilling a via with a carbon dioxide gas laser, the copper foil is etched in advance by providing a relief with a diameter larger than the desired via diameter. Therefore, it is possible to effectively prevent the adhesiveness of the residual copper foil around the vias from being reduced by the laser, and since the hole shape of the vias by the laser becomes a mortar shape, the reliability of the plated roundness and the reliability of the non-penetrating through holes are also improved. Significantly improved. Next, the remaining film is treated with permanganic acid and plated with through-hole copper.
Finally, a circuit is formed by a normal subtraction method to form a multilayer printed wiring board. In this way, the through-holes 5 are formed in the double-sided copper-clad ceramic insulating plate 1 to improve heat dissipation. In addition, through through hole 5
During the formation of the film, a film is stuck so as not to cause cracks and cracks in the ceramic.

[0016]

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. In the second embodiment, two double-sided copper-clad ceramic insulating plates 1 similar to the first embodiment are used, and a prepreg sheet 2 made of similar aramid fiber paper is interposed between the two, and they are superposed. The prepreg sheets 2 and 2 are further superimposed on the copper-clad ceramic insulating plates 1 and 1 respectively. On each of these prepreg sheets 2 and 2, a copper foil whose one surface is roughened to, for example, 18 μm is overlapped and pressed by a vacuum press.
The laminate is formed by heating. A through-hole 4 is formed in this laminated molded product by an NC drill, and a desmear process and a through-hole plating process using plasma are performed, and a circuit is formed by a normal subtraction method. The reason why plasma is used as the desmear processing when the through-hole 4 is formed by the NC drill is that the desmear processing can be performed simultaneously.

Next, a prepreg sheet 2 is further superimposed on the front and back surfaces, a copper foil roughened to, for example, 12 μm is superposed on each of them, and lamination molding is performed by vacuum press. A film alignment hole is provided in this molded product, a dry film is laminated, and exposure, development, and copper foil etching are performed using a mask film provided with a relief of the diameter of the non-through hole. Then N
A through-hole 5 is provided by a C drill, and a non-through-hole 4 is formed by a carbon dioxide laser device. Thereafter, a multilayer printed wiring board as shown in FIG. 2 is completed in the same manner as described in the first embodiment. In addition, even when the via of the non-penetrating through hole 4 is formed by the laser on the prepreg sheet 2 made of aramid fiber paper, the plasma treatment is used for the remaining film treatment. As described above, according to the second embodiment, the use of the two double-sided copper-clad ceramic insulating plates as shown in FIG. Since the target configuration is obtained when the basic configuration is performed, warpage and twist can be reduced.
Further, even in the case of a high multilayer structure, since the through-holes 5 are formed directly on the double-sided copper-clad ceramic insulating plate, heat can be radiated through the through-holes 5.

[0018]

Third Embodiment A third embodiment of the present invention relates to a multilayer printed wiring board using a metal core, which will be described with reference to FIG. FIG. 3 is a sectional configuration diagram of the multilayer printed wiring board according to the third embodiment. In the figure, 6
Is a metal core using, for example, aluminum, and a hole having a diameter of about 1 mm larger than the diameter of the through hole is previously formed by an NC drill. A prepreg sheet 2 impregnated with a heat-resistant resin is stacked on both sides of the metal core 6, and a copper foil roughened to one side of, for example, 18 μm is stacked on the prepreg sheet 2. Perform molding 2
A layer metal core copper clad plate is formed. This two-layer metal-core copper-clad
A through-hole is formed by a C drill, and a permanganate treatment is performed to improve the adhesion with the through-hole. After that, through-hole copper plating is applied,
A circuit is formed by a normal subtraction method to form a two-layer metal core substrate. The prepreg sheet 2 is placed on the front and back of the two-layer metal core substrate, and the double-sided copper-clad ceramic insulating plate 1 described in the first embodiment is placed thereon. Further, the prepreg sheet 2 and the copper foil 3 are respectively laminated on the double-sided copper-clad ceramic insulating plate 1 and laminated and formed under predetermined conditions. Subsequent steps are performed in the same manner as described in the first embodiment to complete a multilayer printed wiring board as shown in FIG. According to the third embodiment, by bonding the prepreg sheet 2 and the double-sided copper-clad ceramic insulating plate to the front and back sides of the metal core substrate, it is possible to realize a low thermal expansion of the metal core substrate, thereby stabilizing the dimensions. In addition to using a metal core substrate, it becomes possible to mount surface mount components such as QFP. Further, with the lower thermal expansion, the reliability of the through-hole conduction resistance during the heat cycle test is also improved.

[0019]

Fourth Embodiment A fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional configuration diagram of a multilayer printed wiring board in which two two-layer metal core substrates described in the third embodiment are used, and the front and back sides of the multilayer printed wiring board are formed by the same steps as those described in the third embodiment. . Embodiment 4
Since two metal cores 6 are used and a composite structure of a double-sided stretched ceramic insulating plate and a prepreg sheet 2 is used on them, it is possible to expect a large heat dissipation. The reliability at the solder joint is further improved.

[0020]

As described above, according to the present invention, since boron is added to alumina as a main component and a thermosetting resin is interposed, drilling machining becomes possible, and heat dissipation is improved.
In addition, the thermal expansion coefficient is reduced by the structure of the copper-clad ceramic insulating plate and the prepreg sheet impregnated with heat-resistant resin in aramid fiber paper, and the reliability after mounting surface-mounted components is improved. Since the interface separation with the ceramic hardly occurs and the composite material with the ceramic is formed, there is an effect that reinforcement against cracks and cracks due to warpage or the like can be performed.

[0021]

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a multilayer printed wiring board according to the present invention.

FIG. 2 is a sectional configuration diagram of a multilayer printed wiring board according to the present invention.

FIG. 3 is a cross-sectional configuration diagram of a multilayer printed wiring board according to the present invention.

FIG. 4 is a sectional configuration view of a multilayer printed wiring board according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Double-sided copper-clad ceramic insulation board ... Low thermal expansion prepreg sheet 3 ... Copper foil 4 ... Non-through through hole 5 ... Through through hole 6 ... Metal core

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideaki Arai 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. F-term (reference) 5E343 AA02 AA13 BB24 BB67 DD80 GG04 5E346 AA02 AA06 AA12 AA15 AA22 AA25 AA42 AA43 BB01 CC05 CC08 CC17 CC32 DD02 DD12 DD32 EE02 EE06 EE07 EE09 EE13 EE19 EE31 FF07 GG15 GG17 GG28 HH11 HH17

Claims (5)

[Claims] 1. A copper-clad ceramic plate in which boron is added to alumina as a main component and an inner layer pattern is formed with a thermosetting resin interposed, and provided on both surfaces of the copper-clad ceramic plate, respectively. A prepreg sheet impregnated with a heat-resistant resin and provided with a copper foil on its surface, a through-hole formed in the copper-clad ceramic plate and the prepreg sheet, and a thin copper layer formed in the through-hole. A multilayer printed wiring board characterized by the following. 2. The multilayer printed wiring board according to claim 1, wherein a metal core is embedded in the prepreg sheet. 3. A copper-clad ceramic plate in which boron is added to alumina as a main component and a thermosetting resin is interposed to form an inner layer pattern, and provided on both surfaces of the copper-clad ceramic plate, respectively. The multilayer printed wiring board according to claim 1, wherein a plurality of printed wiring boards each including a prepreg sheet having a copper foil provided on a surface thereof impregnated with a heat-resistant resin are laminated. 4. The multilayer printed wiring board according to claim 1, wherein a contact surface of the copper foil with the prepreg sheet is rougher than a surface opposite to the prepreg sheet. 5. A first step of forming an inner layer pattern on a copper-clad ceramic plate in which boron is added to alumina as a main component and a thermosetting resin is interposed, and an aramid fiber paper is impregnated with a heat-resistant resin. A second step of superimposing a prepreg sheet on both sides of the copper-clad ceramic plate, a third step of pressure-forming a copper foil on each of the prepreg sheets, and the copper-clad ceramic plate, the prepreg sheet, and the A fourth step of forming a through hole in the copper foil and forming a copper plating layer in the through hole, and thereafter, further superimposing the same prepreg sheet as the prepreg sheet on the prepreg sheet via the copper foil. A fifth step of removing a predetermined portion of the copper foil provided on the surface of the prepreg sheet by etching, and forming a through-hole on the predetermined portion. And forming a copper plating layer in the through-holes of the multilayer printed wiring board.