JPH0722752A - Multilayer ceramic substrate and its manufacture - Google Patents

Abstract

PURPOSE:To facilitate surface layer wiring simultaneously with inner-layer baking in the manufacture of a multilayer ceramic substrate. CONSTITUTION:In a roll-shaped film, a substrate constitution sheet 1 is formed and the substrate constitution sheet 1 is drilled and then a conductor paste 4 is buried into the hole. Then, after a conductor pattern 5 is formed, the substrate constitution sheet 1 is peeled and cut from the roll, the substrate constitution sheet 1 which becomes the lowest layer is inverted so that the surface side of the conductor pattern 5 becomes the surface, and then the substrate constitution sheet 1 is laminated on it without inversion. Further, the method for manufacturing a multilayer ceramic substrate consists of a process for laminating a plurality of substrate constitution sheets 1 without conversion successively and a process for baking the laminated multilayer sheet, thus baking the inner layer and surface layer patterns simultaneously and easily.

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 multi-layer ceramic substrate for mounting semiconductor LSIs, chip parts, etc. and interconnecting them.

[0002]

2. Description of the Related Art In recent years, a multilayer ceramic substrate has been required to have a high density with the rapid expansion of devices. Further, with the digitization of circuits, the number of pins is increasing, the pitch is narrowing, the mounting form is surface mounting, and further the flip chip mounting is progressing.

However, the multilayer ceramic substrate has the following problems. That is, it is necessary to form the surface layer wiring after firing the inner layer wiring. This is because shrinkage due to sintering occurs during firing, and the shrinkage due to sintering varies depending on the substrate material used, the green sheet composition, the powder lot, etc. If the contraction error is large, the inner layer electrode cannot be connected due to the dimensional error with the surface wiring pattern. As a result, a land having an unnecessarily large area must be formed in the surface layer electrode portion so as to allow a shrinkage error in advance, and it cannot be used in a circuit that requires high-density wiring. In addition, a method is used in which some screen plates for surface wiring are prepared according to the shrinkage error and are used according to the shrinkage rate of the substrate. This method is uneconomical because many screen versions must be prepared.

Further, in the solder paste printing at the time of mounting the last component, there may be a case where the necessary portion cannot be printed due to an error in the shrinkage ratio. Also, when mounting components, there is a deviation from the predetermined component position. In order to reduce these shrinkage errors as much as possible, in the manufacturing process, not only the management of the substrate material and the green sheet (hereinafter referred to as the substrate composition) composition, but also the difference in the powder lot and the lamination conditions (press pressure, temperature) are sufficiently controlled. There is a need to. However, it is generally said that the shrinkage ratio error is ± 0.5%. This is a problem common to those involving the sintering of multilayer ceramic substrates.

Therefore, conventionally, in the production of a ceramic substrate, a substrate-constituting sheet is produced, an electrode pattern is formed with a conductor paste, and a desired number of electrode-pattern-formed sheets other than the substrate-constituting sheet are laminated. After that, a shrinkage suppression sheet that does not sinter at the firing temperature of the substrate constituting sheet is sandwiched on both sides or one side of the substrate constituting sheet laminated body, and the laminated body is fired. After that, a method of producing a multilayer ceramic substrate which does not cause shrinkage during firing by removing the non-sintering shrinkage suppression sheet, and printing and firing the surface layer surface is used.

An example of the conventional method for manufacturing the above-mentioned multilayer ceramic substrate will be described below with reference to the drawings. 3A to 3F show a manufacturing process of a conventional multilayer ceramic substrate. As shown in FIGS. 3A and 3B, the substrate constituting sheet 11 and the shrinkage suppressing sheet 12 are formed on the film 13 by a sheet forming process. As the material of the shrinkage suppression sheet 12, a material having a higher sintering temperature than the substrate constituent sheet 11 is used. The substrate-constituting sheet thus formed is perforated as shown in FIG.
The hole is filled with the conductor paste 14. Next, Fig. 3
As shown in (d), the shrinkage suppression sheet 12 is the uppermost layer / lowermost layer, and a plurality of substrate constituting sheets 11 are sequentially laminated.
At this time, the inner layer conductor pattern 15 is provided between the substrate sheets 11.
Is formed. This laminated sheet is fired at a temperature at which only the substrate-constituting sheet 11 is sintered. Then, as shown in FIG. 3E, the shrinkage suppression sheet 1 that could not be sintered at the above temperature.
The uppermost layer and the lowermost layer consisting of 2 are removed, and the conductor pattern 16 is formed on the surface layer surface as shown in FIG. As a result, a multilayer ceramic substrate is manufactured.

[0007]

However, in the above-mentioned structure, since the shrinkage does not occur, the surface wiring can be performed at the same time as the inner layer firing. However, in the conventional wiring pattern printing method, the structure of the substrate with the film is used. In order to fix the substrate-constituting sheet with a sheet or a frame, it was most efficient to print on the surface opposite to the film surface and sequentially stack. However, in this case, a wiring pattern must be formed on both surfaces (inner layer portion and surface layer portion) of the lowermost substrate constituting sheet, and for example, in a substrate constituting sheet with a film, the film must be peeled off and printed. However, there is a problem with the position accuracy. Further, in the case of fixing the substrate component sheet by a frame or the like, printing is performed on both sides of the substrate component, which causes a problem in printing accuracy, and this method is not suitable for continuous production.

In view of the above problems, it is an object of the present invention to provide a multilayer ceramic substrate and a method for manufacturing the same which facilitates the surface wiring to be performed simultaneously with the inner layer firing.

[0009]

In order to achieve the above-mentioned object, the present invention comprises the steps of forming a substrate-constituting sheet in a film on a roll, making holes in the substrate-constituting sheet, and filling the holes with a conductor paste. After forming the steps and the electrode pattern, the substrate constituting sheet is peeled off and cut from the roll, the substrate constituting sheet which is the lowermost layer is inverted so that the electrode surface side is the surface, and the substrate constituting sheet is placed thereon. A method for manufacturing a multilayer ceramic substrate includes a step of laminating without inverting and a step of laminating a plurality of substrate constituent sheets in sequence without inverting, and a step of firing the laminated multilayer sheets.

[0010]

According to the present invention, it is possible to easily realize the surface wiring at the same time as the inner layer firing by the above method.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1A and 1B, the substrate-constituting sheet 1 and the shrinkage suppression sheet 2 are formed on the film 3 on the roll by a sheet forming process. The substrate-constituting sheet 1 is a low temperature sintering material in which glass is contained in alumina. As the material of the shrinkage suppression sheet 2, a material having a sintering temperature higher than that of the substrate constituent sheet 1 is used. The board-constituting sheet 1 thus formed is perforated as shown in FIG. 1C, and the holes are filled with the conductor paste 4.
Copper oxide is generally used as a main material of the conductor paste 4, but other materials such as silver, silver-palladium, silver-platinum, and copper may be used. Next, as shown in FIG. 1D, an inner layer conductor pattern 5 is formed on the surface of the constituent substrate 1, peeled from the film 3 on the roll, and cut into a specified size. The shrinkage suppression sheet 2 is the uppermost layer / lowermost layer, and a plurality of substrate constituting sheets 1 are sequentially laminated as shown in FIG. At this time, the substrate sheet 1, which is the lowermost layer, is inverted so as to have a surface layer pattern, and the next substrate constituent sheets are laminated without being inverted. The laminated sheet is fired at a temperature at which only the substrate-constituting sheet 1 is sintered. And Figure 1
As shown in (f), the uppermost layer and the lowermost layer made of the shrinkage suppression sheet 2 that could not be sintered at the above temperature are removed.

As described above, according to this embodiment, the substrate-constituting sheet 1 is formed on the roll and the upper film 3, the substrate-constituting sheet is perforated, the conductor paste 4 is filled, and the conductor pattern 5 is formed. The substrate constituting sheet, which is the lowermost layer, is inverted so that the conductor pattern 5 side is the front side, and the substrate constituting sheet is laminated thereon without being inverted, and further, a plurality of substrate constituting sheets are sequentially laminated and laminated. By sintering the multilayer sheet, it is possible to easily realize that the surface wiring is performed simultaneously with the inner layer firing.

A second embodiment of the present invention will be described below with reference to the drawings. 2 (a) to 2 (i) show manufacturing steps of the multilayer ceramic substrate in the embodiment of the present invention. As shown in FIGS. 2A, 2B, and 2C, the substrate-constituting sheet 1a, the shrinkage suppression sheet 2, and the second substrate-constituting sheet 1b having a thickness half that of the substrate-constituting sheet 1 are formed by the sheet forming process. It is formed on the film 3. The material of the substrate-constituting sheet 1a and the second substrate-constituting sheet 1b is a low temperature sintering material in which glass is contained in alumina. The two substrate constituent sheets 1a and 1b thus formed are shown in FIG.
Holes are drilled as shown in (d) and (e), and the holes are filled with the conductor paste 4. Copper oxide is generally used as a main material of the conductor paste 4, but other materials such as silver, silver-palladium, silver-platinum, and copper may be used. Next, as shown in FIGS. 2F and 2G, a conductor pattern 5 is formed and peeled from the film 3 on the roll,
Cut to the specified dimensions. The shrinkage suppression sheet 2 is the uppermost layer / lowermost layer, and a plurality of substrate constituting sheets 1 are sequentially laminated as shown in FIG. At this time, the second substrate-constituting sheet 1b is inverted to form the lowermost layer, the second substrate-constituting sheet 1b is then laminated without inversion, and further a plurality of substrate-constituting sheets 1a are sequentially laminated. Bake the sheet. Then, as shown in FIG. 2 (i), the uppermost layer and the lowermost layer made of the shrinkage suppression sheet 2 that could not be sintered at the temperature are removed.

As described above, according to this embodiment, the two types of substrate constituting sheets 1a and 1b, that is, the substrate constituting sheet 1a and the second substrate constituting sheet 1b having a thickness half that of the substrate constituting sheet 1a are provided. In preparation, holes are punched in both the substrate constituting sheets 1a and 1b, the conductor paste 4 is filled in, the conductor pattern 5 is formed, and the second substrate constituting sheet 1b is inverted so that the electrode surface side is the surface to form the lowermost layer, The second board-constituting sheet 1b is laminated thereon without being inverted, a plurality of the first board-constituting sheets 1a are further laminated in sequence, and the laminated multi-layer sheet is baked, whereby the surface layer wiring is baked as an inner layer. At the same time, it can be easily realized.

[0015]

As is apparent from the above description of the embodiments, the present invention forms a green sheet on a film on a roll, punches holes in the green sheet, fills with a conductive paste, forms an electrode pattern, and forms a bottom layer. By inverting the green sheet to be the electrode side, the green sheets are laminated on the green sheet without inverting, a plurality of green sheets are sequentially laminated, and the laminated multilayer sheet is fired. The surface wiring can be easily baked simultaneously with the inner layer pattern.

[Brief description of drawings]

FIG. 1 is a sectional view showing a manufacturing process of a multilayer ceramic substrate according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a manufacturing process of a multilayer ceramic substrate according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a manufacturing process of a conventional multilayer ceramic substrate.

[Explanation of symbols]

 1 Substrate constituent sheet 2 Shrinkage suppression sheet 3 Film 4 Conductor paste 5 Conductor pattern

Claims (6)

[Claims] 1. A plurality of ceramic substrates are laminated, and inner layer conductor patterns formed on respective surfaces of the ceramic substrates are connected by electrodes penetrating the ceramic substrates, and the innermost layer is a lowermost layer or an uppermost layer. A multilayer ceramic substrate in which the ceramic substrate on which the conductor pattern is formed is inverted to form an electrode pattern on the surface layer so that the inner layer and the surface layer can be simultaneously fired. 2. A film on a roll, a step of forming a green sheet, a step of forming a hole in the green sheet and filling a conductive paste in the hole, and after forming an electrode pattern, the green sheet is peeled from the roll.・ Cut and invert the green sheet that is the bottom layer so that the electrode surface side is the surface, and stack the green sheets on it without inverting them, and further stack multiple green sheets without inverting them. A method of manufacturing a multi-layer ceramic substrate comprising the steps of: firing a laminated multilayer sheet. 3. A film on a roll, wherein a step of forming a first green sheet and a green sheet having a thickness half that of the first green sheet, and the first and second green sheets are formed. A step of forming a hole and filling a conductive paste in the hole; a step of peeling and cutting each green sheet from a roll after forming an electrode pattern; and a step of reversing the second green sheet to form a lowermost layer, and a second green sheet A method for manufacturing a multilayer ceramic substrate, which comprises the steps of stacking without inverting and further stacking a plurality of first green sheets in sequence, and the step of firing the stacked multilayer sheets. 4. The green sheet comprises a substrate constituent sheet and a shrinkage suppression sheet.
A method for manufacturing the multilayer ceramic substrate as described above. 5. The shrinkage suppression sheet has a higher sintering temperature than the substrate constituent sheet, and is sintered at a temperature within the range of the sintering temperature of the shrinkage suppression sheet and the sintering temperature of the substrate constituent sheet, and shrinks after sintering. The method for manufacturing a multilayer ceramic substrate according to claim 4, wherein the suppressing sheet is removed. 6. The conductive paste is Ag, Ag / Pd, A
4. The method for manufacturing a multilayer ceramic substrate according to claim 2, wherein one of g / Pt and Cu is a main component.