JPH11204906A - Manufacturing method for resin compound ceramics printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a through hole of a metal foil applying compound ceramics board from generating a copper foil burr and a small blade breakage, by machining a drill hole having a less specific value of a convex and concave surface without substantial warping. SOLUTION: A metal foil for a metal foil applying resin compound ceramics board is used for a pressurized and extended copper foil having a copper foil of which processing surface for adhesion has a less low profile processing of a recessed and protruded surface or an electrolytic copper foil having a pressurized and extended specification. A protecting coating is applied on the copper foil surface and the protecting coating is used for an applied film by an adhesive tape of a cellulose group or an applying agent of an acrylic or cellulose group by drill hole machining. The recessed and protruded surface by a section observing for a through hole wall is less than 2 μm and a 'direct plating' copper plating using palladium colloid or palladium-tin colloid is preferable for a through hole plating. By the means a heat radiation, a low thermal expansion ratio and a heat-resistance are superior and specifications as a printed board can not be obstructed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board with through-hole plating using a metal foil-clad resin composite ceramics plate, and more particularly, to a high frequency using a metal foil-clad nitride-based resin composite ceramics plate. It can be suitably used for applications.

[0002]

2. Description of the Related Art A method for manufacturing a ceramic wiring board includes:
Various methods have been developed and put into practical use. These include a ceramic wiring board using a thick film method, a ceramic wiring board using a thin film method, a ceramic wiring board using a green sheet method, a ceramic wiring board using a plating method, and a ceramic wiring board using an etching method. Except for the manufacturing method of the etching method ceramic wiring board, these ceramic wiring boards do not use a copper-clad board pre-coated with copper foil, a method of sintering the conductor simultaneously with the ceramic, a method of printing and sintering, It was formed by an evaporation method such as sputtering or plating.

[0003] An etching ceramic wiring board is typically manufactured by eutectic press bonding of a copper foil having a thickness of about 150 μm to an aluminum nitride substrate via an oxide layer. No workability was found, and the workability was the same as that of ordinary ceramics, and was extremely expensive.

[0004] Cordierite is selected as an inorganic continuous pore sintered body, a thin glass cloth disposed on the surface is impregnated with a resin, and a copper foil is stretched on both sides thereof. In this case, drilling is possible, but it is difficult to use a normal steel drill or the like.In addition, since the surface of the ceramic has the same layer as the conventional glass-epoxy laminate, its physical properties are Had significant restrictions.

Further, as a ceramic-resin composite copper-clad substrate, there is a substrate obtained by kneading a fine powder of alumina, silica or the like into a fluororesin or the like, forming a plate shape, and attaching copper foils to both surfaces thereof. However, this substrate is a substrate in which ceramic powder is dispersed in a resin. Basically, it is a ceramic-containing resin substrate, and its physical properties largely depend on the resin component. , High thermal conductivity cannot be achieved.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been devoted to the manufacture of printed wiring boards having high dimensional accuracy by utilizing the excellent properties of ceramics such as low coefficient of thermal expansion, high heat dissipation and heat resistance. As a result of the examination, after applying a thermosetting resin to the inorganic continuous pore sintered body and curing it to form a resin composite ceramic, a method of slicing it into a thin plate shape was applied for a patent (JP-A-5-291706, JP-A-61-252086). , USP-5,531,945,
EP-0,566,360 etc.) Furthermore, as a result of intensive examination,
A novel metal-foil-clad composite ceramics plate in which the metal foil is firmly adhered directly via a minimal adhesive layer by simultaneously performing the bonding of the metal foil and the production of the resin composite ceramics layer has been discovered (Japanese Patent Application Laid-Open No. -295581, 08-244163, etc.)
.

In the process of practical use, a metal foil-clad nitride-based resin composite ceramic plate using a nitride such as aluminum nitride as a ceramic layer is used to manufacture a printed wiring board with through-hole plating according to the subtractive method. We studied the law diligently. As a result, in order to obtain a good product, the shape of the drill hole, surface irregularities, prevention of copper foil burrs at the entrance and exit of the hole, prevention of chipping when drilling, etc. are extremely important. It was also found that selection was necessary, and based on this, the present invention was completed.

[0008]

That is, the present invention relates to a method for manufacturing a printed wiring board with through-hole plating using a metal foil-clad resin composite ceramic plate, wherein the through-hole has substantially no bending. This is a method for producing a resin composite ceramics printed wiring board with through-hole plating, characterized by drilling holes having a surface irregularity of 5 μm or less by cross-sectional observation.

In the present invention, the metal foil-clad resin composite ceramics plate is a metal foil-clad nitride-based resin composite ceramics plate, and the metal foil of the metal foil-clad resin composite ceramics plate has a low bonding surface. Profile processing and below (10
A copper foil rolled copper foil or a rolled electrolytic copper foil having a surface roughness of about 5 μm or less (point average surface roughness Rz is about 5 μm or less), which is to be subjected to a protective coating on the copper foil surface and drilled. The protective coat is a cellulose-based pressure-sensitive adhesive tape or a coating film of a cellulose-based or acrylic resin-based paint, the surface roughness of the through-hole hole wall is 2 μm or less, and the through-hole plating is palladium. A direct plating copper plating using a colloid or a palladium-tin colloid is a more preferable method for producing a resin composite ceramics printed wiring board.

According to the production method of the present invention, the excellent properties of the metal-foil-clad resin composite ceramic plate, especially the high heat dissipation properties of the metal-foil-clad nitride resin composite ceramic plate,
In addition to a low coefficient of thermal expansion, heat resistance, and excellent electrical properties, a printed board can be utilized to the fullest extent without harming these properties. In addition, the present invention is naturally applicable to a multilayer board having three or more layers, and for example, can be used as a high-frequency multilayer board having a microstrip line formed in an inner layer.

Hereinafter, the configuration of the present invention will be described. The metal-foil-clad resin composite ceramic plate of the present invention is obtained by impregnating a thermosetting resin into an inorganic continuous porous sintered body and laminating and bonding a metal foil to one or both surfaces thereof. As an inorganic continuous pore sintered body, aluminum nitride-boron nitride composite (AlN-h-BN) and alumina-boron nitride composite (Al ₂ O ₃ -hB)
N), zirconium oxide-aluminum nitride-boron nitride-
Nitride-based materials such as boron nitride composite (Zr-h-BN-AlN),
Preferable are wollastonite such as β-wollastonite (β-CaSiO ₃ ), and in addition, cordierite (2MgO / 2Al ₂ O ₃ / 5SiO ₂ ), mica and the like.

Examples of the thermosetting resin include an epoxy resin, an unsaturated polyester resin, a diallyl phthalate resin, an acrylic resin, a cyanate resin (cyanate resin, cyanate-epoxy resin, cyanate-maleimide resin, cyanate-ester). Maleimide-epoxy resin), maleimide resin, maleimide-vinyl resin, bisallylnadiimide resin, other thermosetting resins, and a composition obtained by appropriately mixing two or more of them. Particularly, in the present invention, as the thermosetting resin, a resin obtained by blending an epoxy resin from an aromatic hydrocarbon-formaldehyde resin novolak with a cyanate resin is preferable.

Examples of the metal foil include an electrolytic copper foil, a rolled copper foil, a rolled electrolytic copper foil, a copper foil for a lithium battery, an aluminum foil, a nickel foil, a nickel-plated copper foil, and a nickel-plated copper foil with an adhesive layer. . The surface roughness of the treated surface for bonding is low profile treatment or less, Ra about 0.2μm
Hereinafter, those having a 10-point average surface roughness Rz of surface roughness of about 5 μm or less are preferred, and rolled copper foil, rolled copper foil, copper foil for lithium batteries and the like are particularly preferred.

Using the above-mentioned metal foil-clad resin composite ceramic plate, a printed wiring board with through-hole plating according to the present invention is manufactured according to the most common substrate method for a glass-epoxy copper-clad laminate. In the present invention,
As a through-hole, there is substantially no bend, and the surface unevenness by cross-sectional observation is 5 μm or less, more preferably 2 μm.
m or less.

[0015] The curvature of the holes and the surface irregularities are particularly important when used for high-frequency components and the like. Bending significantly impairs positional accuracy. For example, it may lead to deterioration of shield performance in the case of through-hole shield, etc.
This hinders the positional accuracy of the wiring interval. Therefore, it is preferable to secure a high position accuracy equal to or higher than the absolute position accuracy required for the printed wiring pattern. Further, if the surface irregularities of the hole wall are large, the high-frequency loss is increased, which is not preferable. Therefore, it is preferable to make the surface of the copper foil closer to the surface unevenness or to secure higher smoothness.

In addition, if there is a bend in the cross section of the hole after the through-hole plating by microscopic observation or if the surface has large irregularities, the drill hole is drilled even if it appears that good through-hole plating has been performed. Occasionally, fine cracks and the like are often generated, and the cracks may be developed by a thermal cycle test or the like, and may be partially peeled off of the ceramic-resin composite layer. From these points, it is more preferable to use a drilled hole having substantially no bend and having a surface unevenness of 2 μm or less, particularly by cross-sectional observation.

In the case of the conventional glass epoxy laminate, the adhesion strength of the through-hole plated metal is considered to be a problem.
If this value is not large, a crack may occur in the copper plating of the through-hole due to a thermal cycle or the like, and the through-hole may be broken. For this reason, it is preferable that the drill hole wall surface has some irregularities. Further, in the case of a ceramic substrate of a plating method in which a metal layer such as copper is formed on the ceramic substrate by a plating method, surface irregularities are imparted by etching in order to ensure adhesion. However, in the case of the present invention, since this is not a resin matrix or ceramics but a resin composite ceramics layer, this problem has been solved. That is, from the relation of the coefficient of thermal expansion, an excessive tensile stress is not applied to the through-hole metal in the high-temperature assembling process as in the case of the glass epoxy laminate, but rather a compressive stress. In addition, unlike ceramics, even if it is smooth, it is possible to ensure adhesion that sufficiently withstands heat cycles.

In the drilling, the rotation speed of the drill is selected from a range of a peripheral speed of the drill of 1 m / sec or less, preferably from 0.3 to 0.6 m / sec. This is 0.8 ~
For a 0.3mmφ drill, the range is 5,000 to 30,000 rpm. In addition, according to the selected rotation speed of the drill, a drill in which the optimum feed speed of the drill, the type of the cutting edge of the drill and the type of the discharge groove, etc. are commercially available, and it is preferable to select this. In addition, when using the drill for normal glass epoxy copper clad laminate, these are 0.8-0.
50,000-120,000 rp for 3 mmφ drills
m., so the feed rate is greatly reduced.

In the case of the resin composite ceramics plate of the present invention,
Since the specific gravity of the facet powder generated by drilling is mainly composed of ceramics, it is as large as about twice or more that of a conventional glass epoxy laminated board or the like, hard, and contains resin. If the facets are not sufficiently discharged, the drill rapidly wears out, and good drilling cannot be performed. Therefore, it is preferable to select the drill in consideration of the ejection of the facets in addition to the hardness. As a drill for drilling, a hard or ultra-hard drill often used for a glass epoxy laminate can be used, but in order to increase abrasion resistance, a thin film is formed using titanium nitride or titanium carbide. Drills coated in multiple layers and CVD diamond coated drills can be used more suitably. Of course, a diamond tip drill with a diamond tip at the tip can also be used.

In the drilling, the ceramic plate is liable to be chipped when drilling. Edge chipping and surface unevenness of the drill hole wall decrease as the rotation speed is increased. In the case of a small-diameter drill, the damage is also reduced by increasing the rotation speed. However, when the number of rotations is increased, the hole position accuracy is reduced, and the copper burrs (copper burrs) at the holes are also increased. Further, although the occurrence of copper foil burrs decreases due to a decrease in the rotation speed and an increase in the cutting speed, the clogging of the cutting powder and the abrasion of the drill are increased, and in particular, a small diameter drill is easily broken. In addition, drills with a diameter of 0.6 mm or less are likely to break if the drill material is extremely hardened, and the problem that the broken tip tends to remain in the unpenetrated hole tends to occur. It becomes remarkable.

As described above, in drilling, it is not easy to find good conditions by selecting the conditions. Therefore, in the drilling described above, in the present invention, a protective coat is applied to the copper foil surface of the metal foil-clad resin composite ceramics plate, in particular, a coating film made of a cellulose-based adhesive tape or a cellulose-based or acrylic resin-based paint. It is preferable to use those that have been subjected to the treatment. Conventionally, there are adhesives (such as shellac) which are conventionally used for fixing a work for processing a ceramic plate (including wafers), and a film which is hardened by heat or ultraviolet irradiation and becomes peelable. Although it is conceivable to use these for a protective coat, they are less effective in preventing the occurrence of copper foil burrs.

As the cellulosic adhesive tape, a thin and more pure cellulosic film is used.
(Without various modifications) is more preferable. As the cellulose-based or acrylic-based paint, lacquers used as woodwork finishes are preferably mentioned. In addition to nitrocellulose, methylcellulose, ethylcellulose, acetylcellulose, ethylhydroxyethylcellulose, carboxymethylethylcellulose and the like can be used as cellulose. Nitrocellulose is low nitrogen nitrate (N
0.7% or less) is preferable for safety. In addition, an acrylic resin is used as a component of the paint, and in addition, an alkyd resin, a styrene resin, a styrene-butadiene resin, an unsaturated polyester resin, and the like can be used as appropriate.

By using the metal-foil-clad resin composite ceramics plate provided with the above-mentioned protective coating, good drilling with excellent hole position accuracy and no hole chipping or copper foil burrs can be easily performed by selecting drill conditions. Is achieved. Note that when a copper foil burr "burr" projecting about several microns from the copper foil surface at both ends of the hole is formed, through-hole plating can be performed as it is. However, it is preferable to remove the burr and soft etching is performed.

In addition, an entry boat such as an aluminum sheet or a press board which is generally used for drilling a conventional glass epoxy copper clad laminate can be used.
It has little effect on the above-mentioned good drilling. Naturally, a backup board such as a paper phenol laminate or a melamine board can be used. Drilling is usually a method in which the drill descends vertically. However, there are also drills of the type using horizontal movement or vertical ascending, and in these cases, the above-mentioned cutting pieces are easily discharged, and the drilling property is further improved.

Next, in the present invention, through-hole plating is performed on the metal foil-clad resin composite ceramic plate that has been subjected to the hole processing. As a plating method, any method can be used as long as conditions are selected, using a method used for a conventional glass epoxy copper-clad laminate, but in the present invention, in particular, a direct plating method using a palladium colloid or a palladium-tin colloid is used. Copper plating is preferred, and the STS method is particularly preferred.

Direct plating copper plating using a palladium colloid or a palladium-tin colloid is performed by depositing fine particles of palladium or palladium-tin on the surface to make them electrically conductive and then performing electroplating. In the STS method, inorganic polyhydric acids (sulfuric acid, phosphoric acid, etc.), formalin and vanillin having the function of an emulsifier are used instead of sodium chloride and hydrochloric acid as components for preparing a colloid solution for precipitating fine particles of palladium or palladium-tin. It is characterized in that it is used.

In the present invention, using the double-sided copper-clad substrate with through-hole plating obtained above, attaching a resist, exposing,
The printed wiring board is developed and etched. In the method, in particular, in the case of a metal foil-clad resin composite ceramics plate using a rolled copper foil, since the etching rate of the plated copper and the rolled copper foil is different, in consideration of that point, a finer Realize etching.

[0028]

The present invention will be described below with reference to examples. Example 1 A metal foil-clad resin composite ceramic plate having a thickness of 1
A copper-clad composite aluminum nitride sheet of 0.64 mm thick and 125 mm x 125 mm covered with a rolled specification rolled copper foil with a low profile of 8 µm was used. As the copper-clad composite aluminum nitride plate,
Untreated (no), a commercially available lacquer was applied to both surfaces of the copper foil and dried to form a glossy transparent coating (lacquer), and a cellophane-tacky adhesive (tape) was prepared.

Using NEO-120 manufactured by Rokuro Sangyo Co., Ltd., the drilling conditions were changed as shown in Table 1 and drilling was performed. For NC control, a FUNAC small diameter deep hole drilling cycle (G83) was used. A 2mm thick melamine board was used as a backup board, and a 0.4mm thick aluminum sheet was used as an entry board. The hard drill bit is a miniature drill for printed circuit boards 0.35MX (0.35mm diameter), MS060 (0.6mm diameter) manufactured by Mitsubishi Materials Corporation.
Diameter) was used.

Among the drilled products, lacquer coated products,
For cellophane tape products, these were peeled off and both sides were cleaned. The perforated plate was plated through-hole with a thickness of 10 μm by direct plating using a palladium colloid method.

A photoresist is attached to both sides, exposed, developed, and etched to form a desired printed wiring.
Further, the surface is electroless plated with 1 μm nickel,
A μm electroless gold plating was applied. About the obtained printed wiring board with a through-hole plating, the cross-section of the through-hole was observed with a microscope and other physical properties were tested.
The results are shown in Table 1.

The physical properties in Table 1 were evaluated as follows. * 1: 20 drill holes are arbitrarily selected and evaluated based on the displacement of the upper and lower ends of the holes. * 2: The maximum value of the protruding height of the copper foil from the upper and lower surfaces of the drill hole. * 3: The maximum value of the unevenness is obtained by sealing the through-hole plating hole with resin, cutting it, and taking a cross-sectional micrograph. * 4: Place the printed wiring board on a hot plate at a temperature of 200 ° C and solder with a soldering iron. Thereafter, the solder and copper are removed by etching, and after drying, they are immersed in a methyl ethyl ketone solution containing a dye, and the presence or absence of cracks around the holes is observed. * 5: 30 minutes at room temperature → 30 minutes at 150 ° C → 30 minutes at room temperature → 30 minutes at -40 ° C →
With room temperature as one cycle, observe the state of through-hole plating after the cycle. ：: good without cracks, △: slightly cracked, ×:
Cracked

[0033]

[Table 1] Types of protective coat Lacquer ← ← No tape Lacquer No drill diameter (mm) 0.35 ← ← ← ← 0.6 ← Number of rotations (× 10 ³ rpm) 11 23 40 23 ← 18 ← Feed speed (mm / min) 25 ← ← ← ← 50 ← Each cutting depth (mm) 0.1 ← ← ← ← 0.5 ← Drill hole position accuracy (μm) ^{* 1} 3 4 21 5 5 2 4 Copper foil burr height (μm) ^{* 2} 3 2 24 2 27 2 23 Hole cross section wall surface unevenness (μm) ^{* 3} 13 2 2 3 18 3 14 Solderability (with or without cracks) ^{* 4} Yes No No No Yes No No Appearance after no heat cycle ^{* 5} △ ○ ○ ○ × ○ ×

[0034]

As described above, according to the production method of the present invention, the excellent characteristics of the metal-foil-clad resin composite ceramic plate, particularly the high heat dissipation and the low coefficient of thermal expansion of the metal-foil-clad nitride-based resin composite ceramic plate In addition to heat resistance and excellent electrical properties,
As a printed board, without harming these characteristics,
You can make the most of it. Therefore, high-frequency (millimeter-wave) antennas, high-frequency part modules, other substrates and substrates for direct mounting of semiconductor chips (for example,
It can be suitably used as a through hole for conduction such as a chip-sized package substrate) and as a through hole shield.

Claims (6)

[Claims] 1. A method for producing a printed wiring board with plated through holes using a metal foil-clad resin composite ceramics plate, wherein the through holes have substantially no bending,
A method of manufacturing a resin composite ceramic printed wiring board with through-hole plating, characterized by drilling a surface having a surface unevenness of 5 μm or less by cross-sectional observation. 2. The metal foil of the metal foil-clad resin composite ceramic plate is a copper foil rolled copper foil or a rolled electrolytic copper foil whose surface for bonding has a surface unevenness of low profile treatment or less. The method for producing a resin composite ceramics printed wiring board according to claim 1, wherein a protective coat is applied to the surface and drilling is performed. 3. The metal foil-clad resin composite ceramic plate,
The method for producing a resin composite ceramics printed wiring board according to claim 1, which is a metal foil clad nitride resin composite ceramics board. 4. The method for producing a resin composite ceramics printed wiring board according to claim 2, wherein said protective coat is a cellulose-based pressure-sensitive adhesive tape or a coating film of a cellulose-based or acrylic resin-based paint. 5. The method for producing a resin composite ceramics printed wiring board according to claim 1, wherein the surface irregularities of the through-hole hole wall are 2 μm or less by cross-sectional observation. 6. The method according to claim 1, wherein the through-hole plating is a direct plating copper plating using a palladium colloid or a palladium-tin colloid.