JP2003046241A - Circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board which resists warp of especially a printed wiring board by improving a structure of an edge of a circuit board. SOLUTION: A circuit board 10 comprises a lamination body 1 wherein a plurality of insulation layers formed of a ceramic material are laminated, an inner wiring conductor 2 disposed between insulation layers of the lamination body 1, a surface layer wiring conductor 4 disposed in a main surface of the lamination body 1, and a circuit mounting component 6 disposed in the surface layer wiring conductor 4. A tilting surface 7 forming an angle θ1 of 110 to 145 deg. with a side surface is formed in a ridge line part of at least one main surface of the lamination body 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated body in which a plurality of insulating layers made of a ceramic material are laminated, an internal wiring conductor arranged between insulating phases of the laminated body, and a front surface and a back surface of the laminated body. The present invention relates to a ceramic circuit board including a surface layer wiring conductor.

[0002]

2. Description of the Related Art Conventionally, ceramic circuit boards have been studied as circuit boards used in electric and electronic devices.
Further, in recent years, ceramic circuit boards have been used in high frequency circuit fields by utilizing the excellent reliability and electrical characteristics of ceramics.
In particular, many studies have been conducted for use in RF modules such as power amplifiers and filters used in mobile phones and the like.

When low-temperature fired ceramics that can be fired at 800 ° C. to 1200 ° C. are used as the substrate material, a low resistance material such as Ag or Cu can be used for the wiring.

Examples of the ceramic material include alumina, cristobalite, and quartz. In recent years, since a capacitance component and a reactance component are contained inside the ceramic substrate, a dielectric material such as titanium oxide, magnesium titanate, calcium titanate, or the like is used. Materials using a mixture may be used.

The low-temperature fired ceramic material is mainly glass-ceramic, and for example, cordierite,
A low melting point glass component capable of precipitating at least one of crystal phases such as mullite, anorthite, sergian, spinel, garnite, willemite, dolomite, betalite, osumilite and its substituted derivatives, and cristobalite, quartz, alumina, titanium oxide. , And a ceramic material such as magnesium titanate (an inorganic filler).

The internal wiring conductor and the surface wiring conductor material include
When using the above-mentioned low temperature fired ceramic material, a low resistance conductor containing silver or copper as a main component is used.

In this way, the internal wiring conductor is arranged inside the laminated body in which the insulating layers of the low temperature fired ceramic material are laminated, the surface wiring conductor is formed on the main surface of the laminated body, and the surface wiring conductor has a predetermined shape. The circuit board on which the circuit parts are arranged is a high-frequency circuit that oscillates a signal of a predetermined oscillation frequency of a mobile phone,
Alternatively, it is handled as one component of a module that integrates complex functions. Specifically, this circuit board has come to be soldered to a printed wiring board for use.

[0008]

However, in a mobile terminal such as a mobile phone, when it is mounted on a printed wiring board and a flexure experiment of the printed wiring board is performed, the circuit board from the starting point 13 of the ridge line portion to the circuit board as shown in FIG. A crack will occur from the ridge.

This is because a low resistance material such as Ag or Cu is used for the internal wiring conductor, and therefore a glass-ceramic material is used. There is. Further, in the future, with the progress of thinner substrates, cracks are more likely to occur due to bending.

The present invention has been devised in view of the above-mentioned problems, and an object thereof is to improve a structure of an edge portion of a circuit board, and in particular, to provide a circuit board which can endure the bending of a printed wiring board. It is provided.

[0011]

According to the present invention, a laminated body in which a plurality of insulating layers made of a ceramic material are laminated, an internal wiring conductor arranged between the insulating layers of the laminated body, and a main surface of the laminated body are arranged. In a circuit board comprising the surface layer wiring conductor formed as described above and a circuit mounting component arranged on the surface layer wiring conductor, the ridgeline portion of at least one main surface of the laminate has an angle θ1 formed with the side surface of 110 to 145 °. An inclined surface is formed.

The ceramic material is 800 to 1200 ° C.
It is a low temperature fired ceramic that can be fired at.

Further, at the ridge line between the inclined surface and the side surface of the laminate, the angle between the side surface and the side surface is 160 to 175.
A second inclined surface having a surface angle of 90 ° is formed.

Further, the distance from the surface of the laminated body to the ridgeline portion between the second inclined surface and the side surface of the laminated body is 30% or less of the thickness of the laminated body.

According to the circuit board of the present invention, the ridgeline portion of at least one main surface of the laminate has an angle .theta.1 of 11 with the side surface.
An inclined surface of 0 to 145 ° is formed.

Therefore, even when the printed wiring board is mounted and is bent, the stress is dispersed due to the inclined surface at the ridge portion, and as a result, cracks are effectively generated at the ridge portion of the circuit board. Can be prevented. Moreover, 800-1
No crack is generated even with a low temperature fired ceramic material (glass-ceramic material) that can be fired at 200 ° C.

When the angle θ1 of the inclined surface is less than 110 °, the portion where the inclined surface intersects the main surface is on the center side of the substrate, so that the mounting area of the mounted circuit components is reduced and the high-density mounting property is improved. Will fall. In addition, the angle θ1 of the inclined surface is 14
When it exceeds 5 °, the angle formed by the inclined surface and the main surface comes close to 90 °, and as a result, even if the printed wiring board is bent, the effect of dispersing the flexural stress is reduced and cracks occur. Will occur.

When the angle θ1 of the inclined surface becomes small,
The distance becomes smaller from the main surface of the laminated body to the portion where the inclined surface and the side surface intersect. As a result, when each circuit board is extracted by a division process on a large circuit board, the divisibility is deteriorated. Therefore, by further forming a second inclined surface having an inclination angle of 5 to 20 at the intersection of the inclined surface and the side surface, the divisibility from the large-sized circuit board is improved. However, if the portion where the side surface of the laminated body and the second inclined surface intersect is too deep from the main surface of the laminated body, it will be inadvertently cut before the dividing process, so that the thickness is relative to the thickness of the laminated body. It is preferably less than 30%. This improves the splittability.

[0018]

DETAILED DESCRIPTION OF THE INVENTION A circuit board of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a circuit board according to the present invention. FIG. 2 is a perspective view of a large-sized circuit board having a dividing groove according to the present invention.

Reference numeral 10 is a circuit board, 1 is a laminated board, and 2 is a laminated board.
Is an internal wiring conductor formed in the laminated substrate 1, 3 is a via hole conductor formed in the laminated substrate 1, 4 is a surface wiring conductor formed on the surface of the laminated substrate 1, 5 is an IC chip component, and 6 is Another circuit mounting component, 7 is an inclined surface.

The laminated substrate 1 includes insulating layers 1a to 1d made of a ceramic material and layers between the insulating layers 1a to 1d.
Internal wiring conductors 2 are arranged, which are predetermined wiring patterns, capacitor capacitance electrodes, coil inductor patterns, strip line patterns, and the like. Insulator layers 1a-1d
A via-hole conductor 3 is formed in the through hole 3 in the thickness direction.

Further, a surface wiring conductor 4 is formed on the main surface of the laminated substrate 1. And this surface wiring conductor 4
An IC chip component 5 and a circuit mounting component 6 are mounted on the.

The insulating layers 1a to 1d are, for example, 800 to 1.
It is made of a glass-ceramic material that enables firing at relatively low temperatures around 200 ° C. Specific ceramic materials include insulating ceramic materials such as cristobalite, quartz, corundum (α-alumina), mullite, cordierite, MgTiO ₃ , CaTiO ₃ , BaTiO ₃ , and T.
dielectric ceramic material, such as iO _2, Ni-Zn ferrite, magnetic ceramic material such as Mn-Zn ferrite (referred to ceramic in a broad sense) can be mentioned. The average particle size is 0.5 to 6.0 μm, preferably 0.5 to 2.0 μm. Also,
Two or more kinds of ceramic materials may be mixed and used.

The glass component frit can be obtained by subjecting it to firing treatment to obtain cordierite, mullite, anorthite,
Sergian, spinel, garnite, willemite, dolomite, petalite or any derivative thereof as long as it precipitates a crystal phase or crystal phase of spinel structure, for example,
Examples thereof include glass frits containing B ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , ZnO and alkaline earth oxides. Such a glass frit has a wide vitrification range and a yield point of 600.
The temperature is around 800 ° C. These insulator layers 1a-1d
Has a thickness of, for example, about 20 to 300 μm.

The internal wiring conductor 2 and the via-hole conductor 3 are A
The internal wiring conductor 2 has a thickness of about 5 to 25 μm, which is made of a conductor film (conductor) whose main component is g-based (Ag simple substance, Ag alloy such as Ag—Pd, Ag—Pt). The diameter of the via-hole conductor 3 can be set to any value, but is set to 50 to 300 μm depending on the thickness of the insulating layer. However, depending on the ceramic material, Cu-based, W-based, Mo
A system, a Pd system, etc. may be used.

The surface wiring conductor 4 is made of Ag (Ag alone, A
A circuit mounting component 6 (which is composed of a conductor film containing Ag alloy such as g-Pd or Ag-Pt as a main component) and mainly constitutes a predetermined circuit wiring on the surface of the laminated substrate 1 and is joined via solder. For example, it may be a circuit component, a transistor, or the like, and may be a connection pad of the surface layer wiring conductor 4 connected to the surface wiring conductor 4 via solder), or a terminal electrode of a thick film resistance film or a thick film capacitor element. In particular, in the connection with the internal wiring conductor 2, the surface wiring conductor 4 is the insulator layer 1a.
It is connected to the via-hole conductor 3 exposed from.

The IC chip 5 is connected to the surface wiring conductor 4 via a bump member of Al or Au formed on the lower surface of the IC chip 5. Further, there may be a connection by wire bonding depending on the case.

Next, a method of manufacturing the circuit board 10 will be described.

First, a large green sheet to be the insulating layers 1a to 1d of the laminated body 1, an internal wiring conductor 2, an Ag-based conductive paste for forming the via-hole conductor 3, and a surface wiring conductor 4 are formed. For eg Au system, A
A g-based conductive paste is prepared.

The green sheet has a plurality of circuit board regions so that a plurality of circuit boards can be extracted, and is made of a ceramic material. For example, ceramic powder,
A slurry in which a frit of a low melting point glass component, an organic binder, and an organic solvent are homogeneously kneaded is formed into a sheet with a predetermined thickness by a doctor blade method and cut into a predetermined size to form a sheet.

The composition ratio of the above-mentioned ceramic material and glass material is such that the ceramic material is 10 to 98 wt%, preferably 45 to 95 wt% for firing at a relatively low temperature of 800 to 1200 ° C., for example. Is 2-9
It is 0 wt%, preferably 5-55 wt%.

It is necessary to give importance to the wettability of the organic binder with the solid content (ceramic powder, frit of a low melting point glass component), and the organic binder is thermally decomposable so that it can be burned out at a relatively low temperature and in a short firing process. An excellent one is preferable, and an ethylenically unsaturated compound having a carboxyl group or an alcoholic hydroxyl group such as an acrylic acid or methacrylic acid polymer is preferable.

As the solvent, an organic solvent or an aqueous solvent can be used. For example, in the case of an organic solvent, 2,
For example, 2,4-trimethyl-1,3-pentadiol monoisobentate is used, and in the case of an aqueous solvent, it needs to be water-soluble, and a monomer and a binder have hydrophilic functional groups such as carboxyl. A group is added.

The amount of addition is 2 to 300, preferably 5 to 100 when expressed in terms of acid value. If the amount added is small, the solubility in water and the dispersibility of the powder of the fixed component will deteriorate,
When the amount is large, the thermal decomposability becomes poor. Therefore, the addition amount is appropriately added within the above range in consideration of solubility in water, dispersibility, and thermal decomposability.

Next, a through hole to be the via-hole conductor 3 is formed by punching in each circuit board region of the green sheet to be the insulating layers 1a to 1d. At the same time, a conductor to be the via-hole conductor 3 is formed in the through hole by printing / filling Ag-based conductive paste, and in particular, a conductor to be the internal wiring conductor 2 is formed on the green sheet to be the insulating layers 1b to 1d. The film is formed by printing and drying Ag-based conductive paste. In addition, a conductor film to be the surface wiring conductor 4 is formed on the green sheet to be the insulator layer 1a by Ag.
It is formed by printing and drying a conductive paste.

Here, the Ag-based conductive paste of the via-hole conductor 3 and the internal wiring conductor 2 is Ag-based (Ag simple substance, Ag
-Ag alloy such as -Pd) powder, borosilicate low-melting glass frit, organic binder such as ethyl cellulose, and a homogeneous mixture of solvents are used.

The Ag-based conductive paste for the surface wiring conductor 4 is a homogeneous mixture of Ag-based (Ag simple substance, Ag alloy such as Ag-Pd) powder, Pt powder, low melting point glass frit, organic binder, and solvent. Is used.

Next, a via-hole conductor 3 is formed in each circuit board area.
A green sheet serving as an insulator layer 1b to 1d having a conductor film serving as an internal wiring conductor 2 and a green sheet serving as an insulator layer 1a having a conductor film serving as a surface wiring conductor 4 are laminated. A large-sized circuit board is formed by stacking layers in order and integrating them by pressure bonding or the like at a predetermined pressure.

Next, FIG. 2 shows a large-sized circuit board in an unfired state. Dividing groove 8 so as to partition each circuit board region 10 '
To form.

The characteristic inclined surface 7 of the present invention is preferably formed in the step of forming the dividing groove 8. That is, the V-shaped inclined surface of the dividing groove 8 becomes the inclined surface 7 of the circuit board 10. That is, when forming the dividing groove 8, a notch is formed by dicing or a cutter blade that can form an inclined surface.

FIG. 3 is a perspective view in a sectional state so that the inclined surface 7 can be understood as the dividing groove 8. In addition, FIG.
Another inclined surface 9 is formed at the intersection of the inclined surface 7 and the side surface of the laminated body 1 so that the large-sized circuit board 11 shown in FIG. 2 can be easily divided along the dividing groove 8.

Next, the unfired large circuit board is subjected to simultaneous firing treatment in an oxidizing atmosphere or an air atmosphere. In addition,
This firing process includes a binder removal process and a sintering process.

In the binder removal process, the insulating layers 1a to 1d are used.
Green sheet, which will become the internal wiring conductor 2, conductor film,
This is for burning out the organic components contained in the conductor to be the via-hole conductor 3 and the conductor film to be the surface wiring conductor 4, and is performed in a temperature range of 500 to 600 ° C., for example.

In the sintering process, the glass component of the glass-ceramic green sheet is crystallized and, at the same time, it is uniformly dispersed in the grain boundaries of the ceramic powder to give the laminated body a certain strength to form the internal wiring conductor 2. The conductor film, the conductor to be the via-hole conductor 3, and the metal powder and Ag powder of the conductive material of the conductor film to be the surface wiring conductor 4 are grain-grown to reduce the resistance and are integrated with the insulator layers 1a to 1d. is there. This is done until a peak temperature of 800-1200 ° C is reached.

As a result, a large-sized circuit board in which the internal wiring conductor 2 and the via-hole conductor 3 are formed inside each circuit board region and the surface wiring conductor 4 is formed on the surface is achieved.

Next, various electronic components 6 connected to the surface wiring conductor 4 are joined and mounted by soldering or the like.

Finally, a dividing process is performed along the dividing groove 8 that divides each circuit board. As a result, the large circuit board 11
From this, a plurality of circuit boards 10 shown in FIG. 1 will be extracted. Thus, according to the circuit board 10 of the present invention,
An inclined surface 7 is formed on at least a main surface of the laminated body 1, for example, a ridge portion formed by a surface and a side surface of the laminated body 1. Moreover, the inclined surface 7 and the side surface of the laminated body 1 (shown by the dotted line in FIG. 3)
The inclination angle θ1 formed by is 100 to 145 °.
That is, the angle θ2 formed by the main surface of the laminated body 1 and the inclined surface 7 is 12
It becomes 5 to 160 °.

As a result, even if this circuit board 10 is mounted on a printed wiring board, and then flexural stress is applied to the printed wiring board, no cracking or the like occurs at the ridge portion of the laminated body 1 of the circuit board 10. This is because the inclined surface 7 is formed at the ridge portion of the laminated body 1 of the circuit board 10 on which the flexural stress is likely to be concentrated, and the angles θ1 and θ2 are obtuse angles, and the angles are distributed to these two corner portions. It is thought to be because. As a result, the glass having a relatively low substrate strength
Even in the laminated body 1 made of a ceramic material, cracks do not occur.

Further, by properly setting the angle θ1 of the inclined surface 7, it is possible to effectively prevent the crack due to the flexural stress described above, and the angle θ1 of the inclined surface 7 becomes small, so that the inclined surface 7 and the main surface of the laminated body 1 are inclined. It is possible to prevent the region where the surface 7 intersects from being located too close to the center of the laminated body 1 and narrowing the mounting region of the IC chip 5 and the circuit mounting component 6.

[0049]

EXAMPLES Next, the present invention will be described based on examples.

The present inventor manufactured the circuit board 10 by the above manufacturing method. The size of the laminated body 1 after firing is 750 μm as a whole by laminating five insulating layers having a thickness of 150 μm after firing. The size of the circuit board is 15 x 8 mm, and the size of the large circuit board is 75 x
The inner wiring conductor 2 and the surface wiring conductor 4 had a thickness of 64 μm, and the via-hole conductor 3 was formed in a cylindrical shape having a diameter of 150 μm inside the substrate. As the conductor at this time, an Ag-based conductor was used. Then, after forming the large-sized circuit board, the inclined surface 7 was formed by cutting or pushing with a dicing or a cutter blade. The angle (angle formed with the side surface of the laminated body 1) θ1 of the inclined surface 7 is 110 to 145 ° (when there is no inclined surface, the inclination angle θ1 is 180 degrees) and the depth is 30 to.
Grooves were formed so as to be cut by 300 μm. Next, the large-sized circuit board in an unbaked state is subjected to simultaneous baking treatment in an air atmosphere at a peak temperature of 900 ° C., and the baked large-sized circuit board is divided into each circuit board at a portion cut by a dicing or cutter blade. To form the inclined surface 7.

The present inventor has determined that the tilt angle θ1 is 180
°, 150 °, 145 °, 135 °, 110 °, 100
The circuit board 10 is set to 100 mm × 40 mm ×
It was mounted on the center of a 1.6 mm mother board, and this mother board was bent. And the circuit board 10
The amount of deflection (limit value) in the thickness direction of the mother board in which a crack was generated at the ridge portion of the laminated body 1 was measured.

Further, the degree of mounting exclusiveness of the IC chip 5 and the circuit mounting component 6 which can be mounted on the circuit board 10 was examined. The results are shown by ○ and ×. It should be noted that ◯ is good, and x is bad, and as a judgment of the failure, an unmountable region of the circuit mounting component 6 which is three times or more the depth of the inclined surface 7 occurs in the central direction of the laminated substrate 1. I decided. The results are shown in Table 1.

[0053]

[Table 1]

In the table, in the present embodiment, the flexural strength is improved by 5% or more and the allowable flexure exceeds 2.0 mm in comparison with the circuit board having the conventional structure.
The IC chip 5 and the circuit mounting components 6 can be mounted on the laminated body 1 at high density.

Further, although the angle θ1 formed by the side surface of the laminated body 1 and the inclined surface 7 becomes small, the allowable deflection amount becomes large, but
The intersection of the main surface of the laminated body 1 and the inclined surface 7 is located closer to the center of the laminated body 1 and presses the mounting portion of the circuit mounting component 6. Therefore, the intersection of the main surface of the laminated body 1 and the inclined surface 7 is not located closer to the center of the laminated body 1, and in order to maintain the allowable deflection amount, as shown in FIG.
At the intersection of the side surface of the laminate 1 and the inclined surface 7, a second
It is desirable to form the inclined surface 9 of. At this time, the angle θ3 formed by the second inclined surface 9 and the side surface of the laminated body 1 is 160 to 1
Set in the range of 75 °. As a result, the intersection of the side surface of the laminated body 1 and the second inclined surface 9 becomes a direction away from the main surface of the laminated body 1. That is, it means that the depth of the dividing groove 8 becomes deep. When the dividing groove 8 becomes deeper in this way, as shown in FIG.
It is conceivable that, in the state of the large-sized circuit board 11 shown in FIG. 2, abrupt division occurs in the division groove 8 before the regular division processing step, which lowers the production efficiency of the manufacturing process. For this reason,
From the main surface of the laminated body 1, the side surface of the laminated body 1 and the second inclined surface 9
The distance to the intersection with is 3 with respect to the thickness of the laminate 1.
It is important to make it less than 0%. As shown in FIG. 1, when the inclined surface 7 and the second inclined surface are formed from both main surface sides of the laminated body 1, the distance to the deepest position of each dividing groove 8 is 30%. It is important that at least 40% or more of the thickness of the laminated body 1 is left as the connecting portion of the adjacent circuit component region 10 '.

In the above embodiment, the main surface of the laminated body 1
For example, the measurement was performed by forming the inclined surface only on the ridgeline portion of the surface, but as shown in FIG. 1, the inclined surface may be formed on the ridgeline portions of both main surfaces of the surface and the bottom surface.

[0057]

As described above, the inclined surface is formed at the intersection of at least one of the front surface and the back surface of the ceramic circuit board and the end surface of the ceramic circuit board. Even if flexural stress is generated, a large stress is not concentrated and applied to the ridge portion, and the strength of the circuit board can be improved. In addition, the circuit board can be mounted with high density without pressing the mounting area of the circuit mounting components mounted on the circuit board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a circuit board according to the present invention.

FIG. 2 is a perspective view of a large circuit board for obtaining the circuit board according to the present invention.

FIG. 3 is a perspective view showing a partial cross section of a circuit board according to the present invention.

FIG. 4 is a perspective view showing a partial cross section of a third embodiment according to the present invention.

FIG. 5 is a schematic diagram showing a crack generation situation due to a flexural stress in a conventional circuit board.

[Explanation of symbols]

10 circuit board 1 Laminated board 1a-1d insulator layer 2 Internal wiring conductor 3 Via hole conductor 4 Surface wiring conductor 5 IC chip 6 electronic components 7 slope 8 split grooves 9 Second slope

Claims (4)

[Claims] 1. A laminated body in which a plurality of insulating layers made of a ceramic material are laminated, an internal wiring conductor arranged between insulating layers of the laminated body, a surface wiring conductor arranged on a main surface of the laminated body, In a circuit board including a circuit mounting component arranged on a surface wiring conductor, an inclined surface whose angle formed by the side surface is inclined at 110 to 145 ° is formed at a ridge portion of at least one main surface of the laminate. A circuit board characterized by the above. 2. The ceramic material is 800-1200.
The circuit board according to claim 1, which is a glass-ceramic material that can be fired at a temperature of ℃. 3. A second sloped surface is formed at the intersection of the sloped surface and the side surface of the laminated body, the second sloped surface further forming an angle of 160 to 175 ° with the side surface. The circuit board according to item 1. 4. The distance from the surface of the laminated body to the ridge portion between the second inclined surface and the side surface of the laminated body is 30% or less of the thickness of the laminated body. The described circuit board.