JP2001244578A - Multilayer substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer substrate in which deformation to be generated in the firing of substrate can be evaded by a simple structure. SOLUTION: A multilayer substrate 10 is constituted by stacking a green sheet 14 whose central part is opened on a laminate of planar green sheets 12 and further laminating a green sheet 16 having an aperture area larger than that of the green sheet 14, and is provided with a cavity 11 for mounting a flip chip IC. Electrode pads 18 for connecting the flip chip IC are arranged in the peripheral part of the aperture of the green sheet 14, and the flip chip IC is connected with the pad 18. Since the green sheet 14 has the aperture, a gap is formed between the flip chip IC and the green sheet 12. When a warpage is caused in the firing of the substrate, the central part of the substrate does not come into contact with the flip chip IC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated substrate,
More specifically, the present invention relates to a laminated substrate having a cavity for mounting a semiconductor chip.

[0002]

2. Description of the Related Art An alumina ceramic substrate used for a semiconductor device such as an IC chip is manufactured, for example, as follows. First, a conductive pattern is formed by printing a paste of a high melting point metal such as tungsten or molybdenum on a plurality of ceramic green sheets, and then these green sheets are laminated and pressed to form a laminated structure. Next, this is fired at about 1500 to 1600 ° C., and a conductor on the surface of the substrate is subjected to gold plating or the like as necessary, thereby completing an alumina ceramic substrate.

In the firing step, the alumina ceramic substrate is shrunk and shrunk according to the plastic properties of the green sheet. At this time, if the firing shrinkage ratios are partially different, the fired substrate is warped and deformed. Particularly, in the case of a laminated substrate, the conductor pattern inside the substrate and the firing shrinkage ratio of the ceramic are different, so that deformation is more likely to occur.

For this reason, conventionally, as shown in FIG.
The load plate 1 is placed on the ceramic substrate 102 placed on the table 100.
By sintering the ceramic substrate 102 while holding the substrate 04 thereon, the warpage of the substrate was suppressed.

However, according to this method, a cavity (recess) 1 for mounting a component as shown in FIG.
In the case of the ceramic substrate 102 provided with No. 06, since the load of the load plate 104 is not applied to the portion of the cavity 106, the warpage of the bottom surface of the cavity cannot be suppressed.

When a semiconductor having a so-called flip-chip structure in which bump electrodes are arranged on the periphery of a chip is connected to the warped ceramic substrate, the connection of components may be adversely affected. That is, FIG.
As shown in the figure, when the flip chip IC 108 is mounted on the ceramic substrate 102 having no warp, the bump electrode 110 is securely connected to the ceramic substrate 102.
As shown in FIG. 11B, when the flip chip IC 108 is mounted on the warped ceramic substrate 102, the outer bump electrodes 110 may float, and the connection to the ceramic substrate 102 cannot be reliably performed. There is.

Even if the warpage of the ceramic substrate 102 is small and the bump electrode 110 can be connected to the ceramic substrate 110, the gap between the center portion of the flip-chip IC 108 and the ceramic substrate is narrowed. The fluidity at the time of filling the underfill resin in the step becomes poor. For this reason, the filling time becomes long, and in the worst case, the resin does not flow.

For example, the outer dimensions are 25 × 30 mm, the thickness is 1.8 mm, and the center is 15 × 15 mm and the depth is 0.
When the applicant measured the warpage of the cavity portion of the alumina substrate having a 7 mm cavity,
In an area of 10 × 10 mm, a convex warpage was generated on the upper side by a maximum of about 30 μm.

In this case, the height (diameter) of the bump is 30 μm.
If it is less than m, the chip surface and the substrate come into contact with each other, and it becomes impossible to reliably connect the chip to the substrate. In addition, when the present applicant conducted an experiment on a chip having bumps with a bump height of about 50 μm, the chip surface did not come into contact with the substrate. It turned out that the sex worsened.

To solve this problem, Japanese Patent Application Laid-Open No. 9-20 / 1990
Japanese Patent Application Laid-Open No. 2665 and Japanese Patent Application Laid-Open No. H11-195726 disclose a technique in which a load plate for applying a load to a cavity portion is prepared to suppress the warpage of the substrate.

Japanese Patent Application Laid-Open No. H11-177238 discloses that a cavity material is filled with a paste material having a sintering temperature higher than a substrate sintering temperature and taking into account a shrinkage rate during sintering of a ceramic substrate, and then a flat plate is formed on the paste material. A technique for applying a load is disclosed.

[0012]

However, in the techniques described in Japanese Patent Application Laid-Open Nos. 9-202665 and 11-195726, load plates are individually provided in accordance with the dimensions (size, depth) of the cavity. Therefore, there is a problem that the number of steps of the manufacturing process such as switching of the load plate is increased and the cost is increased.

The technique described in Japanese Patent Application Laid-Open No. H11-177238 has a problem that a new process and a new material are required, and that selection of a material is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a laminated substrate capable of avoiding deformation caused by firing a substrate with a simple structure.

[0015]

In order to achieve the above object, the invention according to claim 1 is characterized in that a first layer is laminated on the first layer, the first layer has a first opening, and the first layer has a first opening. A second layer in which an electrode for connecting a semiconductor chip is arranged around the first opening, and a second opening having an area larger than a region in which the first opening and the electrode are arranged. And the second layer is stacked on the second layer such that the first opening is located substantially at the center of the second opening and the electrode is located at an edge of the second opening. A third layer,
It is characterized by having.

The first layer is composed of a green sheet of, for example, alumina ceramic. The second layer is, for example, similarly formed of a green sheet of alumina ceramic or the like, and is laminated on the first layer.

Further, the second layer has a first opening, and an electrode for connecting a semiconductor chip is provided around the first opening. The shape of the first opening is, for example, rectangular, and can be substantially the same as the outer shape of a semiconductor chip to be mounted, for example, a semiconductor chip having a flip chip structure provided with bump electrodes.

The third layer, like the first and second layers, is made of a green sheet of alumina ceramic or the like, and is larger than, for example, the total area of the first opening and the region where the electrodes are arranged. It has a second opening of area. The shape of the second opening is, for example, substantially the same as that of the first opening, and is preferably substantially the same as the outer shape of the semiconductor chip to be mounted.

The third layer is formed such that the first opening is located substantially at the center of the second opening and the electrode is located at the edge of the second opening. Laminated. That is, the electrode and the first opening are stacked on the second layer so as to be located in the second opening. It is preferable that the depth of the second opening is equal to or larger than the height of the semiconductor chip. Thus, when the semiconductor chip is mounted on the electrode, the semiconductor chip can be prevented from protruding above the first layer.

As described above, the first opening and the second opening provided in the second layer and the third layer constitute a cavity for mounting a semiconductor chip. Also,
Since the first opening is provided in the second layer on which the electrodes are arranged, a gap is formed below the semiconductor chip when the semiconductor chip is mounted. The depth of the first opening is set in consideration of the influence of warpage generated when a load plate is placed on the third layer and fired. That is, the depth of the first opening is set so that the first layer does not contact the semiconductor chip when warpage occurs.

When firing such a laminated substrate, a flat load plate is placed on the third layer and fired. At this time, since the electrode for connecting the semiconductor chip is provided around the second opening in the third layer, the electrode is easily affected by the load from the load plate, and warpage is less likely to occur. Therefore, the bump electrodes of the semiconductor chip can be prevented from floating, and the semiconductor chip and the electrodes can be reliably connected.

Further, since the first opening is provided, the lower side of the semiconductor chip is one step lower than the position where the electrode is provided. Does not come into contact with the first layer. For this reason, it is possible to prevent deterioration in fluidity when filling the underfill resin.

In the case where a plurality of semiconductor chips are mounted, the first opening and the second opening, that is, the cavity, are provided in accordance with the number of mounted semiconductor chips. May be provided. in this way,
By providing a cavity for each semiconductor chip, when the load plate is placed on the third layer during firing, the contact area between the load plate and the third layer increases, and a load is more easily applied. Therefore, the warpage of the substrate can be further suppressed.

Further, at least one notch may be provided around the second opening. By providing the notch around the second opening as described above, it becomes easier to fill the underfill resin, so that the working efficiency and the production efficiency can be improved.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described.

FIG. 1 shows a multilayer substrate 10 as a laminated substrate.
It is shown. As shown in FIG. 1A, a multilayer substrate 10 is formed by stacking a plurality of flat green sheets 12, for example, as shown in FIG. 1A, and a green sheet 14 having a central opening as shown in FIG. Laminate and then Figure 1
The configuration is such that green sheets 16 having an opening area larger than the opening area of the green sheet 14 as shown in FIG.

The green sheets 12, 14, 16
Are made of, for example, alumina ceramic, and all have the same thickness as an example.

As described above, the multilayer substrate 10 is formed by laminating the green sheets 14 and 16 having openings, thereby forming a cavity 1 for mounting a flip-chip IC.
1 are formed.

Further, an electrode pad 18 for connecting a flip chip IC is provided around the opening of the green sheet 14 as shown in FIG. The bump electrode 22 of the flip chip IC 20 is connected to the electrode pad 18 as shown in FIG. 3, and the flip chip IC 20 is mounted in the cavity 11.

The shape of the opening of the green sheet 16 is similar to, for example, the shape of the flip-chip IC 20, and its outer dimensions are larger than the outer dimensions of the flip-chip IC 20, and are stacked below the green sheet 16. The size is such that all the electrode pads 18 provided around the opening of the green sheet 14 are exposed.

The thickness of the entire green sheet 16 is as follows:
The thickness of the flip chip IC including the bump electrodes 22 is made equal to or larger than that of the flip chip IC, and the thickness of the electrode pad 18 is made as thick as possible. Therefore, the flip chip IC 20 can be mounted in the cavity 11 without protruding above the green sheet 16. The depth of the cavity 11 is, for example, several μm to
It can be easily adjusted by changing the number of stacked green sheets 14 and 16.

A method for manufacturing such a multilayer substrate 10 will be described.

First, one or a plurality of green sheets 12 are laminated and pressed. Next, green sheet 14 is placed on top
Are laminated and pressed, and one or more green sheets 16 are further laminated thereon and pressed.

Next, the green sheets laminated and pressed as described above are placed on a table 24 as shown in FIG. 4, and a flat load plate 26 is placed thereon. Then, firing is performed at a predetermined temperature in this state. Thereby, the multilayer substrate 10 is completed.

Then, the flip chip IC 20 is mounted on the multilayer substrate 10 as shown in FIG. At this time, the electrode pad 18 to which the bump electrode 22 of the flip chip IC 20 is connected is provided near the opening of the green sheet 16 on which the load plate 26 is placed. Warpage is reduced. For example, when the applicant measured the warpage of the side surface of the cavity, that is, the portion on the inner side (center side) of about 3 mm from the edge of the opening of the green sheet 16 with respect to the alumina substrate having the above-described external dimensions, the warp was about 10 μm or less, and the height of the bump was about It was small enough.

As described above, the electrode pad 18 to which the bump electrode 22 of the flip chip IC 20 is connected is provided in the vicinity of the opening of the green sheet 16, that is, in the portion where the warpage is small due to the effect of the load by the load plate 26. The flip-chip IC 20 is mounted on the multilayer substrate 1
It can be mounted with a connection quality stable to zero.

The central portion of the cavity 11 which is not affected by the load by the load plate 26
8 is one step lower than the part provided.
Therefore, as shown in FIG. 5, even if warpage occurs to some extent, it does not come into contact with the flip chip IC 20. Therefore, a gap between the multilayer substrate 10 and the flip-chip IC 20 can be ensured, and after the flip-chip IC 20 is mounted, fluidity at the time of filling the underfill resin for the purpose of protecting components can be ensured.

[Second Embodiment] Next, a second embodiment of the present invention will be described.

In the second embodiment, a multi-layer board for mounting a plurality of components will be described. The same parts as those of the multilayer substrate 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 6 and 7, the multilayer substrate 10 comprises:
A plurality of cavities 11 according to the number of parts to be mounted (FIG. 6)
2). By providing the cavities 11 in accordance with the number of components as described above, the contact area between the load plate 26 and the multilayer substrate 10 increases, so that a sufficient load is applied to the multilayer substrate 10. As a result, the warpage of the substrate can be significantly suppressed as compared with the case where a plurality of components are mounted in one cavity.

[Third Embodiment] Next, a third embodiment of the present invention will be described.

In the third embodiment, a description will be given of a multi-layer substrate which further improves the fluidity when filling an underfill resin after mounting components. The multilayer substrate 1 shown in FIG.
The same parts as those of 0 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 8, the multilayer substrate 10 has a notch at the outer edge of the cavity 11, that is, at the inner edge of the opening of the green sheet 16, in which an injection nozzle (not shown) for injecting an underfill resin is inserted. At least one portion 28 (two portions in FIG. 8) is provided.

At the time of filling the underfill resin, the underfill resin is filled from the two cutouts 28, so that air bubbles are generated in the gap between the flip chip IC 120 and the multilayer substrate 20 '' by the osmotic pressure. In this way, by filling the underfill resin from the plurality of notches 28, the working efficiency and the production efficiency can be improved.

[0045]

As described above, according to the first aspect of the present invention, the electrode for connecting the semiconductor chip is the third electrode.
Is provided at the edge of the second opening of the second layer, so that it is susceptible to the load from the load plate and is less likely to warp, thereby preventing the bump electrodes of the semiconductor chip from floating. The semiconductor chip and the electrode can be reliably connected, and the lower side of the semiconductor chip is further lowered, so that even if warpage occurs, the semiconductor chip does not contact the first layer, It can prevent deterioration of fluidity when filling the underfill resin,
It has the effect of.

According to the second aspect of the present invention, since the first opening and the second opening are provided in accordance with the number of semiconductor chips to be mounted, the load plate is formed on the third layer when firing. When it is placed, the contact area between the load plate and the third layer is increased, and a load is more likely to be applied, so that there is an effect that the warpage of the substrate can be further suppressed.

According to the third aspect of the present invention, at least one notch is provided around the first opening, so that the underfill resin can be easily filled, and the working efficiency and the production efficiency are improved. This has the effect of being able to

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view of a multilayer substrate according to a first embodiment.

FIG. 2 is a plan view of the multilayer substrate according to the first embodiment.

FIG. 3 is a cross-sectional view of the multilayer substrate according to the first embodiment.

FIG. 4 is a diagram for explaining firing of the multilayer substrate according to the first embodiment.

FIG. 5 is a diagram for explaining a multilayer substrate in which warpage has occurred.

FIG. 6 is a diagram for explaining firing of a multilayer substrate according to a second embodiment.

FIG. 7 is a perspective view of a multilayer substrate according to a second embodiment.

FIG. 8 is a perspective view of a multilayer substrate according to a third embodiment.

FIG. 9 is a view for explaining a conventional firing of a multilayer substrate.

FIG. 10 is a view for explaining a conventional firing of a multilayer substrate.

FIG. 11 is a view for explaining a conventional multilayer substrate in which warpage has occurred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Multilayer board 12 Green sheet (1st layer) 14 Green sheet (2nd layer) 16 Green sheet (3rd layer) 18 Electrode pad 20 Flip chip IC 22 Bump electrode 24 26 Load plate 28 Notch

Claims (3)

[Claims] A first layer, a first layer laminated on the first layer, having a first opening, and an electrode for connecting a semiconductor chip around the first opening, the first layer being disposed on the first layer; A second opening having a larger area than a region in which the first opening and the electrode are arranged, and the first opening substantially in the center of the second opening. And a third layer laminated on the second layer such that the electrode is located at an edge of the second opening. 2. The laminated substrate according to claim 1, wherein said first opening and said second opening are provided in accordance with the number of semiconductor chips to be mounted. 3. The apparatus according to claim 1, wherein at least one
3. The laminated substrate according to claim 1, wherein two notches are provided.