JP2003101225A - Ceramic substrate and divided circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic substrate capable of improving the connecting reliability of a wiring layer to an end face electrode and to provide a divided circuit board. SOLUTION: The ceramic substrate comprises an insulating base 21 obtained by laminating a plurality of insulating layers 21a to 21h, dividing grooves 17 formed on the surface of the base 21, and a dividing circuit board having punched holes 27 formed in a thickness direction of the base 2 and formed on the grooves 17 and having a plurality of end face electrodes 2 formed when the base 21 is divided at the grooves 17. The substrate further comprises a plurality of columnar conductors 9 partly exposed to the holes 27 and formed at a predetermined interval in such a manner that the conductors 9 of the upper and lower adjacent insulating layers 21a to 21h are partly superposed as seen from above the base 21, and the superposed parts of the conductors 9 are exposed to the holes 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate and a divided circuit board which are divided circuit boards each having a plurality of end face electrodes when divided into unit blocks.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and lighter and more portable, and circuit blocks used therein have been made smaller, lighter and thinner, surface-mounted, and compounded in response to the trend. .

In such a trend, the ceramic circuit board is widely used because of its excellent heat dissipation and low dielectric loss, and its application as a high frequency module is being promoted.

A ceramic circuit board for a high frequency module is used by being soldered to a mother board. The end surface electrodes are formed on the ceramic circuit board and have a role of fixing to the mother board and transmitting signals. And
From the viewpoint of the manufacturing method, there are roughly two types of manufacturing methods for the structure of the end face electrode.

The first method is a structure called a through-hole thick film structure, in which a technique such as suction is used in combination with a fired ceramic circuit board on which through holes for end face electrodes have already been formed, and a thick film printing technique or the like. The conductive paste is coated on the inner wall surface of the through hole, and then baked. The advantage of this method is that a large number of substrates can be processed, that is, when divided into unit blocks, each can be a divided circuit substrate having a plurality of end face electrodes, which is advantageous in reducing the number of steps.

The second structure is an application of the first structure, in which a through hole is formed in each green sheet of green sheets, and the inner wall surface of the through hole is coated with a conductive paste, and the through hole is formed. This is a structure achieved by laminating and integrating a hole thick film structure. The advantage is that the wiring layer and the end face electrode can be easily joined.

[0007]

However, in the above-mentioned through-hole thick film structure, in the case where the ceramic substrate has a wiring layer, it is necessary to form the through-holes after being laminated on the unfired ceramic substrate. , It is necessary to form by a punching method using a die, but at the punching hole forming position, the wiring layer and the green sheet are alternately formed in the stacking direction, and moreover, the wiring layer is formed at the punching hole forming position. Since there is a large proportion of the part that is not formed and only the green sheet is formed in the stacking direction, when punching with the mold, the green sheet with higher strength pushes the end of the wiring layer in the punching direction and the wiring layer collapses, and the end surface There is a problem that it is difficult to make contact with the electrodes.

Further, when a through hole is formed in each green sheet layer, the inner wall surface of the through hole is coated with a conductive paste, and finally the layers are laminated and integrated, a deviation of the lamination of the green sheets occurs. However, the inner wall surface of the through-hole becomes uneven, and the surface of the end face electrode also tends to become uneven, and similarly, there is a problem that the connection reliability between the wiring layer and the end face electrode decreases.

It is an object of the present invention to provide a ceramic substrate and a divided circuit substrate which can improve the connection reliability between the wiring layer and the end face electrode.

[0010]

A ceramic substrate according to the present invention comprises an insulating substrate formed by laminating a plurality of insulating layers made of ceramics, a wiring layer formed between the insulating layers, and a via hole connected to the wiring layer. A conductor, a dividing groove formed on the surface of the insulating base, and a punching hole formed in the thickness direction of the insulating base and formed on an extension line of the dividing groove. Is a ceramic substrate that becomes a divided circuit board each having a plurality of end face electrodes when divided into, and a columnar conductor that is partially exposed in the punched hole along the punched hole in the thickness direction of each insulating layer. A plurality of columnar conductors of the upper and lower insulating layers that are adjacent to each other partially overlap each other when viewed from above the insulating base, and the overlapped portion of the columnar conductors is exposed in the punched hole. That And butterflies.

In the ceramic substrate of the present invention, columnar conductors are continuously arranged at a predetermined interval centering on a punching hole punched by a die after the insulating layer molded body is laminated. Then, when the punching holes are punched out by the mold after the lamination of the insulating layer molded body is completed, a part of the columnar conductor formed in the thickness direction of the insulating layer molded body becomes the punching surface of the mold, so that The portion is removed, and a part of the columnar conductor is exposed on the inner surface of the punched hole.

Further, since the columnar conductors formed in the respective insulating layers are formed by the columnar conductors formed in the adjacent upper and lower insulating layers overlapping each other, the columnar conductors are formed on the cut surface of the punched hole. Are continuously formed between the upper and lower surfaces of the insulating base. Therefore, the insulating layer molded body does not exist continuously in the thickness direction on the cut surface, and columnar conductors penetrating in the thickness direction are formed in each insulating layer. Since it is connected through the overlapping portion, the proportion of the insulating layer to be punched is small, and there is almost no extra stress or deformation that acts on the insulating layer during punching, and the wiring layer and the end face electrode The connection reliability can be improved.

Further, the amount of the conductor used can be reduced and an inexpensive substrate can be manufactured as compared with the conventional case where the conductor layer is formed on the entire inner surface of the punched hole.

Furthermore, since the punching is carried out in a batch after the lamination of the insulating layer molded body is completed, there is no connection failure due to the influence of the stacking deviation of the punching holes as in the conventional case, and each columnar conductor is inside the insulating substrate. Since they are electrically connected, it is possible to provide an end face electrode with high connection reliability.

In the present invention, the columnar conductor of the insulating layer is
It is desirable to have a wide portion in which the width gradually increases from the exposed portion inside the punched hole toward the inside of the insulating layer. As a result, the columnar conductor is anchored to the insulating base, can be prevented from falling off from the insulating base, and the connection strength of the end face electrode to the insulating base can be improved.

Further, in the present invention, it is desirable that the columnar conductor of the insulating layer is formed excluding the dividing groove when viewed from above the insulating substrate. As a result, when divided by the dividing groove, it is divided by the insulating layer, and the columnar conductor is exposed in the recess, but is not exposed on the outer peripheral surface of the divided insulating substrate. The columnar conductor does not peel off or fall off due to collision with an external object.

The divided circuit board of the present invention is formed by forming an end face electrode in a concave portion formed on the outer peripheral surface of a divided insulating substrate formed by laminating a plurality of insulating layers made of ceramics and in the thickness direction. In the divided circuit board, the end face electrode is formed by forming a plurality of columnar conductors partially exposed in the recess along the recess at predetermined intervals in the thickness direction of each insulating layer, and adjacent to each other. The columnar conductors of the upper and lower insulating layers partially overlap with each other when viewed from above the divided insulating substrate,
The overlapping portion of the columnar conductor is exposed in the recess.

In such a divided circuit board, it is possible to improve the connection reliability between the wiring layer and the end face electrode, as in the ceramic board described above.

Further, it is desirable that a metal layer is formed in the recess of the divided insulating substrate. Since this metal layer is formed on the entire surface of the concave portion including the exposed portion of the columnar conductor, it is possible to firmly bond the divided circuit board when soldering it to the mother board.

[0020]

FIG. 1 is a perspective view of a divided circuit board formed by dividing a ceramic substrate of the present invention by dividing grooves. Reference numeral 1 indicates a divided insulating base, and an input / output terminal. Terminals such as a power supply terminal and a ground terminal are shown as the end surface electrodes 2. The end surface electrode 2 is formed so as to be exposed on the side surface of the divided insulating base 1.

A surface electrode (wiring) 3 is formed on the upper surface of the divided insulating substrate 1, and a chip component 4 such as a resistor, a capacitor or an inductor is connected to the surface electrode 3.

Further, the divided insulating substrate 1 has a cavity 5
The semiconductor bare chip 6 is housed in the cavity 5 and is connected to the surface electrode 3 by a wire.

In the split circuit board of the present invention, a plurality of recesses 7 are formed on the outer peripheral surface of the split insulating substrate 1 in the thickness direction thereof, and as shown in FIG. 2 is formed. The end surface electrode 2 is formed by forming a plurality of columnar conductors 9 that are partially exposed in the recesses 7 along the recesses 7 at predetermined intervals in the thickness direction of each of the insulating layers 1a to 1h that form the divided insulating substrate 1. The upper and lower insulating layers 1a
The columnar conductors 9 of 1 h overlap with each other when viewed from above the divided insulating substrate 1, and the overlapped portion 11 of the columnar conductor 9 is also exposed in the recess 7.

That is, the columnar conductor 9 has a shape in which a part of the cylinder is removed by the recess 7, and from the exposed portion,
A wide portion 10 having a width that increases toward the inside of the insulating layers 1a to 1h is formed. Part of the columnar conductor 9 is exposed in the recess 7 so as to form a lattice, and the overlapping portion 11
The columnar conductors 9 are electrically connected to each other in the thickness direction of the divided insulating base body 1 and in the lateral direction. Thereby, the end face electrode 2 is formed. In the case of FIG. 1, the metal layer 8 is formed on the surface of the concave portion 7 where the columnar conductor 9 is exposed to the outside and the surface of the divided insulating substrate 1 in which the concave portion 7 is formed. Although the metal layer 8 need not be formed, it is desirable to form the metal layer 8 from the viewpoint of joining to the mother board by soldering. A plurality of columnar conductors 9 are formed on each of the insulating layers 1a to 1h, but a wiring layer is connected to at least one of the columnar conductors 9 formed on each of the insulating layers 1a to 1h.

FIG. 3 is a perspective view of the ceramic substrate of the present invention, in which a dividing groove 17 is formed in this ceramic substrate, and a punching hole 19 is formed on an extension line of the dividing groove 17. By dividing this ceramic substrate along the dividing groove 17, the divided circuit substrate shown in FIG. 1 is obtained.
In FIG. 3, the punching hole 19 is simplified for convenience.

As shown in FIG. 4, the insulating substrate 21 of the ceramic substrate has insulating layers 21a to 21h, a wiring layer 23,
And the insulating layer 21.
a to 21h are made of, for example, ceramic or glass ceramic material, and each has a thickness of 40 to 150 μm.
It is said that.

The insulating layer 21b and the insulating layer 21c,
Insulating layer 21d and insulating layer 21e, insulating layer 21f and insulating layer 2
The wiring layer 23 is formed between 1g. Wiring layer 23
Is made of a gold-based, silver-based, or copper-based metal material, for example, a silver-based conductor. The wiring layer 23 may be connected by the via-hole conductor 24, or may be connected in a distributed constant manner by capacitive coupling or the like. This via hole conductor 2
Similarly to the wiring layer 23, 4 is a metal material of gold, silver or copper,
For example, it is made of a silver-based conductor.

As shown in FIG. 5A, the ceramic substrate has a plurality of circular punched holes 27 formed in the dividing groove 17, and the punched holes 27 have a plurality of columnar conductors. Part of 9 is exposed and becomes the end face electrode 2 when divided by the dividing groove 17.

The inner surface of the punching hole 27 is shown in FIGS.
As shown in, in the thickness direction of each of the insulating layers 21a to 21h,
The columnar conductor 9 partially exposed in the punching hole 27 is
A plurality of columnar conductors 9 of the upper and lower insulating layers 21a to 21h are formed at predetermined intervals along the line and partially overlap each other when viewed from above the insulating substrate 21, and the overlapped portion 11 of the columnar conductor 9 is formed in the punching hole 27. Is exposed to. The punched holes 27 may have an elliptical cross section as shown in FIG. 5C, and the arrangement of the columnar conductors 9 in this case is as shown in FIG. 5D.

A method of manufacturing the ceramic substrate of the present invention will be described with reference to FIG. First, a slip material to be the insulating layers 21a to 21h is manufactured. The slip material is, for example, glass ceramics or ceramic raw material powder, a photocurable monomer such as polyoxyethylated trimethylolpropane triacrylate, an organic binder such as alkyl methacrylate, a plasticizer, and an organic solvent such as ethyl carbyl. It is prepared by mixing with tall acetate and kneading with a ball mill.

The raw material powder is, for example, a composite oxide containing at least Mg, Ti, and Ca as metal elements, and the composition formula of the metal element oxide is (1-x).
Main component 10 represented by MgTiO ₃ —xCaTiO ₃ (where x represents a weight ratio, 0.01 ≦ x ≦ 0.15)
With respect to 0 part by weight, the boron-containing compound is 3 to _{3 in} terms of B ₂ O 3.
The one containing 30 parts by weight and 1 to 25 parts by weight of the alkali metal-containing compound in terms of alkali metal carbonate is used.

Although a solvent-based slip material is prepared in the above, a photo-curable monomer having a hydrophilic functional group added thereto, for example, a polyfunctional methacrylate monomer, an organic binder such as a carboxyl-modified alkyl methacrylate is used. Alternatively, a water-based slip material kneaded with ion-exchanged water may be used.

As the raw material powder, for example, 70% by weight of crystallized glass powder containing SiO ₂ , Al ₂ O ₃ , ZnO, MgO, and B ₂ O ₃ which are glass materials as main components and alumina powder 30 which is a ceramic material are used. Also used are those consisting of wt%. The raw material powder is not particularly limited.

Further, the columnar conductor 9, the via-hole conductor 24,
A conductive paste to be the wiring layer 23 and the surface electrode 3 is prepared. The conductive paste is a low melting point and low resistance metallic material such as silver powder and borosilicate low melting point glass such as B ₂ O ₃ —SiO ₂ —BaO glass and CaO—B ₂ O _3.
-SiO _{2 glass, CaO-Al 2 O 3 -B} 2 O 3 -SiO 2
Glass and an organic binder such as ethyl cellulose are mixed with an organic solvent such as 2,2,4-trimethyl-1,3.
-Mixed with pentadiol monoisobutyrate and homogeneously kneaded with three rollers.

The manufacturing method of the ceramic substrate of the present invention is as follows.
As shown in FIG. 6A, the above-mentioned conductive paste is applied onto the support substrate 35 to form the conductor layer 36 which becomes the surface electrode 3, and then the above-mentioned slip material is applied by the doctor blade method. -Drying forms the insulating layer molded body 41a which forms the insulating layer 1a. Here, a Mylar film is used as the support substrate 35 and is removed before the firing step.

Next, as shown in FIG. 6B, the insulating layer molded body 41a is formed.
As shown in FIG. 3, through holes 43a and 45a for forming the columnar conductor 9 and for forming the via hole conductor 24 are formed. Through hole 43a for forming the columnar conductor 9
Is a through hole 43 having a circular cross section, as shown in FIG.
A plurality of “a” are formed in a ring shape at predetermined intervals so as to straddle the dividing groove 17. A punching hole 27 described later is shown by a broken line. The dividing groove 17 is not formed on the insulating layer molded body 41a, but is described for convenience. The through hole 43a for forming the columnar conductor 9 may be formed along the punched hole 27 having an elliptical cross section, as shown in FIG. 7B.

The through holes 43a and 45a are formed by exposure processing, development processing, and cleaning / drying processing. The exposure process is performed by placing a photo target on the insulating layer molded body 41a such that the regions where the through holes 43a and 45a are formed are shielded from light, and, for example, an ultra-high pressure mercury lamp (10 mW / cm ² ).
Is used as a light source to perform exposure.

As a result, in the insulating layer molded body 41a in the regions where the through holes 43a and 45a are formed, the photopolymerization reaction of the photocurable monomer does not occur, and the through holes 43a and 4a are formed.
In the insulating layer molded body 41a other than the region where 5a is formed, a photopolymerization reaction occurs. The portion where the photopolymerization reaction has occurred is called the insolubilized portion, and the portion where the photopolymerization reaction does not occur is called the solubilized portion.

The developing treatment is to remove the solubilized portion of the insulating layer molded body 41a with a developing solution. Specifically, for example, spray developing is carried out using an aqueous solution of triethanolamine as a developing solution. By this development processing, the insulating layer molded body 41a
Through holes 43a and 45a can be formed in the.

Next, the through holes 43a and 45a are filled with a conductive paste and dried to form the via hole conductors 24 and the conductive members 47a and 49a to be the columnar conductors 9. Specifically, as shown in FIG. 6C, the above-mentioned conductive paste is filled in the through holes 43a and 45a formed in the above-described process and dried. Conductive members 47a and 49a are formed by printing using a screen that can be printed only on the portions corresponding to the through holes 43a and 45a, and then dried at 80 ° C. for 10 minutes.

Next, the insulating layer molded body 41b is formed on the upper surface of the insulating layer molded body 41a on which the via-hole conductor 24 and the conductive members 47a and 49a to be the columnar conductors 9 are formed in the same manner as described above.
Through holes 43b, 45b for forming columnar conductors 9 therein and for forming via hole conductors 24
Are formed in the same manner as described above.

The through hole 43 for forming the columnar conductor 9 in the insulating layer molded body 41b is provided with a conductive member for the columnar conductor 9 formed in the lower insulating layer molded body 41b as shown by a broken line in FIG. It is formed so as to partially overlap. After that, the conductive paste is filled in the through holes 43b and 45b to form a conductive member.

By repeating the above steps, a laminate having the insulating layer molded bodies 41a to 41g formed thereon is produced. After this, apply the slip material by the doctor blade method.
By drying, the outermost surface insulating layer molded body 41h of the insulating substrate 1 is formed.

The insulating layer molded body 41h is subjected to the above-mentioned exposure treatment and a conductive paste is applied to form a surface electrode.

The laminated molded body thus produced is
If necessary, the shape is adjusted by a press to obtain a molded body as shown in FIG. 6 (e). After that, the support substrate 35 is removed.

Next, punching holes 27 are formed. As a method, a punching method with a die is preferable, but a method using a drill is also practical. This punching hole 27 is
The cut surface is formed at the position where the columnar conductor 9 of the end face electrode portion is divided, as shown by the broken line in FIG. As a result, a part of the columnar conductor 9 is exposed on the surface of the punched hole 27, and a wide portion 10 whose width gradually increases from the exposed portion toward the inside is formed. In the case of the columnar conductor 9 having a circular cross section and the punched hole 27, the wide portion 10 has the columnar conductor 9
It is formed by punching so that the center of the remains.

That is, they are formed inside the columnar conductors 9 formed at predetermined intervals in a circular shape and at a position inside the center of each columnar conductor 9. In other words,
The size of the punching hole 27 is set so that the area of the portion punched by the punching hole 27 is smaller than that of the remaining portion.

Next, a technique such as suction is used for the punching hole 27,
The inner wall surface is coated with a conductive paste.

Thereafter, dividing grooves 17 for dividing into circuit blocks are formed on both sides of the laminated molded body. Dividing groove 1
7 is formed by pressing a sharp blade at a position where the punched hole 27 is divided into two.

Finally, firing is performed. The firing process consists of a binder removal process and a firing process.
(.Degree. C.), the organic components of the insulating layer molded body, the wiring layer pattern, the end face electrodes, and the conductive members of the via-hole conductor disappear. After that, the insulating layer molded body and the wiring layer pattern, the end surface electrodes, the via hole conductors, and the columnar conductors, which become the insulating layer, are collectively fired in a predetermined atmosphere and at a predetermined temperature.

After that, as the surface treatment, printing / baking of a thick film resistance film or a thick film protective film, plating treatment, and joining of chip components 4 and 6 including an IC chip are further performed.

The surface electrode 3 may be printed and dried on the surface of the fired laminate of the insulating layers 1a to 1h and baked in a predetermined atmosphere. For example, when an Ag-based conductor is used for the wiring layer 23 and a Cu-based conductor is used for the surface electrode 3, a laminate including the insulating layers 21a to 21h and the conductor film of the wiring layer 23 is fired in an oxidizing atmosphere or a neutral atmosphere. Then, a Cu-based conductor is printed and dried on the surface of the fired laminated body, and a neutral atmosphere or a reducing atmosphere at 780 ° C. (Ag and C
firing at a temperature equal to or lower than the (eutectic point of u).

In the above embodiment, the slip is applied on the supporting substrate and dried to form the insulating layer molded body,
Although the through holes were formed by exposure and development, a dielectric green sheet was formed, the through holes were formed in this green sheet by punching of a mold, and this was filled with a conductive paste, and this conductive paste was filled. Needless to say, the ceramic substrate may be manufactured by a so-called green sheet laminating method in which green sheets are laminated.

[0054]

According to the ceramic substrate of the present invention, a plurality of columnar conductors partially exposed in the punching hole are formed along the punching hole at predetermined intervals in the thickness direction of each insulating layer, and adjacent columnar conductors are formed. Since the columnar conductors of the insulating layer partially overlap with each other when viewed from above the insulating substrate, and the overlapping portions of the columnar conductors are exposed in the punching holes, extra stress or deformation acting on the insulating layer during punching is prevented. Almost no occurrence occurs, the wiring layer collapses, and the connection reliability between the wiring layer and the end face electrode can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a divided circuit board of the present invention.

2 is a perspective view showing an end face electrode portion of FIG. 1 with a metal layer removed. FIG.

FIG. 3 is a perspective view showing a ceramic substrate of the present invention.

FIG. 4 is a sectional view showing a part of FIG. 3 in an enlarged manner.

FIG. 5 is a view showing a punching hole of the ceramic substrate of the present invention and the vicinity thereof.

FIG. 6 is a process chart showing a method for producing a ceramic substrate of the present invention.

FIG. 7 is a plan view showing a through hole for forming a columnar conductor in an insulating layer molded body.

[Explanation of symbols]

1-divided insulating substrate 1a to 1h, 21a to 21h ... Insulating layer 2 ... Edge electrode 7 ... Recess 8 ... Metal layer 9 ... Column conductor 10 ... Wide part 11 ... Superposed part 17 ... Dividing groove 21 ... Insulating substrate 23 ... Wiring layer 24 ... Via hole conductor 27 ... Punch hole

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/11 H05K 3/40 D 3/00 H01L 23/12 C 3/40 LF term (reference) 5E317 AA22 AA26 BB04 BB12 BB14 CC22 CC25 CD21 CD31 CD32. HH33

Claims (5)

[Claims] 1. An insulating base formed by laminating a plurality of insulating layers made of ceramics, a wiring layer formed between the insulating layers, a via-hole conductor connected to the wiring layer, and a surface formed on the insulating base. It has a dividing groove and a punching hole formed in the thickness direction of the insulating substrate and formed on an extension line of the dividing groove, each of which has a plurality of end face electrodes when the insulating substrate is divided by the dividing groove. A ceramic substrate to be a divided circuit board having, in the thickness direction of each insulating layer, a plurality of columnar conductors partially exposed in the punched hole are formed at predetermined intervals along the punched hole, A ceramic substrate, wherein the columnar conductors of the adjacent upper and lower insulating layers partially overlap each other when viewed from above the insulating substrate, and the overlapping portions of the columnar conductors are exposed in the punched holes. 2. The ceramic substrate according to claim 1, wherein the columnar conductor of the insulating layer has a wide portion whose width gradually increases from an exposed portion inside the punched hole toward the inside of the insulating layer. 3. The ceramic substrate according to claim 1, wherein the columnar conductor of the insulating layer is formed by removing the dividing groove when viewed from above the insulating substrate. 4. A divided circuit board in which an end face electrode is formed in a concave portion formed on the outer peripheral surface of a divided insulating substrate formed by laminating a plurality of ceramic insulating layers and in the thickness direction. The end surface electrode is formed by forming a plurality of columnar conductors partially exposed in the recess along the recess at predetermined intervals in the thickness direction of each of the insulating layers. A divided circuit board, wherein the columnar conductors partially overlap each other when viewed from above the divided insulating substrate, and the overlapped portions of the columnar conductors are exposed in the recesses. 5. The divided circuit board according to claim 4, wherein a metal layer is formed in the recess of the divided insulating substrate.