JP2001332857A - Manufacturing method for wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that burrs, chips, etc., are formed and an outward appearance defect is generated when a ceramic substrate is parted into individual wiring boards. SOLUTION: When one ceramic substrate 7 are cut and parted along parting grooves 6 to form many wiring boards 9, plural cavities 5 are formed vertically side by side in areas of the ceramic substrate 7 right below the parting grooves 6, within a range defined by 0.24×(t-c1-c2)<=nd<=0.38×(t-c1-c2) and d<=0.62×1+log(c1/w)} (t: thickness (mm) of insulating base body, c1: depth (mm) of parting groove on cutting start point side, c2: depth (mm) of parting groove on cutting end-point side, w: maximum opening width (mm) of parting groove, n: number of cavities, d: vertical internal diameter (mm) of each cavity part).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board on which electronic components such as a semiconductor element, a capacitor, and a resistor are mounted.

[0002]

2. Description of the Related Art Conventionally, a wiring board on which electronic components such as a semiconductor element, a capacitor element, and a resistor are mounted has an insulating base made of an electrically insulating material such as an aluminum oxide sintered body, and has tungsten, molybdenum, etc. It has a structure in which a wiring conductor layer made of a high melting point metal material is formed, and electronic components such as semiconductor elements, capacitance elements, and resistors are mounted on the surface of the insulating base, and the electrodes of each electronic component are electrically connected to the wiring conductor. Connection is made.

Such a wiring board is generally manufactured by employing a technique of laminating ceramics and a technique of forming a thick film such as screen printing, and especially in a small-sized wiring board for surface mounting or the like, mass production is taken into consideration. It is manufactured by a method of dividing a ceramic substrate manufactured in a multi-piece form in which a large number of pieces are integrated, and specifically manufactured by the following method. That is, (1) First, an organic solvent and a solvent are added to and mixed with a ceramic raw material powder composed of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), calcium oxide (CaO) and the like. A plurality of wide-area ceramic green sheets (green ceramic sheets) having a large number of regions serving as insulating bases of a wiring board are formed by forming a slurry and forming the same into a sheet by a well-known doctor blade method, a calendar roll method, or the like. obtain. (2) Next, a conductive paste obtained by adding an organic solvent and a solvent to a powder of a metal such as tungsten or molybdenum is applied by screen printing to the at least one ceramic green sheet in a region to be each insulating substrate. A wiring conductor is adhered and formed by printing on a predetermined pattern. (3) Next, the ceramic green sheets are stacked up and down to form a green ceramic molded body, and on the upper surface and / or lower surface of the green ceramic molded body, along a virtual line defining the region to be the insulating base. A division groove is formed by pressing a metal blade, and the division groove is used to divide the region to be the insulating base. (4) Finally, the green ceramic molded body is fired to obtain a ceramic substrate having a large number of wiring boards in which wiring conductors are formed on an insulating base, and the ceramic substrate is cut along the dividing grooves to obtain a large number of pieces. By individually dividing the wiring boards, individual wiring boards having a predetermined pattern of wiring conductors are formed.

In the cutting of the ceramic substrate, usually, the ceramic substrate is bent along the dividing line to concentrate the bending stress on the bottom of the dividing groove, thereby generating a small crack at the bottom of the dividing groove and forming the crack. This is performed by advancing to the bottom through the inside of the ceramic substrate.

[0005]

However, according to the above-mentioned conventional manufacturing method, when the ceramic substrate is divided along the dividing grooves, the shape of the sintered particles forming the ceramic substrate is reduced.
Due to variations in physical properties, etc., the crack propagation direction becomes uneven, and as a result, the ceramic substrate cannot be accurately divided along the dividing grooves, and the formed individual wiring substrate has burrs, chips, etc. Is formed to cause a defective outer shape.

In particular, when the wiring board is small and the wiring conductors are formed at a high density, the outer size (outer dimension) of the wiring board is the standard value even if the generated burrs and chips are small. Of the wiring conductor, or a serious problem such as disconnection of the wiring conductor occurs.

The present invention has been devised in view of the above problems, and an object of the present invention is to cut a ceramic substrate along a dividing groove reliably and neatly without generating burrs and chips. It is an object of the present invention to provide a method of manufacturing a wiring board, which is capable of forming a large number of wiring boards having predetermined wiring conductors and predetermined external dimensions at a time.

[0008]

According to the present invention, there is provided (1) a method of preparing a plurality of wide-area ceramic green sheets having a large number of regions serving as insulating bases of a wiring board; (2) a step of laminating the plurality of ceramic green sheets one above the other to form a green ceramic molded body, and (3) an upper surface of the green ceramic molded body. And / or forming a dividing groove on the lower surface, and dividing the region serving as the insulating base by the dividing groove; and (4) firing the green ceramic molded body having the dividing groove formed thereon, and forming a wiring conductor on the insulating base. Obtaining a ceramic substrate having a large number of wiring boards on which a plurality of wiring boards are formed, cutting the ceramic substrate along the division grooves, and individually dividing the large number of wiring boards. A method of manufacturing a wiring board having a said ceramic substrate is aligned plurality of hollow portion up and down inside the region immediately below the dividing grooves, and the following formula (1)
It is characterized by being formed so as to satisfy (2). (Equation 1) 0.24 × (t−c1−c2) ≦ nd ≦ 0.38 × (t−c1−c2) (Equation 2) d ≦ 0.62 × {1 + log (c1 / w)} where t : The thickness of the insulating substrate (mm) c1: the depth of the dividing groove on the cutting start side (mm) c2: the depth of the dividing groove on the cutting end side (mm) w: the maximum opening width of the dividing groove (mm) n: cavity Number of parts d: vertical inner diameter (mm) of each cavity part In the present invention, the plurality of cavities are each substantially cylindrical and formed so as to be parallel to the dividing groove. It is characterized by the following.

According to the method of manufacturing a wiring board of the present invention, since a plurality of cavities under predetermined conditions are formed inside a region located immediately below the dividing groove provided in the ceramic substrate, the ceramic substrate is bent by bending. When applying stress and cutting along the dividing groove, the traveling direction of small cracks formed at the bottom of the dividing groove is sequentially corrected by bending stress concentrated on the upper end and lower end of each cavity. It is directly below the dividing groove of the ceramic substrate, and as a result, it is possible to cut the ceramic substrate along the dividing groove reliably and neatly without generating burrs, chips, etc. A large number of wiring boards having dimensions can be formed at one time.

Further, according to the method of manufacturing a wiring board of the present invention, the cavity is formed in an optimum condition for the thickness of the ceramic substrate, that is, 0.24 × (t−c1−c2) ≦ nd ≦.
0.38 × (t−c1−c2) and d ≦ 0.62 × ｛1
+ Log (c1 / w)｝ (t: thickness of insulating substrate (m
m), c1: Depth (mm) of the dividing groove on the cutting start side, c
2: the depth (mm) of the dividing groove on the cutting end point side, w: the maximum opening width (mm) of the dividing groove, n: the number of cavities, d: the vertical inner diameter (mm) of each cavity. From the specified range, the ceramic substrate can be cut reliably and neatly without generating burrs, chips, etc. along the dividing groove while maintaining good mechanical strength of the dividing groove forming portion of the ceramic substrate. It is possible to form a large number of wiring boards having predetermined wiring conductors and predetermined external dimensions at one time.

[0011]

Next, a method for manufacturing a wiring board according to the present invention will be described in detail with reference to the embodiment shown in FIG.

First, as shown in FIG. 1A, a concave portion 2 serving as a cavity is formed on an upper surface and / or a lower surface along an imaginary line defining a region A serving as an insulating base, which includes a plurality of regions A serving as an insulating base. At the same time, a wiring conductor 3 having a predetermined pattern is formed in a region A serving as an insulating base of at least one ceramic green sheet.

For example, when the insulating substrate is formed of an aluminum oxide sintered body, the ceramic green sheet 1 may be made of aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), magnesium oxide (MgO), Ceramic powder such as calcium oxide (CaO), glass powder,
An organic solvent and a solvent are added to and mixed with a raw material powder comprising a coloring auxiliary powder such as molybdenum oxide to form a slurry, which is formed into a sheet by a conventionally known doctor blade method, a calendar roll method, or the like. It is formed.

The recess 2 has a substantially semicircular shape in the thickness direction of the ceramic green sheet 1. For example, a rod-shaped metal member having a substantially cylindrical shape is formed at a predetermined position on the ceramic green sheet 1 by a predetermined depth. Formed by pressing up to.

Further, the wiring conductor 3 is made of tungsten,
Made of metal powder such as molybdenum, manganese, copper, silver, etc.
A metal paste obtained by adding and mixing an appropriate organic binder and a solvent to a metal powder such as tungsten is formed by printing and applying a predetermined pattern on a region A serving as an insulating substrate of the ceramic green sheet 1 by a conventionally known screen printing method. Is done.

Next, as shown in FIG. 1 (b), a plurality of ceramic green sheets 1 are stacked one on top of the other so that concave portions 2 serving as cavities provided on the upper and lower surfaces thereof face each other. A green ceramic molded body 4 having a wiring conductor 3 in a region A serving as an insulating base and having a plurality of vertically arranged cavities 5 therein is formed.

Next, as shown in FIG. 1 (c), a division groove 6 is formed on the upper and lower surfaces of the green ceramic molded body 4 along an imaginary line dividing an area A to be an insulating base.

The dividing groove 6 is formed, for example, by pushing a metal blade into the upper and lower surfaces of the green ceramic molded body 2 to a predetermined depth. In this case, the formed dividing groove 6 has a V-shape or the like. Has a cross-sectional shape substantially similar to the longitudinal cross-section of the blade.

The dividing groove 6 is usually formed so as to reach the outer peripheral edge of the green ceramic molded body 4 so that the ceramic substrate can be easily cut along the dividing groove in a later step. .

Next, the green ceramic molded body 4 is fired, for example, in a reducing atmosphere at a temperature of about 1600 ° C.
As shown in (d), the insulating substrate B has a large number of wiring boards 9 on which wiring conductors 8 of a predetermined pattern are formed, and each wiring board 9 is divided by the dividing grooves 6 and is directly below the dividing grooves 6 ( (Directly above) a plurality of hollow portions 5 under predetermined conditions
Are obtained to obtain a ceramic substrate 7 arranged vertically.

Finally, when the ceramic substrate 7 is cut along the dividing grooves 6, each of the individual conductors having a predetermined pattern of the wiring conductors 8 attached to the insulating substrate B is formed as shown in FIG. The wiring board 9 is formed.

The cutting of the ceramic substrate 7 deflects the ceramic substrate 7 along the dividing groove 6 to concentrate bending stress on the bottom of the dividing groove 6, thereby causing a small crack at the bottom of the dividing groove 6. The crack is formed by advancing the crack inside the ceramic substrate 7. In this case, since the plurality of cavities 5 are formed in the ceramic substrate 7 in the region immediately below the dividing groove 6 in a vertical direction, the bending direction is such that bending stress is applied to each of the cavities 5. By concentrating at the upper end and the lower end, it is sequentially corrected for each short traveling distance, and is always in a direction directly below the dividing groove 6 of the ceramic substrate 7. As a result, the ceramic substrate 7 is moved along the dividing groove 6 such as burrs and chips. Can be cut reliably and neatly without generating a predetermined wiring conductor 8,
A large number of wiring boards 9 having predetermined external dimensions can be formed at one time.

The plurality of cavities 5 have a total sum of the inner diameters in the vertical direction that is the optimum size for the thickness of the insulating substrate 1 at the portion where the division groove 6 is formed, that is, 0.24 × (t−c).
1−c2) ≦ n · d ≦ 0.38 × (t−c1−c2), and the upper limit of the inner diameter in the vertical direction is d ≦ 0.62 × ｛1 + log ( c1 /
w) Since it was specified in the range that な る (however,
t: thickness of the insulating base (mm), c1: depth (mm) of the dividing groove 6 on the starting point of cutting, c2: depth (mm) of the dividing groove 6 on the ending point of cutting, w: maximum opening of the dividing groove 6 Width (mm), n:
Number of cavities 5, d: vertical inner diameter of each cavity 5 (m
m)), while maintaining the mechanical strength of the divided groove forming portion of the ceramic substrate in good condition, it is possible to cut reliably and neatly without generating burrs and chips along the divided grooves.

Note that nd <0.24 × (t−c1−c)
2) In other words, if the total of the inner diameters of the hollow portion 5 in the vertical direction is less than 24% of the thickness of the insulating base at the portion where the division groove 6 is formed, it is not possible to satisfactorily correct the crack propagation direction,
Burrs and chips are generated on the obtained wiring board 9 and n.
When d> 0.36 × (t−c1−c2), that is, when the sum of the vertical inner diameters of the cavity portions 5 exceeds 36% of the thickness of the insulating base at the division groove 6 formation site, the division groove formation is performed. The mechanical strength of the insulating substrate 1 at the site is deteriorated, and the insulating substrate 1 is broken by an impact applied during transportation and handling. Therefore, the hollow portion 5 is 0.24 × (t−c1−c2).
≦ nd · 0.38 × (t−c1−c2).

The vertical inner diameter d of each hollow portion 5
Is larger than d> 0.62 × {1 + log (c1 / w)}, the mechanical strength of the insulating substrate 1 is reduced, and the insulating substrate 1 is broken by an impact applied during transportation and handling. Therefore, the hollow part 5 is d ≦ 0.62 × ｛1 + 1
og (c1 / w)}.

Furthermore, if the cavity 5 is formed in a substantially columnar shape, and is formed so as to be vertically parallel to the dividing groove 6, a bending stress due to bending is applied to the ceramic substrate 7, and When cutting along the line 6, the bending stress can be easily concentrated on the upper end and the lower end of each cavity, so that the direction of progress of the crack can be corrected more accurately right below the dividing line 6.

On the wiring board 9 thus obtained, electronic components such as semiconductor elements, capacitance elements and resistors are mounted on the upper surface of the insulating base B, and the electrodes of each electronic component are electrically connected to the wiring conductor 8. Thus, each of the electronic components is electrically connected to each other via the wiring conductor 8 and connected to an external electric circuit. It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. For example, in the above-described embodiment, three hollow portions are formed. As described in the above, the cavity is formed by 4 depending on the thickness of the ceramic substrate 7 or the like.
One or more divided grooves 6 may be formed on the upper or lower surface of the green ceramic molded body 4, or the upper and lower divided grooves 6 may be formed.
May be made different in depth.

[0028]

According to the method of manufacturing a wiring board of the present invention,
Since a plurality of cavities under predetermined conditions are formed inside the region located immediately below the dividing groove provided in the ceramic substrate, bending stress due to bending is applied to the ceramic substrate, and when cutting along the dividing groove, the dividing is performed. The traveling direction of the small cracks formed at the bottom of the groove is gradually corrected by the bending stress being concentrated on the upper end and the lower end of each cavity, and is directed directly below the divided groove of the ceramic substrate. Can be cut reliably and neatly without generating burrs, chips, etc. along the dividing grooves, and a large number of wiring boards having predetermined wiring conductors and predetermined external dimensions can be formed at a time. .

Further, according to the method of manufacturing a wiring board of the present invention, the cavity is formed in an optimum condition for the thickness of the ceramic substrate, that is, 0.24 × (t−c1−c2) ≦ nd ≦.
0.38 × (t−c1−c2) and d ≦ 0.62 × ｛1
+ Log (c1 / w)｝ (t: thickness of insulating substrate (m
m), c1: Depth (mm) of the dividing groove on the cutting start side, c
2: the depth (mm) of the dividing groove on the cutting end point side, w: the maximum opening width (mm) of the dividing groove, n: the number of cavities, d: the vertical inner diameter (mm) of each cavity. From the specified range, the ceramic substrate can be cut reliably and neatly without generating burrs, chips, etc. along the dividing groove while maintaining good mechanical strength of the dividing groove forming portion of the ceramic substrate. It is possible to form a large number of wiring boards having predetermined wiring conductors and predetermined external dimensions at one time.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views for explaining steps of a method for manufacturing a wiring board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic green sheet 2 ... Depression 3 ... Wiring conductor A ... Area to be an insulating base 4 ... Green ceramic molded body 5 ... Cavity 6 ... ... Division groove 7 ... Ceramic substrate B ... Insulating substrate 8 ... Wiring conductor 9 ... Wiring board

Claims (2)

[Claims] (1) A plurality of wide-area ceramic green sheets each having a large number of regions serving as insulating bases of a wiring board are prepared, and a wiring area is provided in each of the at least one ceramic green sheet as an insulating base. A step of applying and forming a conductor; (2) a step of laminating the plurality of ceramic green sheets up and down to form a green ceramic molded body; and (3) forming a dividing groove on an upper surface and / or a lower surface of the green ceramic molded body. Forming and dividing the region to be the insulating substrate by the dividing groove; and (4) firing a green ceramic molded body having the dividing groove formed thereon to form a large number of wiring substrates having wiring conductors formed on the insulating substrate. A step of obtaining a ceramic substrate, cutting the ceramic substrate by applying bending stress along the division groove, and dividing a large number of wiring substrates individually Wherein the ceramic substrate has a plurality of cavities vertically arranged inside a region immediately below the division groove and satisfies the following formulas (1) and (2). A method for manufacturing a wiring board, characterized by being formed as follows. (Equation 1) 0.24 × (t−c1−c2) ≦ nd · 0.33 × (t−c1−c2) (Equation 2) d ≦ 0.62 × {1 + log (c1 / w)} where T: Thickness of insulating substrate (mm) c1: Depth of dividing groove on cutting start side (mm) c2: Depth of dividing groove on cutting end point side (mm) n: Number of cavities d: Number of cavities Vertical inner diameter 2. The method according to claim 1, wherein the plurality of cavities are each formed in a substantially cylindrical shape and in parallel with the dividing groove.