JPH09205265A - Method for manufacturing ceramic wiring board and green sheet drilling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a hole from being blocked when forming a fine through hole whose a diameter of approximately 50-100μm in a ceramic green sheet in the process for manufacturing a multilayer ceramic wiring board. SOLUTION: When forming a through hole 14a in a ceramic green sheet 14 using a punching pin 12, an ion air current for preventing magnetization is supplied from an ion air current supply blow-off port 19 to the surrounding of a through hole formation site. The through hole 14a thus formed is filled with a conductive paste and at least one ceramic green sheet 14 where the conductive paste is filled is laminated to manufacture a ceramic forming body. By baking the ceramic forming body and simultaneously baking the ceramic base and the conductive paste, a ceramic wiring board is manufactured.

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 ceramic wiring board having through holes filled with conductors, and a green sheet punching device used for the method.

[0002]

2. Description of the Related Art Generally, plastic packages, metal packages, and ceramic packages are used for packaging semiconductor elements such as ICs and LSIs. Of these, the ceramic package has heat dissipation,
It is being widely used as a packaging material for high performance semiconductor devices because it is excellent in terms of electrical characteristics, reliability and the like.

In the ceramic package as described above, it is general to use a multilayer wiring board having through holes as a package base. A multilayer ceramic wiring board is formed by first forming a plurality of ceramic green sheets by the doctor blade method or the like, cutting these sheets into a desired shape, and then passing through the top and bottom of the sheet with a punching device according to the desired wiring pattern. Form a hole. Next, the through holes formed in each sheet are filled with a conductor paste containing a high melting point metal such as W as a main component, and the conductor paste is printed also on the sheet surface according to the wiring pattern. A multilayer ceramic wiring board as a package substrate is obtained by stacking the required number of such ceramic green sheets, stacking them under a constant pressure, press-bonding, degreasing and cofiring the ceramic green sheets and the conductor paste. To be

By the way, with the recent high integration of semiconductor elements and the like, it has been required to increase the density of wiring in the package. Also, the package size is required to be small in order to reduce the mounting area. Therefore, in order to realize a high wiring density in a miniaturized package, miniaturization of through-holes for electrical connection between layers, that is, miniaturization of through-hole diameters has been advanced. Specifically, through holes that have been miniaturized to a diameter of 50 to 100 μm are beginning to be used, but with the miniaturization of such through hole diameters, the problem of frequent clogging during drilling has occurred. . This is the conventional diameter
This is a problem that did not pose a particular problem for through holes of about 200 μm.

That is, the number of through holes depends on the package size, but is about 3000 to 4000 per package, and if even one of them is clogged, it becomes a defective semiconductor package. . The cause of the holes is that the removed sheet scraps attach to the green sheet again. This is because the generated scraps adhere to the pins and die in addition to the clearance control between the pin and the receiving die. It is conceivable that the peelability of the punch residue is deteriorated. Therefore, as a characteristic of the green sheet, measures have been taken such as improving the adhesion to pins and dies, and forcibly eliminating punched dust.

FIG. 3 is a view showing the structure of a conventional punching device which is provided with a measure for preventing punch clogging. As shown in the figure, conventionally, vacuum suction (arrow A), air blowing (arrow B), etc. are performed on the die 1 side. However, since it is not possible to effectively prevent clogging or the like in the miniaturized through hole as described above, in addition to these, air is supplied from the punching pin 2 side to the through hole forming portion of the ceramic green sheet 3 ( Extruding air flow: It is also considered to blow out punched dust from above by making an arrow C). However, even if these measures are taken, it is not possible to completely prevent clogging, and for example, pore clogging occurs at a rate of about 10 to 100 ppm.

Further, regarding the shape of the hole of the through hole, as shown in FIGS. 4 (a) and 4 (b), the degree of the hole of the through hole 4 is often severe, which is incompatible with the miniaturization of the hole diameter. It is also difficult to correct the hole clogging. It should be noted that if the clogging is mild as shown in FIG. 4C, it can be easily corrected by air blowing or the like.

[0008]

As described above, along with the high integration of semiconductor elements and the like, it is necessary to form fine through holes in the ceramic green sheet with a diameter of 50 to 100 μm. However, the conventional perforation device cannot sufficiently prevent the perforation failure such as clogging, resulting in an increase in the failure rate of the green sheet itself and the failure rate in the subsequent manufacturing process of the multilayer ceramic wiring substrate.

As described above, in the conventional manufacturing process of a multilayer ceramic wiring board, the formation of holes or the like is prevented as much as possible when forming through holes having a diameter of about 50 to 100 μm on a ceramic green sheet. That is a challenge.

The present invention has been made to address such a problem, and it is possible to form a fine through hole in a sound and stable manner, thereby suppressing manufacturing defects and reducing manufacturing steps. It is an object of the present invention to provide a method for manufacturing a stabilized ceramic wiring board, and further to provide a green sheet punching device capable of forming finely sized through holes in a sound and stable manner. Has an aim.

[0011]

As a result of studying the cause of clogging of through holes due to punching and the like in order to achieve the above object, the present inventor has found that charging of the green sheet becomes a problem. Here, although the ceramic green sheet is charged with an insulator, the pins and the die are made of metal, so it has been conventionally considered that the pin or the die serves as a ground and the green sheet is not charged. However, in reality, if one pin is used to open more than 100,000 holes, the organic binder and raw material powder contained in the green sheet will adhere to the pins and die, reducing the grounding effect. Resulting in. For these reasons, the green sheet is actually in a state of being easily charged. It has been found that when the green sheet is charged, punch dust or the like is attached due to an electrostatic factor, which is the cause of the clogging of the through hole.

The present invention has been made on the basis of such knowledge, and the method for manufacturing a ceramic wiring substrate of the present invention is
The step of forming a through hole in a ceramic green sheet by using a punching pin, the step of filling a conductor paste into the through hole, and the ceramic green sheet filled with the conductor paste as set forth in claim 1. A method of manufacturing a ceramic wiring board, comprising: a step of producing a ceramic molded body by laminating a plurality of sheets or a plurality of layers; and a step of firing the ceramic molded body to simultaneously sinter the ceramic base material and the conductor paste, It is characterized in that the through hole is formed while blowing an antistatic air flow (ion air flow) around the through hole formation portion of the ceramic green sheet by the punching pin.

The method for manufacturing a ceramic wiring board according to the present invention is particularly effective when the diameter of the through hole is 100 μm or less.

The green sheet punching device of the present invention is a punching device for forming through holes in a ceramic green sheet, as set forth in claim 3.
A punching pin having an outer diameter corresponding to the inner diameter of the through hole, the ceramic green sheet is placed, a die that is a receiving type of the punching pin, and a periphery of a through hole forming portion of the ceramic green sheet by the punching pin. It is characterized by comprising means for supplying an antistatic air flow and a driving mechanism for the punching pin.

According to the present invention, since the antistatic airflow is supplied to the periphery of the through hole forming portion of the ceramic green sheet by the punching pin, it is possible to prevent the ceramic green sheet from being charged when the through hole is formed. Therefore, since it is possible to prevent the sticking of punched dust and the like due to the electrostatic factors described above,
Through holes can be formed soundly and stably without generating holes. Further, the charged green sheet adsorbs fine dust or the like on the surface, which causes a problem at the time of filling the conductor paste in the next step, but by preventing the ceramics green sheet from being charged, in the present invention, the conductor paste filling step is performed. Can be stabilized, and the reliability and electrical characteristics of the obtained inner layer wiring can be improved. By using the ceramic green sheet having such sound through holes, it is possible to stably manufacture a ceramic wiring board having excellent reliability.

[0016]

Embodiments of the present invention will be described below.

An embodiment in which the method for manufacturing a ceramics wiring board of the present invention is applied to the manufacture of a multi-layered ceramics wiring board used as a semiconductor package substrate or the like will be described with reference to the drawings.

First, a plurality of ceramic green sheets are prepared. The ceramic green sheet referred to here is a ceramic raw material powder containing an appropriate amount of a sintering aid, mixed with an appropriate amount of an organic binder and an organic solvent, and formed into a sheet by a known forming method such as a doctor blade method. It is molded.

Next, on each ceramic green sheet,
Through holes are formed according to the inner layer wiring pattern. For forming the through hole, for example, a punching device as shown in FIG. 1 is used. A punching device 11 of which the essential part is shown in FIG. 1 is according to one embodiment of the green sheet punching device of the present invention. The punching device 11 will be described.

The punching device shown in FIG. 1 has a punching pin 1 having an outer diameter corresponding to a desired through hole diameter.
This punching pin 12 is detachably attached to a drive shaft 13 connected to a punching pin drive mechanism (not shown). The drive shaft 13 is provided with an air supply unit 15 for supplying air (extruded air flow: arrow a) to the through hole (14a) forming portion of the ceramic green sheet 14. Further, a rubber cover 16 called a stripper is provided around the punching pin 12, and by applying the rubber cover 16 to the ceramics green sheet 14, the ceramics green sheet 14 is prevented from swaying and moving up and down. ing.

The punching pin 12 is arranged so as to face a die 17 which is a receiving type thereof. The die 17 also serves as a mounting table for the ceramic green sheet 14, and the ceramic green sheet 14 is mounted on the die 17.
The die 17 is connected to a vacuum suction device (not shown) that vacuum-sucks the punched dust (arrow b), and is also provided with an air supply unit 18 for lateral blowing (arrow c). By these vacuum suction and lateral blowing on the die 17 side and the pushing air flow on the punching pin 12 side described above,
The punched residue is forcibly peeled off from the ceramic green sheet 14.

Then, the ceramic green sheet 14
An ion airflow supply outlet 19 for supplying an antistatic ion airflow (arrow d) is installed near the punching pin 12 toward the periphery of the through hole (14a) formation site. The ion air flow supply outlet 19 is connected to an antistatic ion air flow generation source (not shown). The antistatic ion airflow supplied from the ion airflow supply outlet 19 may be a positive or negative ion airflow used for general antistatic. For example, when the distance from the static eliminator is 300 mm, an ion stream with a time of removing static electricity of + 2000V to + 20V for 1 to 2 seconds is used. A commercially available ionizer or the like can be used as a generation source of such an antistatic ion stream.

Further, a similar antistatic ion air flow (arrow e) may be supplied from the air supply unit 15 of the drive shaft 13 or the air supply unit 18 of the die 17.

Using the punching device 11 as described above, while the antistatic ion airflow is blown toward the periphery of the through hole (14a) forming portion of the ceramic green sheet 14, the ceramic green sheet 14 is punched through the through hole with the punching pin 12. 14a is formed. 1
In the case of the hole type punching device (single puncher) 11, generally, one punching pin 12 continuously forms through holes 14a of 100,000 holes or more. At this time, the air supply unit 15 of the drive shaft 13 and the air supply unit 18 of the die 17
It is preferable to simultaneously perform the air supply from the air and the vacuum suction on the die 17 side, and further, to supply the antistatic ion air flow from the air supply unit 15 of the drive shaft 13 and the air supply unit 18 of the die 17. desirable.

As described above, by supplying the antistatic ion current around the through-hole (14a) forming portion of the ceramic green sheet 14, static electricity generated by friction during punching which is continuously performed is eliminated. be able to. Therefore, it is possible to prevent the sticking of punch dust or the like due to the electrostatic force. It is also possible to prevent adsorption of fine dust and the like due to electrostatic force. Therefore, the sound through hole 14a can be stably formed. Further, even if sticking of punching dust occurs, since the ceramic green sheet 14 is prevented from being charged, it becomes mild as shown in FIG. 4 (c) and easily corrected by air blowing or the like. be able to. As a result, the occurrence of defective green sheets due to the clogging of the through holes 14a can be significantly reduced.

The punching device 11 provided with the above-described ion air flow supply outlet 19 is particularly effective for a one-hole punching device in which the ceramic green sheet 14 is likely to be charged by continuous perforation. Further, it is similarly effective for a punching device that continuously punches holes by using several punching pins.

Such a punching device 11 is effective for various ceramic green sheets 14,
For example, it can be applied to green sheets made of various ceramic materials, from oxide-based ceramics such as aluminum oxide to non-oxide-based ceramics such as aluminum nitride and silicon nitride. As described above, although not particularly limited to the material of the ceramic green sheet 14, the glass transition point is low (for example, AlN / T _g =
308K), which is particularly effective for a green sheet in which the sheet temperature easily rises to the vicinity of the glass transition point during punching work. Also, regarding the shape of the through hole 14a, although it is effective for through holes of various shapes, It is especially effective for fine through holes with a diameter (through hole diameter) of 100 μm or less. This is because when the through hole is miniaturized to 100 μm or less, hole clogging is particularly likely to occur as described above.

After forming a large number of through holes in the ceramic green sheet 14 by using the punching device 11 as described above, the conductive paste is filled in each through hole by screen printing or the like. At this time, as described above, since the occurrence of the clogging of the through hole is suppressed as much as possible, the filling process of the conductor paste into the through hole is stabilized, and the occurrence of the clogging of the hole is further prevented. In addition, since adsorption of fine dust and the like due to electrostatic force is also prevented, it is possible to stably and densely fill each through hole with the conductive paste.

Then, a conductor paste is applied to each ceramic green sheet by screen printing or the like according to the inner layer wiring pattern. As the conductor paste, W
A high melting point metal such as Mo or Mo is mixed with an organic binder or an organic solvent to form a paste.

After that, a conductor paste is filled in the through holes, and a plurality of ceramic green sheets having conductor paste printed on the surface thereof are laminated and heated and pressed. The green sheet pressure-bonded body is placed on a firing jig such as a setter and fired in a predetermined gas atmosphere. In this way, by simultaneously firing the ceramic green sheet and the conductor paste, for example, the multilayer ceramic wiring board 20 as shown in FIG. 2 is obtained.

The multilayer ceramic wiring substrate 20 whose main structure is shown in FIG. 2 is a plurality of ceramic layers integrated by firing, for example, four ceramic layers 21a, 21.
Multilayer ceramic substrate 21 having b, 21c and 21d
And an inner layer wiring 22 provided inside the multilayer ceramic substrate 21.

The above-mentioned inner layer wiring 22 has conductor layers 24 filled in through holes 23 provided in the respective ceramic layers 21a to 21d of the multilayer ceramic substrate 21 and conductors formed on the respective ceramic layers 21a to 21d. Layer 2
And 5. The inner layer wiring 22 is formed according to a desired inner layer wiring pattern, and is electrically connected to the connection pads 26 and the electrode pads 27 formed on the front surface side of the multilayer ceramic substrate 21.

Conductor layer 2 filled in through hole 23
4 and the conductor layer 25 formed on each of the ceramic layers 21a to 21d, the conductor paste filled in the through hole 23 and the conductor paste printed on each of the ceramic layers 21a to 21d are printed on the multilayer ceramic substrate 21. It is formed by co-firing with. In the manufacturing process of the multilayer ceramic wiring board 20 as described above, it is possible to prevent the occurrence of defective through holes and to stably perform each process (especially the through hole forming process and the conductor paste filling process). As described above, since the through hole 23 is excellent in hole forming accuracy and hole forming state and the conductor paste can be well filled in the through hole 23, connection failure due to poor filling of the conductor paste or local portion in the through hole 23 is caused. It is also possible to suppress an increase in electric resistance due to a defective filling density. That is, it is possible to obtain the multilayer ceramic wiring board 20 having excellent reliability and electrical characteristics of the inner layer wiring 22 with good reproducibility.

The multilayer ceramic wiring board 2 shown in FIG.
0 is used as a substrate of a semiconductor package such as PGA, BGA, etc., a multilayer wiring board for semiconductor mounting, MC
It can be used as various wiring boards such as an M multilayer wiring board. Further, the present invention is not limited to a flat-plate type multilayer ceramic wiring substrate, and the present invention can be applied to the production of a multilayer ceramic wiring substrate having a cavity, a single-plate type ceramic wiring substrate, and the like. Can be applied to the manufacture of.

[0035]

Next, specific examples of the present invention will be described.

Example 1 First, a plurality of aluminum nitride green sheets were prepared, and through holes were formed in them by using the punching device 11 shown in FIG. The diameter of the formed through holes was 100 μm, and 1 million such through holes were continuously formed (punching / punching). At this time, an ion-balanced antistatic ion stream was supplied from the ion stream supply outlet 19 at a flow rate of 2 to 4 m ³ / min.
Further, the extrusion air flow and the side air flow were supplied from the air supply portion 15 of the drive shaft 13 and the air supply portion 18 of the die 17, and the vacuum suction on the die 17 side was also performed at the same time.

In addition, as a comparative example with the present invention, one million through holes were continuously formed on an aluminum nitride green sheet under the same conditions in the same manner as in Example 1 except that the antistatic ion stream was not supplied. Was formed (Comparative Example 1). Further, the supply of the extrusion airflow from the air supply portion 15 of the drive shaft 13 was stopped, and through holes of 1 million holes were continuously formed on the aluminum nitride green sheet under the same conditions (Comparative Example 2).

The formation state of through holes according to Example 1 and Comparative Examples 1 and 2 was measured and evaluated. Table 1 shows the results.

[0039]

[Table 1] As is clear from Table 1, the hole clogging can be prevented by performing the hole drilling while supplying the antistatic ion stream.
It can be seen that a sound through hole can be formed extremely stably.

Next, with respect to the aluminum nitride green sheet in which the through holes were formed in the above Example 1, filling of the tungsten paste into the through holes and printing on the aluminum nitride green sheet were carried out, and these aluminum nitride sheets were printed. Stack green sheets and then 1
A laminated molded body was produced by pressing at a pressure of 00 kg. This laminated compact is cut into substrate dimensions, degreased in a nitrogen stream, and then fired at 2093K in nitrogen while being placed in a firing jig made of aluminum nitride to simultaneously fire aluminum nitride and tungsten. By doing so, a multilayer aluminum nitride wiring board was obtained. When the wiring condition of the thus obtained multilayer aluminum nitride wiring board was inspected, no wiring was open and the wiring resistance showed a good value.

[0041]

As described above, according to the method for manufacturing a ceramic wiring board of the present invention, since fine through holes can be continuously and soundly and stably formed, the occurrence of manufacturing defects can be suppressed. In addition, it is possible to stabilize the manufacturing process. Also, according to the green sheet punching device of the present invention, it is possible to form finely sized through holes in a sound and stable manner.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part configuration of a green sheet punching device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing the configuration of a multilayer ceramic wiring board manufactured according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a main part configuration of a conventional green sheet punching device.

FIG. 4 is a sectional view showing a form of a hole in a through hole.

[Explanation of symbols]

 11 ... Punching device 12 ... Punching pin 13 ... Drive shaft 14 ... Ceramic green sheet 14a ... Through hole 17 ... Die 19 ... Ion air flow supply outlet 20 ... Multilayer ceramic wiring substrate 21 ... Multilayer ceramic substrate 22 …… Inner layer wiring 23 …… Through hole

Claims (3)

[Claims] 1. A step of forming a through hole in a ceramic green sheet using a punching pin, a step of filling the through hole with a conductor paste, and a step of filling the conductor green paste with the ceramic green sheet
A method for manufacturing a ceramic wiring board, comprising: a step of producing a ceramic molded body by laminating a plurality of sheets or a plurality of layers; and a step of firing the ceramic molded body to simultaneously sinter the ceramic base material and the conductor paste, A method of manufacturing a ceramic wiring board, characterized in that the through hole is formed while blowing an antistatic air flow around a portion of the ceramic green sheet where the through hole is formed by the punching pin. 2. The method for manufacturing a ceramic wiring board according to claim 1, wherein the diameter of the through hole is 100 μm or less. 3. A punching device for forming a through hole in a ceramic green sheet, comprising: a punching pin having an outer diameter corresponding to the inner diameter of the through hole; and the ceramic green sheet being placed on the punching pin. A green sheet perforation, comprising: a die as a mold, a means for supplying an antistatic air flow around the through hole formation portion of the ceramic green sheet by the punching pin, and a driving mechanism for the punching pin. apparatus.