JPH07105597B2 - Method for manufacturing multilayer ceramic substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a method for manufacturing a multilayer ceramic substrate, which is capable of highly accurately adjusting flatness of both front and back surfaces of a ceramic substrate, parallelism of both front and back surfaces and plate thickness dimension by minimum necessary polishing. In addition, for the purpose of surely preventing the damage of the pattern layer due to polishing, different patterns are formed on the front surface side and the back surface side of the pattern layer formed of a group of green sheets on which the required conductor patterns are formed.
In the method for manufacturing a multilayer ceramic substrate in which a polishing layer composed of a group of green sheets is laminated, a green sheet serving as a thickness adjusting margin is laminated on one of the front and back polishing layers, and a parallelism adjusting margin is formed on each of the front and back polishing layers. After laminating a green sheet that becomes a flatness adjusting margin and a green sheet that becomes a flatness adjusting margin in order, and providing a display means for displaying the stacking order on each green sheet laminated on each front and back polishing layer, each polishing layer The green sheets of No. 2 were laminated in order according to the stacking order.

[Industrial application field]

The present invention relates to a method for manufacturing a multilayer ceramic substrate used in, for example, a large-scale electronic computer, and in particular, it is precise in adjusting the flatness of both front and back surfaces, parallelism adjustment, and plate thickness dimension to the extent that it can support cooling systems such as forced water cooling. The present invention relates to a method for manufacturing a multilayer ceramic substrate, which can be adjusted by polishing to a minimum necessary amount, and a method for manufacturing a multilayer ceramic substrate, which allows the position of a polished polishing layer to be easily determined.

[Conventional technology]

2. Description of the Related Art In recent years, as a large amount of information is exchanged and processed in every scene of human society, the processing speed of electronic computers used for processing various information has become faster and the processing functions have become more diverse. It is being promoted extremely rapidly.

For this reason, a multi-layer ceramic substrate that can make the circuit density extremely high is adopted. Furthermore, in order to increase the processing speed, mainly, a multi-layer ceramic substrate is formed on the surface of the multi-layer ceramic substrate.
A technique has been developed in which a layer or a plurality of layers of conductor pattern layers and insulating layers are formed, and surface-mounted components are mounted on the surface conductor pattern layers.

At this stage, one or more conductor pattern layers and insulating layers (hereinafter, these layers formed on the surface of the multilayer ceramic substrate are formed on the surface of the multilayer ceramic substrate by a thin film forming method such as sputtering or vacuum deposition. Is collectively referred to as a surface thin film layer), the flatness and smoothness of the surface of the multilayer ceramic substrate have been problems.

That is, in a ceramic substrate, warpage or undulation occurs in the firing process and the surface thereof is relatively rough, which may be an obstacle to forming the surface thin film layer uniformly over the entire surface of the ceramic substrate. Was experienced.

This problem is caused on the front surface side and the back surface side of the pattern layer formed of a group of green sheets on which a required conductor pattern is formed,
A polishing layer made of a group of different green sheets in which via conductors for connecting the conductor pattern on the front surface or the back surface of the pattern layer to the conductor pattern of the surface thin film layer are embedded is laminated, and after firing, each polishing layer is lapped, for example. It is solved by the method of polishing using.

The thickness of the polishing layer to be laminated is empirically determined, and therefore the number of layers of the green sheet to be laminated as the polishing layer is also empirically determined. For example, in the case of manufacturing a multilayer ceramic substrate having a length of about 360 mm and a finished thickness of about 14 mm, 19 layers of green sheets are laminated on the front side of the pattern layer and 17 layers of green sheets are laminated on the back side. .

By the way, in order to further increase the processing speed and multifunction of the electronic computer, a measure for increasing the substrate density is adopted. A particularly problematic issue in increasing the substrate density is how to efficiently cool the substrates assembled in high density. As a method of cooling the substrate, a coolant cooling method that uses water, a volatile liquid, or the like as a coolant has recently come into the limelight.

A water-cooling method, which is typical among the refrigerant cooling methods, stores a multilayer ceramic substrate 101 in a package 102, for example, as shown in FIG. 3, and installs a cooling transmission piston 103 from one side of the package 102 to the multilayer ceramic substrate. The water (refrigerant) circulated in the piston 103 is brought into contact with the surface mount component 104, and the heat generated by the surface mount component 104 is absorbed to be carried out of the package 102.

[Problems to be Solved by the Invention]

By the way, in the conventional method for manufacturing a multilayer ceramic substrate, both front and back surfaces can be formed flat and smooth by polishing the front and back surfaces of the ceramic substrate. Was not considered at all.

Therefore, when the conventional multilayer ceramic substrate is enclosed in the package 102 as shown in FIG. 3, the piston 103 cannot contact the surface mount component 104, the surface mount component 104 cannot be cooled, or the piston 103 is surface mount. There was a case where the surface mount component 104 was damaged by being strongly pressed against the component 104.

Therefore, it was attempted not only to increase the flatness and smoothness of the front and back surfaces at the time of polishing the ceramic substrate by increasing the thickness of the polishing layer, but also to improve the parallelism and the plate thickness dimensional accuracy. Even if the layer was made quite thick, it was not uncommon for the patterned layer to be damaged by polishing.

That is, in order to prevent the pattern layer from being polished,
It is necessary to confirm at which position on the ceramic substrate 101 the pattern layer is located.For this purpose, conventionally, there is only a method of cutting the ceramic substrate 101 and examining its cross section, which is to be used later. It is not possible to confirm at which position of the ceramic substrate 101 being polished the pattern layer is located. As a result, the amount of wear was excessive on one side, and the inner layer conductor pattern of the pattern layer was frequently polished and destroyed, resulting in frequent failures.

In the conventional method for manufacturing a multilayer ceramic substrate in which the thickness of the polishing layer is empirically determined, in order to prevent such a failure, the number of green sheets of the polishing layer to be laminated on the front and back surfaces is ultimately determined. Inevitably, the amount of polishing as a whole increases and the polishing time becomes extremely long. Moreover,
Even if the polishing layer is thickened, it cannot be guaranteed that the pattern layer can be reliably prevented from being damaged during polishing.

The present invention has been made in view of the above circumstances, and has a large plate thickness dimension, and even in a multilayer ceramic substrate having a large area, precise flatness adjustment over the entire surface,
It is an object of the present invention to provide a method for manufacturing a multilayer ceramic substrate, in which the parallelism adjustment and the plate thickness adjustment can be performed by the minimum necessary polishing, and further, the damage of the pattern layer due to the polishing can be surely prevented.

[Means for Solving the Problems]

For example, as shown in FIG. 1, the present invention provides a multilayer ceramic substrate in which a group of polishing layers 3a and 3b are laminated on the front surface side and the back surface side of a group of pattern layers 2 on which a required conductor pattern is formed. In the manufacturing method, the following measures are taken to achieve the above object.

That is, one of the front and back polishing layers 3a and 3b has a thickness adjustment allowance.
Along with 32 layers, the parallelism adjustment allowances 33a and 33b and the flatness adjustment allowances 34a and 34b are laminated on each of the front and back polishing layers 3a and 3b, and the green sheet GS that constitutes each polishing layer 3a and 3b is formed. After providing the display means m for displaying the stacking order, each polishing layer 3a
・ Measures are taken to sequentially stack the 3b green sheets GS according to their stacking order.

[Action]

The laminated pattern layer 2 and both polishing layers 3a and 3b are heated and pressed to be pressure-bonded to each other, and then fired to form the ceramic substrate 1. The fired ceramic substrate 1 is adhered to a pallet made of, for example, glass and polished from the surface side. Then, when all of the flatness adjustment allowance 34a on the front surface side has been polished, the front surface side polishing is temporarily terminated. Whether or not all the flatness adjustment allowances 34a on the front surface side have been polished is easily determined by looking at the display means m of the green sheet GS on the polished surface or the green sheet GS below it. By this polishing, the surface of the ceramic substrate 1 is polished into a flat surface having a predetermined flatness and smoothness.

After that, the ceramic substrate 1 is peeled off from the pallet, inverted and adhered again, and then the flatness adjustment allowance 34b and the parallelism adjustment allowance 33b on the back side are similarly polished. In this case, by looking at the display means m of the green sheet GS on the polishing surface or the green sheet GS below it, when the polishing has a thickness adjustment allowance on the pattern layer 2 or the back side, a thickness adjustment allowance 32 And the parallelism adjustment allowance 33b has been reached, it is judged whether polishing has reached the pattern layer 2 or the thickness adjustment allowance.
Immediately before reaching 32, polishing is completed. As a result, the back surface of the ceramic substrate 1 is finished into a flat surface having a predetermined flatness and smoothness, and the parallelism of the back surface with respect to the front surface is reliably increased to a predetermined reference value or higher. Further, by stopping the polishing immediately before reaching the pattern layer 2 or the thickness adjustment allowance 32, it is possible to prevent the polishing from proceeding to the pattern layer 2 or the thickness adjustment allowance 32 on the back surface side.

Further after this, the ceramic substrate 1 is peeled off from the pallet,
After re-inverting and adhering again, start polishing the surface side,
The surface side parallelism adjustment allowance 33a is polished. In this polishing as well, the polishing reaches the boundary between the pattern layer 2 or the thickness adjustment margin 32 and the parallelism adjustment margin 33a by looking at the display means m of the green sheet GS on the polishing surface or the green sheet GS below it. It is determined whether or not the polishing is performed, and the polishing is finished immediately before the polishing reaches the pattern layer 2 or the thickness adjustment allowance 32. As a result, both the front and back surfaces of the ceramic substrate 1 are finished to have a predetermined flatness and smoothness, respectively, and the parallelism of the front and back surfaces is ensured to be equal to or higher than a predetermined accuracy, and polishing is performed on the front surface side. It is prevented that the pattern layer 2 or the thickness adjustment allowance 32 is reached.

Finally, the surface on which the thickness adjustment margin 32 is laminated is polished within a range until just before the pattern layer 2 appears on the polished surface, and the plate thickness is adjusted to a predetermined value.

Thus, the front and back surfaces are flat and smooth without polishing the pattern layer 2 and finished parallel to each other.
It is possible to obtain a ceramic substrate having a predetermined plate thickness over the entire surface.

After finishing the polishing, by looking at the display means m of the green sheet GS on the polishing surface or the green sheet GS below it, it is determined whether the polishing exceeds the boundary between the pattern layer 2 and the thickness adjustment allowance 32. Can be determined.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, in the method for manufacturing a multilayer ceramic substrate according to one embodiment of the present invention, a pattern in which a large number (for example, about 70 sheets) of green sheets GS on which required conductor patterns are formed are laminated in a predetermined order. Layer 2 is laminated in a sandwich form between two groups of polishing layers 3a, 3b, each group being a separate group. Then, after firing this laminated body, it is cut at a predetermined position to form a plate shape having a side of about 360 mm, and polished to be adjusted to a predetermined plate thickness, for example, 14 mm.

In the laminating step, first, the green sheets GS forming the re-polishing margins 31a and 31b are laminated on both front and back surfaces of the pattern layer 2.

The re-polishing allowances 31a and 31b are used for the surface conductor formed on the surface of the ceramic substrate 1 in the subsequent thin film forming step or in the formation of a conductive pattern on the surface of the ceramic substrate 1 or in the steps after the thin film forming step. When the pattern is damaged, the front surface or the back surface of the ceramic substrate 1 is re-polished to an extremely thin thickness of, for example, about 0.1 mm together with the defective surface thin film layer to remove the ceramic substrate 1 and the undamaged surface thin film layer. It is provided so that it can be reused. Each repolishing fee 31
The thickness of a and 31b is limited within the range of the plate thickness error that is finally allowed (for example, ± 0.5 mm). Each repolishing fee 31a
・ The number of layers of green sheet GS that composes 31b is 3 regrinding allowances.
The rate at which the green sheet GS shrinks in the thickness direction when firing the thickness of 1a and 31b, that is, the firing shrinkage rate (here, about 3 /
It is obtained by dividing by 2) and further dividing by the thickness of one layer of green sheet GS. For example, the thickness of each re-polishing margin 31a and 31b is 0.
When the thickness of the green sheet GS is 5 mm and the thickness of the green sheet GS is about 0.3 mm, the number of layers is 2.5 (two layers in the figure).

Here, the number of layers of the green sheet GS does not have to be an integer, and the green sheet to be laminated later as the thickness adjustment allowance 32, the parallelism adjustment allowances 33a and 33b or the flatness adjustment allowances 34a and 34b.
The total number of layers with GS should be an integer.

The thickness of the pattern layer 2 is the green sheet GS to be laminated.
Is determined by the thickness and the number of layers, for example, the thickness is about 0.3 mm
If 70 layers of the green sheets GS are laminated, the thickness of the pattern layer 1 becomes about 21 mm. In the case of this pattern layer 1, it has been experienced that the thickness thereof shrinks to about 14 mm after firing. However, the shrinkage amount of the pattern layer 1 during firing depends on the area, film thickness, plane shape of the formed conductor pattern,
It is known that, depending on the distribution state, etc., in reality, there is a dimensional error of approximately ± 1 mm with respect to the finished plate thickness of 14 mm after firing.

Therefore, in order to adjust this dimensional error, the thickness adjustment
The green sheets GS forming 32 are laminated with the re-polishing margin 31a.

The thickness of the thickness adjustment allowance 32 may be obtained by dividing the above firing dimensional error by the firing shrinkage ratio, and the number of layers of the green sheet GS constituting the thickness adjustment allowance 32 is further calculated as the thickness of the green sheet GS. Divide by.

In this embodiment, since the thickness of the green sheet GS is 0.3 mm, the number of layers of the green sheet GS forming the thickness adjustment allowance 32 is five.

Further, when the laminate of the pattern layer 1, the repolishing margins 31a and 31b on both sides and the thickness adjusting margin 32 is fired, both sides form a pair of front and back flat surfaces having required flatness and smoothness. In order to adjust the parallelism between the front and back surfaces, the green sheets GS forming the parallelism adjustment margins 33a and 33b are laminated on the front and back surfaces.

In this case, it has been empirically confirmed that an error of ± 1 mm occurs, so the thickness of the parallelism adjustment margins 33a and 33b is determined so that an error of ± 0.5 mm can be eliminated on one side. . That is, the thickness of the parallelism adjustment margins 33a and 33b on one side is 0.5 mm.
Is divided by the firing shrinkage to be 0.75 mm, and the number of layers of the green sheet GS is 2.5 (three in the figure).

Furthermore, in addition to these parallelism adjustment allowances 33a and 33b, in order to eliminate deformation such as warpage and undulation of each surface, flatness adjustment allowance 34a
-The green sheets GS that compose 34b are stacked.

The thickness of each flatness adjustment allowance 34a / 34b can be obtained by dividing the maximum value of the warpage or waviness of each surface generated during firing by the firing shrinkage rate. Ceramic substrate 1 of the same kind as this embodiment
Since it has been confirmed that a maximum of ± 3 mm of warpage or undulation with respect to the reference plane occurs, the thickness of each flatness adjustment allowance 34a ・ 34b is 4.5 mm, and each flatness adjustment allowance 34a ・ 34a ・
The number of layers of the green sheet GS constituting 34b is 15 layers.

After all, in this embodiment, 25 layers of green sheets GS are laminated on the upper side of the pattern layer 2 and 20 layers of green sheets GS are laminated on the lower side thereof.

Then, as shown in FIG. 2, each green sheet GS has a predetermined area outside the pattern formation area of the pattern layer 2 (may be within this area) before the next green sheet GS is laminated. A number m indicating the stacking order of the green sheet and GS is attached to a portion corresponding to the portion, that is, a corner portion of each green sheet GS.

The method of forming the number m is not particularly limited, and a method such as printing, punching, or embossing is used. Here, in order to avoid an increase in the number of steps and to reduce the cost, for example, by printing the metal paste on one end of the via hole of each green sheet GS at the same time as printing the metal paste, the number m Are formed.

Instead of the number m, plot marks, bar code marks, etc. may be provided on the green sheet GS.

In this method for manufacturing a multilayer ceramic substrate, the green sheets GS are laminated on both sides of the pattern layer 2 as the polishing layers 3a and 3b in the minimum necessary thickness in this manner. Then, in the laminated body thus manufactured, the green sheets GS of the pattern layer 2 and the polishing layers 3a and 3b laminated on both sides of the pattern layer 2 are heated and pressed to be pressure-bonded to each other and fired to form the ceramic substrate 1. To form,
It is brought into a polishing process to form thin film conductor pattern layers on both front and back surfaces.

In the polishing step, first, for example, the flatness adjustment allowance 34a of the polishing layer 3a on the front surface side is polished.

At any point during this polishing, by looking at the number m of the green sheet GS (or the number m of the green sheet GS below it) on the polished surface of the ceramic substrate 1, the green being polished at that time can be seen. It is possible to easily determine whether or not the sheet GS is also the flatness adjustment allowance 34a. Then, at the end of or before or after the polishing of the green sheet GS of the last layer of the flatness adjustment allowance 34a, the polishing layer 3a
The polishing of is once stopped.

After that, the ceramic substrate 1 is turned over and the polishing layer on the other side is reversed.
The flatness adjustment allowance 34b of 3b is polished. In addition, subsequently to this, the polishing surface of the polishing layer 3b is the polishing layer 3a which is first polished.
The thickness of the parallelism adjusting margin 33b is polished so as to be parallel to the polishing surface of. It is judged from the number m on the green sheet GS which layer the parallelism adjustment allowance 33b has been polished, and the re-polishing allowance 31
Immediately before b appears on the polished surface, polishing of the back surface side is stopped and the ceramic substrate 1 is re-inverted. Then, one surface (upper surface) of the parallelism adjustment allowance 33a and the thickness adjustment allowance 32 on the one surface side is parallel to the opposite surface (lower surface), and the plate thickness of the ceramic substrate 1 has a predetermined finish dimension. Polish until the maximum value is reached.

In this way, the dimensional error of the plate thickness of the ceramic substrate 1, the flatness of each surface, and the parallelism of both surfaces can be adjusted within ± the expansion and contraction width of the water-cooling piston 103 without wastefully polishing the polishing layers 3a and 3b. It was possible to make it much smaller than about 0.5 mm and below ± 0.2 mm.

In short, according to this method for manufacturing a multilayer ceramic substrate, both front and back surfaces are finished flat, smooth, and parallel to each other, and the plate thickness is adjusted with high accuracy. As a result, refrigerant cooling package 1012 such as water cooling
Surface mount component 104 mounted on the surface when assembled into
The cooling piston 103 can be contacted with an appropriate contact pressure for reliable cooling, and insufficient cooling or damage to the surface-mounted component 104 can be prevented.

Moreover, since the thickness of the polishing layers 3a and 3b is determined to be the minimum necessary, the polishing time can be shortened to the minimum necessary.

The green sheet GS becomes thicker in the central portion due to the pressure applied during lamination, and the green sheet GS closer to the pattern layer 2 than the peripheral portion is polished in the central portion of the ceramic substrate 1. However, in this case, as shown in FIG. 2, the boundary line B1 between the green sheet GS exposed on the central side and the green sheet GS exposed on the outside thereof is
Since the adhesion state of the abrasive changes at B2 and the boundary lines B1 and B2 look concentric like tree rings, these boundary lines B1 and B2
It is possible to easily determine the stacking order of the green sheet GS closest to the pattern layer 2 that is exposed from the number of the green sheets and the number m attached to the green sheet GS. Therefore, by stopping the polishing before the pattern layer 2 is polished, it is possible to surely prevent excessive polishing of only one surface of the ceramic substrate 1, and it is possible to surely prevent generation of defective products due to destruction of the conductor pattern of the pattern layer 2. can do.

Further, according to this method for manufacturing a multilayer ceramic substrate, since the re-polishing layers 31a and 31b are laminated, the thin film conductor pattern layer formed later on the surface of the ceramic substrate 1 is defective when it is formed or damaged. Re-polishing layer 31 with the surface thin film layer of
By polishing a / 31b, the ceramic substrate 1 and a good surface thin film can be saved from disposal. In addition,
Also in the case of re-polishing, it is possible to judge whether the re-polishing can be done or the scrap should be discarded by looking at the number m provided on the green sheet GS.

〔The invention's effect〕

As described above, according to the present invention, in the polishing layer of the ceramic substrate, in addition to the flatness adjustment allowance for adjusting the flatness and smoothness of the front and back surfaces, in order to adjust the parallelism of the front and back surfaces. Since the parallelism adjustment allowance and the thickness adjustment allowance are provided,
By polishing these in the order opposite to the stacking order, it is possible to highly accurately adjust the flatness of both the front and back surfaces, the parallelism, and the plate thickness dimension. As a result, after mounting the surface mount component, when the ceramic substrate is installed in the package of the refrigerant cooling method, the surface mount component can be brought into contact with the cooling piston with an appropriate contact pressure for efficient cooling, resulting in insufficient cooling and cooling. Impossible or damage to the surface mount component can be prevented.

In addition, the thickness of the thickness adjustment allowance, parallelism adjustment allowance, and flatness adjustment allowance should be set to the minimum necessary thickness to achieve the respective objectives of thickness adjustment, parallelism adjustment, or flatness adjustment. Therefore, the polishing time can be shortened to the necessary minimum.

Furthermore, according to the present invention, after providing a display means for displaying the stacking order on the green sheet to be stacked as the polishing layer,
Since the green sheets of each polishing layer are stacked in order according to the stacking order, the stacking order of the green sheets under polishing can be determined by looking at the display means of the green sheet on the polishing surface or the display means of the lower green sheet during polishing. It can be easily discriminated and it is possible to reliably prevent the pattern layer from being damaged by stopping the polishing before the polishing reaches the pattern layer.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a method for manufacturing a multilayer ceramic substrate according to an embodiment of the present invention, FIG. 2 is a plan view of the ceramic substrate being polished, and FIG. 3 is a water-cooling system for the multilayer ceramic substrate. It is a block diagram. In the figure, 1 ... Ceramic substrate, 2 ... Pattern layer, 3a ... Polishing layer, 3b
... polishing layer, 31a ... repolishing allowance, 31b ... repolishing allowance, 32 ... thickness adjustment allowance, 33a ... parallelism adjusting allowance, 33b ... parallelism adjusting allowance, 34a ...
Flatness adjustment allowance, 34a ... Flatness adjustment allowance, GS ... Green sheet, m ... Number.

Claims (1)

[Claims] 1. A polishing layer composed of a group of green sheets (GS), each of which is provided on the front surface side and the back surface side of a pattern layer (2) composed of a group of green sheets (GS) on which a required conductor pattern is formed. In the method for manufacturing a multilayer ceramic substrate in which (3a) and (3b) are laminated, front and back polishing layers (3a) and (3b)
A green sheet (GS) that serves as a thickness adjustment allowance (32) is laminated on one of the above, and each of the front and back polishing layers (3a) and (3b)
, A green sheet (GS) for adjusting the parallelism (33a) and (33b) and a green sheet (GS) for adjusting the flatness (34a) and (34b) are laminated, and each of the front and back polishing layers is laminated. (3a)
-Each green sheet (GS) stacked on (3b) is provided with a display means (m) for displaying the stacking order, and the green sheet (GS) of each polishing layer (3a) (3b) is stacked on the green sheet (GS). A method for manufacturing a multi-layer ceramic substrate, which comprises laminating the layers in order.