JP2008294337A - Ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic substrate capable of arranging electrode pads thereon with high density and of effectively preventing bad connection from being formed. <P>SOLUTION: A through hole 9A of an outer layer 3 on which electrode pads 6, 7 are formed is formed with its area smaller than a through hole 9B in an adjacent inner layer 4, and the whole of the through hole 9A is opposed to the electrode pads 6, 7. It is hereby possible to prevent a conductive material 10 in the through hole 9A from protruding from the electrode pads 6, 7 so that even when the electrode pads 6, 7 are arranged at high density, bad connection can be effectively prevented. Further, by forming the through hole 9B in the adjacent inner layer 4 with its large area than the through hole 9A of the outer layer 3, even if positions of the through holes 9B in the adjacent inner layers 4 are displaced, no contact of the conductive materials 10 filled in each through hole 9B in the adjacent inner layers 4 can be suppressed, enabling bad contact to be effectively prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic substrate, and more particularly to a ceramic substrate formed by laminating a plurality of ceramic layers and filled with conductive materials that are electrically connected to each other in through holes formed in the respective layers.

  As a substrate constituting various electronic components such as a probe card, a ceramic substrate formed by laminating a plurality of ceramic layers is known. The ceramic substrate is formed by firing a plurality of stacked green sheets, and each green sheet becomes a ceramic layer by firing. A ceramic substrate formed by firing usually includes a pair of outer layers and two or more inner layers sandwiched between the pair of outer layers as ceramic layers.

  As a method of electrically connecting a pair of outer layers of such a ceramic substrate, through holes are formed in each ceramic layer, and the through holes are filled with conductive materials that are electrically connected to each other, thereby thickening the ceramic substrate. A method of forming a through wiring penetrating in the vertical direction is known (for example, Patent Document 1).

  FIG. 3 is a cross-sectional view showing an example of a conventional ceramic substrate 201, and shows a state after firing. As shown in FIG. 3, the fired ceramic substrate 201 includes a pair of outer layers 203 and a plurality of inner layers 204 sandwiched between the pair of outer layers 203, and is formed on each of these ceramic layers 203 and 204. A conductive material 210 is filled in the formed through hole 209.

In this example, a case is shown in which a probe card is constituted by a fired ceramic substrate 201, and electrode pads 206 and 207 are formed on a pair of outer layers 203 of the fired ceramic substrate 201, respectively. On the electrode pad 206 formed on the outer layer 203, a contact probe 205 for contacting the electrode of the semiconductor wafer is attached.
JP 2006-269692 A

  When the area of the through hole 209 formed in each ceramic layer 203, 204 of the ceramic substrate 201 is large, a part of the surface of the conductive material 210 filled in the through hole 209 of the outer layer 203 becomes the electrode pad 206, There is a possibility that the conductive material 210 may be corroded because it protrudes from 207. In addition, with the recent increase in the density of electrodes on a semiconductor wafer, when the contact probes 205 are provided at a high density, the distance between the electrode pads 206 to which the contact probes 205 are attached becomes shorter, so that they protrude from the electrode pads 206. The conductive material 210 may come into contact with the adjacent electrode pad 206, resulting in poor connection.

  However, when the area of the through hole 209 formed in each ceramic layer 203, 204 of the ceramic substrate 201 is reduced in order to solve the above problem, as shown in FIG. When the position of is shifted, the conductive materials 210 filled in the through holes 209 of the adjacent ceramic layers 203 and 204 are not in contact with each other, which may cause a connection failure.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a ceramic substrate in which electrode pads can be arranged at a high density and connection defects can be effectively prevented. .

  The ceramic substrate according to the first aspect of the present invention includes a pair of outer layers and two or more inner layers adjacent to each other sandwiched between the pair of outer layers by laminating a plurality of ceramic layers, and is formed in each layer. A ceramic substrate filled with a conductive material that is electrically connected to each other in the formed through hole, an electrode pad is formed on the surface of one of the outer layers, and the area of the through hole formed in the one outer layer is It is smaller than the area of the through hole formed in each of the inner layers adjacent to each other, and the whole is configured to face the electrode pad.

  According to such a configuration, the area of the through hole in the outer layer where the electrode pad is formed is smaller than the area of the through hole formed in the inner layer adjacent to each other, and the entire area faces the electrode pad. Therefore, it is possible to prevent the conductive material in the through hole from protruding from the electrode pad. Accordingly, even when the electrode pads are arranged at a high density, the conductive material does not protrude from the electrode pads and contact the adjacent electrode pads, so that it is possible to effectively prevent a connection failure from occurring.

  In addition, since the area of the through hole formed in the inner layers adjacent to each other sandwiched between the pair of outer layers is larger than the area of the through hole in the outer layer in which the electrode pad is formed, the penetration between adjacent inner layers Even when the positions of the holes are shifted, it is possible to suppress contact between the conductive materials filled in the respective through holes of the adjacent inner layers. Thereby, it can prevent more effectively that a connection failure arises.

  In addition to the above configuration, the ceramic substrate according to the second aspect of the present invention is used in a probe card having a contact probe, and is configured such that the contact probe is connected to the electrode pad.

  According to such a configuration, the area of the through hole in the outer layer facing the electrode pad to which the contact probe is connected is formed smaller than the area of the through hole formed in the inner layers adjacent to each other. The electrode pads to which the contact probes are connected may be formed with a high density corresponding to each contact probe. In such a case, the distance between adjacent electrode pads must be shortened, Since the electrode pad cannot be formed so large, the conductive material in the through hole easily protrudes from the electrode pad.

  Even in such a case, according to the configuration of the present invention, the area of the through hole in the outer layer facing the electrode pad to which the contact probe is connected is larger than the area of the through hole formed in the adjacent inner layers. Since the whole is opposed to the electrode pad, it is possible to effectively prevent the conductive material in the through hole from protruding from the electrode pad.

  According to the present invention, the area of the through hole in the outer layer in which the electrode pad is formed is smaller than the area of the through hole formed in the inner layer adjacent to each other, and the whole is opposed to the electrode pad. It is possible to prevent the conductive material in the through hole from protruding from the electrode pad, and even when the electrode pads are arranged at a high density, it is possible to effectively prevent poor connection.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing an example of a ceramic substrate 1 according to Embodiment 1 of the present invention. The ceramic substrate 1 is formed by laminating and firing a plurality of green sheets, and each fired green sheet forms a ceramic layer 2. The fired ceramic substrate 1 is provided with a pair of outer layers 3 as ceramic layers 2 and two or more inner layers 4 sandwiched between the pair of outer layers 3.

  In the present embodiment, the fired ceramic substrate 1 is used for a probe card having a contact probe 5. In the first outer layer 3A and the second outer layer 3B constituting the pair of outer layers 3 of the ceramic substrate 1, a plurality of electrode pads 6 and 7 are formed on the surface opposite to the inner layer 4, that is, the surface 3C. The A contact probe 5 for contacting an electrode of a semiconductor wafer as an inspection object is attached to each electrode pad 6 formed on the first outer layer 3A.

  Each electrode pad 6 to which the contact probe 5 is attached is connected to an electrode pad 7 formed on the second outer layer 3 </ b> B via a through wiring 8 formed in the ceramic substrate 1. Each electrode pad 7 formed on the second outer layer 3B is a tester device (not shown) for inspecting the electrical characteristics of the integrated circuit formed on the semiconductor wafer via the main substrate holding the ceramic substrate 1. Connected).

  The through wiring 8 formed in the ceramic substrate 1 is formed by electrically connecting conductive materials 10 filled in through holes 9 called via holes formed in each ceramic layer 2. Since the ceramic layer 2 is more fragile than the green sheet, each through hole 9 is formed in each green sheet before firing, and after filling each through hole 9 with the conductive material 10 and laminating each green sheet, The ceramic substrate 1 is formed in such a manner that it is fired. For example, a silver palladium alloy is used as the conductive material 10.

  Of each through hole 9, the through hole 9A formed in the outer layer 3 is formed to have an area smaller than that of the corresponding electrode pad 6, 7, and the entire through hole 9A is formed on the corresponding electrode pad 6, 7. Opposite. On the other hand, the through-hole 9B formed in the inner layer 4 among the through-holes 9 is larger in area than the through-hole 9A formed in each outer layer 3, and the through-hole 9B formed in the adjacent inner layer 4 It faces at least a part of. Further, the entire through hole 9 </ b> A formed in the outer layer 3 is opposed to the through hole 9 </ b> B formed in the inner layer 4 adjacent to the outer layer 3.

  In this example, the through holes 9A of the outer layers 3 are formed in the same shape, and the through holes 9B of the inner layers 4 are formed in the same shape. The area of the through hole 9B formed in each inner layer 4 may be smaller or larger than the area of the electrode pads 6 and 7.

  In the present embodiment, the area of the through-hole 9A in the outer layer 3 where the electrode pads 6 and 7 are formed is smaller than the area of the through-hole 9B formed in the inner layer 4 adjacent to each other, and the entirety is the electrode pad. 6 and 7, the conductive material 10 in the through hole 9A can be prevented from protruding from the electrode pads 6 and 7. As a result, even when the electrode pads 6 and 7 are arranged at a high density, the conductive material 10 does not protrude from the electrode pads 6 and 7 and contact the adjacent electrode pads 6 and 7. It can be effectively prevented from occurring.

  The area of the through hole 9B formed in the adjacent inner layer 4 sandwiched between the pair of outer layers 3 is larger than the area of the through hole 9A in the outer layer 3 where the electrode pads 6 and 7 are formed. Therefore, even if the positions of the through holes 9B between the adjacent inner layers 4 are shifted, it is possible to prevent the conductive materials 10 filled in the respective through holes 9B of the adjacent inner layers 4 from coming into contact with each other. . Thereby, it can prevent more effectively that a connection failure arises.

  In particular, in the present embodiment, the area of the through hole 9A in the outer layer 3 facing the electrode pad 6 to which the contact probe 5 is connected is formed smaller than the area of the through hole 9B formed in the inner layer 4 adjacent to each other. Has been. The electrode pads 6 to which the contact probes 5 are connected may be formed with a high density corresponding to each contact probe 5. In such a case, the distance between the adjacent electrode pads 6 must be shortened. In addition, since each electrode pad 6 cannot be formed so large, the conductive material 10 in the through hole 9 </ b> A can easily protrude from the electrode pad 6.

  Even in such a case, in the present embodiment, the area of the through hole 9A of the outer layer 3 facing the electrode pad 6 to which the contact probe 5 is connected is a through hole formed in the inner layer 4 adjacent to each other. Since the entire area is smaller than the area of 9B and faces the electrode pad 6, it is possible to effectively prevent the conductive material 10 in the through hole 9A from protruding from the electrode pad 6.

  The positions where the electrode pads 6 and 7 and the contact probes 5 are attached to the outer layer 3 are determined in advance. For example, the attachment positions of the electrode pads 6 and the contact probes 5 with respect to the first outer layer 3A are predetermined according to the positions of the electrodes on the semiconductor wafer. The attachment positions of the electrode pads 7 with respect to the second outer layer 3B are determined in advance according to the positions of the connection terminals formed on the main substrate connected to the electrode pads 7.

  However, after forming the through holes 9 in each green sheet before firing, when the ceramic substrate 1 is formed by laminating and firing the green sheets, the green sheets shrink during firing, The position of the through hole 9 formed in the ceramic layer 2 is shifted with respect to the through hole 9 formed in the green sheet before firing. Therefore, when each electrode pad 6, 7 and each contact probe 5 are attached at a predetermined attachment position, the conductive material 10 filled in the through hole 9 </ b> A of the outer layer 3 is formed on the electrode pad formed in the outer layer 3. There is a high possibility of protruding from 6 and 7.

  In the present embodiment, since the area of the through hole 9A of the outer layer 3 on which the electrode pads 6 and 7 are formed is relatively small, the position of the through hole 9A is slightly shifted due to shrinkage during firing. However, it is possible to prevent a part of the through hole 9A from facing the electrode pads 6 and 7 and to effectively prevent the conductive material 10 in the through hole 9A from protruding from the electrode pads 6 and 7.

Embodiment 2. FIG.
In the first embodiment, the configuration in which the through holes 9B of all the inner layers 4 sandwiched between the pair of outer layers 3 are formed in the same shape as each other has been described. On the other hand, in the second embodiment, the through holes 9B of some inner layers 4 are formed in a shape different from the through holes 9B of other inner layers 4 adjacent to the inner layer 4.

  FIG. 2 is a sectional view showing an example of the ceramic substrate 101 according to the second embodiment of the present invention. This embodiment has the same configuration as the ceramic substrate 1 of the first embodiment except that the shapes of the through holes 9B of some of the inner layers 4 are different. The same reference numerals are assigned and description thereof is omitted.

  In this ceramic substrate 101, through holes 9B in some inner layers 4A among inner layers 4 sandwiched between a pair of outer layers 3 are formed in a shape different from through holes 9B in other inner layers 4B. In this example, the through holes 9B of some inner layers 4A are formed in the same shape as the through holes 9A of the outer layer 3, so that they are smaller than the through holes 9B of other inner layers 4B. The through holes 9B of the other inner layer 4B are formed in the same shape. However, the through holes 9B of the partial inner layer 4A are not limited to the configuration formed in the same shape as the through holes 9A of the outer layer 3, and may be larger than the through holes 9A of the outer layer 3. The shape may be small.

  Thus, even if the shape of the through holes 9B of some inner layers 4A among the inner layers 4 sandwiched between a pair of outer layers 3 is different from the shape of the through holes 9B of other inner layers 4B, As in the example of FIG. 2, if the area of the through hole 9B formed in each of the adjacent inner layers 4B included in the other inner layer 4B is larger than the area of the through hole 9A of the outer layer 3, In addition, poor connection between the conductive materials 10 filled in the through holes 9B of the adjacent inner layers 4 can be suppressed.

  If the through holes 9B of some inner layers 4A are formed with a smaller area than the through holes 9B of other inner layers 4B as in the present embodiment, the amount of the conductive material 10 filled in the through holes 9B is reduced. Therefore, as compared with the configuration in which the through holes 9B of all the inner layers 4 are formed in the same shape as in the first embodiment, the manufacturing cost can be reduced.

  In the above embodiment, the case where the area of each through hole 9A of the pair of outer layers 3 is smaller than the area of the through hole 9B of the inner layer 4 is described. However, the present invention is not limited to this configuration, and the first outer layer 3A. Alternatively, the configuration may be such that only the through hole 9A formed in one of the second outer layers 3B is formed with an area smaller than the area of the through hole 9B of the inner layer 4.

  Moreover, although the above embodiment demonstrated the case where the ceramic substrates 1 and 101 were used for a probe card, the ceramic substrate of this invention is applicable to various electronic components other than a probe card.

FIG. 1 is a cross-sectional view showing an example of a ceramic substrate according to Embodiment 1 of the present invention. It is sectional drawing which showed an example of the ceramic substrate by Embodiment 2 of this invention. It is sectional drawing which showed an example of the conventional ceramic substrate, and has shown the state after baking.

Explanation of symbols

1,101 Ceramic substrate 2 Ceramic layer 3 Outer layer 4 Inner layer 5 Contact probe 6, 7 Electrode pad 9 Through hole 10 Conductive material

Claims (2)

A conductive material having a pair of outer layers and two or more adjacent inner layers sandwiched between the pair of outer layers by laminating a plurality of ceramic layers, and conducting to each other in a through hole formed in each layer Is a ceramic substrate filled with
An electrode pad is formed on the surface of one of the outer layers,
The through-hole formed in the one outer layer has an area smaller than the area of the through-hole formed in each of the inner layers adjacent to each other, and is entirely opposed to the electrode pad. Characteristic ceramic substrate. The ceramic substrate is used for a probe card having a contact probe,
The ceramic substrate according to claim 1, wherein the contact probe is connected to the electrode pad.

Images