JP3995294B2 - Manufacturing method of ceramic laminated substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a ceramic laminated substrate by laminating a plurality of green sheets in a state where conductors are formed so that the respective layers are electrically connected, pressurizing, and firing.
[0002]
[Prior art]
A conventional method for manufacturing a ceramic laminated substrate is shown in FIG. First, a plurality of ceramic green sheets 1 are prepared (see FIG. 5A), then through holes are formed in each green sheet, and conductors 2 are filled in the through holes (see FIG. 5B). A conductor 3 (including the conductor 3a of the conductor land portion) is printed and formed on each green sheet for wiring formation (see FIG. 5C). And all the green sheets are laminated | stacked and it pressurizes with a press (refer FIG.5 (d)). Thereafter, firing is performed to obtain a ceramic laminated substrate.
[0003]
The surface of the conductor 3a formed on the outermost conductor land portion is subjected to metal plating on the ceramic multilayer substrate manufactured in this way to form a conductor land, and then a solder paste is screened on the conductor land. Print. Thereafter, the solder bumps formed on the electrode terminals of the flip chip IC are aligned on the conductor land on which the solder paste is printed, and reflow is performed to solder-connect the flip chip IC onto the ceramic multilayer substrate.
[0004]
[Problems to be solved by the invention]
In the manufacture of the ceramic laminated substrate described above, the conductor 3 (3a) formed on the outermost layer is embedded in the green sheet by the pressure applied after the lamination. For this reason, the height of the conductor 3 (3a) from the substrate surface after firing becomes low, for example, about 10 μm.
[0005]
Therefore, when the flip chip IC is solder-connected using the conductor 3a formed on the conductor land portion, the gap between the flip chip IC and the ceramic laminated substrate is narrowed. In this case, if a large flip chip IC is used and the pitch between the electrode terminals is narrow, thermal stress is applied to each of the flip chip IC and the ceramic laminated substrate due to the difference in thermal expansion coefficient, and the flip chip IC electrodes There arises a problem that the bonding strength of the solder joint between the terminal and the conductor land is lowered.
[0006]
To reduce the bonding strength, it is conceivable to inject and fill a reinforcing resin into the gap between the flip chip IC and the ceramic laminated substrate. However, as described above, the gap is narrowed. Therefore, resin injection is difficult. Further, in a ceramic laminated substrate, warping may occur due to firing shrinkage in a region where a flip chip IC is mounted, and at this time, it becomes more difficult to inject a resin.
[0007]
In order to increase the conductor 3a of the conductor land, a method of increasing the thickness of the conductor at the time of printing or increasing the thickness of the conductor by performing printing a plurality of times can be considered. Since it is embedded in the sheet, it is difficult to expect the effect. Further, it is conceivable to increase the thickness of the metal plating formed on the conductor 3a in the conductor land portion, but in this case, a cost problem arises.
[0008]
The present invention has been made in view of the above problems, and an object of the present invention is to enable a conductor in a conductor land portion to be formed high even after firing.
[0009]
[Means for Solving the Problems]
The present invention pays attention to the fact that the conductor in the conductor land portion does not become high in the pressurization after the lamination, and achieves the above object by performing the conductor printing of the conductor land portion after the lamination press. Specifically, in the invention described in claim 1, a plurality of green sheets (1) are laminated in a state in which conductors (2, 3) are formed so that the respective layers are electrically connected, and the outermost layer conductor is formed. After pressurizing a plurality of green sheets in a state where the conductor (3a) is printed on the land portion , the conductor ( 3b ) is printed again on the conductor of the conductor land portion , and then no pressure is applied. It is characterized by firing.
[0010]
Therefore, since the conductor printing of the conductor land portion is performed after the lamination press, the conductor of the conductor land portion from the substrate surface can be increased after firing. In this case, if the conductor of the conductor land portion is formed by the conductor (3a) formed before the lamination and pressurization and the conductor (3b) formed after the pressurization as in the invention described in claim 1 , In addition, the conductor of the conductor land portion can be increased.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
First, in each embodiment described below, the first embodiment corresponds to the embodiment of the invention described in the claims, and the second and third embodiments are reference examples.
(First Embodiment) FIG. 1 shows a method for manufacturing a ceramic laminated substrate according to an embodiment of the present invention. First, a plurality of ceramic green sheets 1 containing alumina as a main component are prepared (see FIG. 1A). Next, through holes are formed in each green sheet by a method such as punching using a die. Is filled with a conductor 2 whose main material is molybdenum (see FIG. 1B). Then, on each green sheet, a conductor 3 made of tungsten as a main material is printed and formed for wiring formation (see FIG. 1C). At this time, the conductor 3a on the outermost conductor land is also printed. And all the green sheets are laminated | stacked and it pressurizes with a press (refer FIG.1 (d)). Thereafter, the conductor 3b is printed again on the conductor 3a of the conductor land portion (see FIG. 1 (e)), and firing is performed in a reducing atmosphere at a temperature of about 1600 ° C. without applying pressure by a press. To obtain a ceramic laminated substrate.
[0012]
According to such a manufacturing method, after laminating and pressing the green sheets, the conductor 3b is printed and formed on the conductor land portion. After that, firing is performed without applying pressure. It can be increased after firing.
Thereafter, metal plating is applied to the surface of the conductor 3b of the conductor land portion on the outermost layer to ensure solder wettability. The plating material is preferably a metal with good solder wettability such as Cu, Ni, Au. The plating method may be any of electroless plating and electrolytic plating.
[0013]
The configuration of the conductor land thus configured is shown in FIG. The first conductor 3a printed and formed before the green sheet is laminated and pressed has a height lower than 10 μm from the surface after firing, but the second conductor 3b printed and formed after the lamination and press is When the height is 15 μm after firing and the thickness of the metal plating 4 is 10 μm, the total height of the conductor lands is about 35 μm, so that a sufficient height can be obtained.
[0014]
After forming the conductor lands in this way, a solder paste is screen-printed on the conductor lands. Then, the solder bump formed on the electrode terminal of the flip chip IC is positioned on the conductor land on which the solder paste is printed, and reflow is performed to solder-connect the flip chip IC onto the ceramic multilayer substrate.
(Second Embodiment)
FIG. 3 shows a method for manufacturing a ceramic laminated substrate according to the second embodiment of the present invention.
[0015]
In this embodiment, the conductor 2 is filled in the through hole of each green sheet 1, and the conductor 3 is printed and formed on each green sheet for wiring formation (see FIG. 3A). However, the conductor on the outermost conductor land is not printed. And all the green sheets are laminated | stacked and it pressurizes with a press (refer FIG.3 (b)). Thereafter, the conductor 3c of the outermost conductor land portion is printed and formed (see FIG. 3C), and thereafter, as in the first embodiment, firing is performed without pressing.
[0016]
Therefore, according to this embodiment, the height of the conductor land is reduced by the absence of the first-layer conductor 3a compared to the first embodiment, but the conductor printing of the conductor land portion is performed after the lamination press. The conductor land can be made higher than the conventional one.
(Third embodiment)
FIG. 4 shows a method for manufacturing a ceramic laminated substrate according to the third embodiment of the present invention.
[0017]
In this embodiment, the conductor 2 is filled in the through hole of each green sheet 1, and the conductor 3 is printed and formed on each green sheet for wiring formation (see FIG. 4A). However, the outermost layer conductor is not formed by printing. And all the green sheets are laminated | stacked and it pressurizes with a press (refer FIG.4 (b)). Thereafter, the outermost conductors 3d and 3c are formed by printing (see FIG. 4C), and thereafter, as in the first embodiment, firing is performed without pressing.
[0018]
Therefore, in this embodiment, similarly to the second embodiment, the conductor land can be made higher than the conventional one. Note that the conductor 3d of the other conductor portion becomes higher in the same manner as the conductor 3c of the conductor land portion, but there is no problem if it is used as a normal wiring and land.
In the first to third embodiments described above, the green sheets are stacked and pressed all at the same time. However, the conductor printing and the stacking and pressing may be alternately performed layer by layer. .
[0019]
Further, the green sheet is not limited to the one having alumina as a main component, and may be one having glass as a main component.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a method for producing a ceramic laminated substrate according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a configuration of conductor lands in a ceramic laminated substrate manufactured by the method shown in FIG.
FIG. 3 is a process diagram showing a method for manufacturing a ceramic laminated substrate according to a second embodiment of the present invention.
FIG. 4 is a process diagram showing a method for manufacturing a ceramic laminated substrate according to a third embodiment of the present invention.
FIG. 5 is a process diagram showing a conventional method for manufacturing a ceramic laminated substrate.
[Explanation of symbols]
1 ... green sheet, 2, 3 ... conductor, 4 ... metal plating.

Claims (1)

A plurality of green sheets (1) are laminated in a state in which conductors (2, 3) are formed so that the respective layers are electrically connected. After pressing the plurality of green sheets, firing is performed to form a ceramic laminate. In a method of manufacturing a substrate,
Wherein after pressurization was carried out in a stacked and conditions the conductor lands of the outermost layer formed by printing a conductor (3a), said conductor land portions again conductor (3b) formed by printing on the conductor, after which the pressure A method for producing a ceramic laminated substrate, wherein the firing is performed without applying pressure.

Images