JPH10163358A - Base for ic package and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a package having a good isolation, compared with that in prior art by covering a metal film over the bottom and side face of a cavity for mounting an IC, wherein the package is provided with a plurality of signal lines and GND lines as well as the cavity. SOLUTION: The package has a cavity 12 for housing an IC, a plurality of signal lines 26 electrically connected to the IC and GND lines laid near the signal lines 26. A metal film 27 covers the bottom and side face of the cavity 12. A ceramic base 11 having a square groovy cavity 12, e.g. has a sputtered film 21 at the back side and a plurality of GND lines and signal lines 26 at the front side. It has a metal film 27 covering the cavity 12 of the base 11. The GND lines and signal lines 26 and metal film 27 are composed of a sputtered lower layer S and plated upper layer P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base used for, for example, an IC package or a thin film multilayer substrate (a substrate in which a plurality of wiring members and an insulating film covering the same are laminated), and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a base used for an IC package or a thin film multilayer substrate, for example, as shown in a sectional view of FIG. 7 and a plan view of FIG. A GND metal film 84 is formed, and a GND line 75 and a signal line 76 are formed on the surface of the base body 71.
And a GND 70 on which a sputtered film 81 is formed on the back surface of a base body 71 is known. The metal film 84 on the bottom surface of the cavity portion 82 was electrically connected to the sputtered film 81 by the inner layer via 83, and was electrically connected to the GND pad 79 by the inner layer via wiring 83 ′.

An example of a method for manufacturing such a conventional base 70 will be described with reference to FIG. First, an inner layer via 83 and an inner layer via wiring 83 'are provided, and a co-fire ink 84a, Ni-
Ceramic base body 7 with Au plating 84b
1 is prepared (see FIG. 9A).

Subsequently, a sputtered film 80 is formed on the surface of the base body 71 by sputtering (see FIG. 9B). Then, a photoresist is applied to the sputtered film 80, exposed and developed, and a GND line 75, a signal line 76,
Then, a resist 78 having a pattern covering portions other than the portion corresponding to the GND pad 79 is formed. And G
A portion corresponding to the ND line 75, the signal line 76, and the GND pad 79 is plated to form a plated portion 85 (FIG. 9).
(C)).

Thereafter, the resist 78 is peeled off, and the sputtered film 80 at the stripped portion is removed by etching to obtain a conventional base 70 (see FIG. 9D).

[0006]

However, in the conventional base 70, when an IC is mounted and operated in the cavity 82 in which the metal film 84 is formed only on the bottom surface,
In some cases, the isolation between input and output signals was not sufficient.

In the conventional base 70, the GND line 7
5 is connected to the metal film 84 on the bottom surface of the cavity part 82 by the inner layer via wiring 83 '. In this case, a GND pad 79 having a diameter larger than the diameter of the inner layer via wiring 83' is required. There is a disadvantage that the area occupied by the GND pad 79 is large and it is difficult to reduce the size.

Further, since the distance between the cavity 82 and the signal line 76 is long, the I
The length of the bonding wire joining the C and the signal line 76 is increased. For this reason, there is also a problem that the length of the mismatched line section becomes longer, which adversely affects the signal transmission characteristics.

In addition, since the electrical length between adjacent GNDs becomes longer, the adjacent signal lines 7 with the GND line 75 interposed therebetween
Signal line 7 has poor isolation between 6 and 76
There is a problem that a potential difference easily occurs between the GND lines 75 on both sides of 6 and the matching is easily lost.

Further, it is necessary to form a large number of inner via wirings 83 'around the cavity 82, which causes a problem that the number of steps is increased. The present invention has been made in view of the above problems. That is, the first aspect of the present invention aims to provide a base such as an IC package capable of improving the isolation better than the conventional one, and the second aspect of the present invention further makes it possible to further reduce the size and simplify the operation. IC that can be manufactured
The purpose is to provide a base such as a package. On the other hand, an object of the present invention is to provide a manufacturing method for easily manufacturing a base used for such an IC package or the like.

[0011]

Means for Solving the Problems and Effects of the Invention In order to solve the above-mentioned problems, a base used for an IC package or the like of the present invention comprises a cavity for mounting an IC,
A plurality of signal lines for electrical connection with C, and a GND line disposed in the vicinity of the signal line, wherein a bottom surface and side surfaces of the cavity are covered with a metal film. I do.

Such a base has a high shielding effect because not only the bottom surface but also the side surface of the cavity portion is covered with a metal film. Therefore, when the IC is mounted and operated in the cavity portion, compared with the conventional case, The effect that the isolation becomes better can be obtained. Here, it is preferable that the metal film covering the side surface of the cavity is connected to the GND line without passing through the inner layer. In this case, there is no need to provide a GND pad, so that the area occupied by the GND pad can be reduced, thereby achieving an effect that the size can be reduced and the distance between the cavity portion and the signal line can be reduced.
Further, since it is not necessary to provide the inner layer via wiring unlike the related art, the structure of the base body is simplified, and the effect that the base body can be easily manufactured is obtained.

The base of the present invention can be manufactured, for example, by a manufacturing method including the following steps. That is, a photoresist is applied to the surface of a base body having a cavity for mounting an IC, and is exposed and developed to form a resist having a predetermined pattern that does not cover at least the bottom and side surfaces of the cavity. Step (hereinafter, referred to as a first step), a step of providing a metal film on a portion not covered with a predetermined pattern of resist (hereinafter, referred to as a second step), and a step of removing the predetermined pattern of resist (hereinafter, referred to as a third step) ).

In the first step, the photoresist may be a negative resist or a positive resist. However, when a positive resist is used, the thickness of the positive resist applied to the side surface of the cavity becomes large in the vertical direction, so that this portion may not be sufficiently exposed and may remain after development. Therefore, it is preferable to use a negative resist that does not have such a risk. Before the photoresist is applied, a first metal film may be provided on the entire surface of the base body in advance by, for example, sputtering.

In the second step, the method of providing the metal film may be, for example, electroless plating if the first metal film is not provided, or the method of providing the first metal film. In such a case, electrolytic plating may be employed. However, when adopting the electroless plating, it is preferable to protect a portion that is not desired to be plated.

In the third step, the resist having a predetermined pattern is removed by, for example, peeling. When the first metal film is provided in the first step, thereafter, the portion of the first metal film from which the resist has been removed is removed by etching. Through the above steps, the base of the present invention is manufactured.

In consideration of the pattern accuracy and the number of steps,
It is preferable to use a negative resist for the photoresist. Further, it is preferable to form the first metal film by sputtering before applying the negative resist, and to form the second metal film by electrolytic plating.

The portions not covered with the resist having the predetermined pattern are the bottom and side surfaces of the cavity portion, a portion corresponding to a signal line discontinuous to the side surface, and a portion corresponding to a GND line continuous to the side surface. It is preferred that In this case, if the first to third steps are performed, not only a metal film is formed on the bottom surface and the side surface of the cavity portion,
Since the signal line and the GND line are also formed at the same time, the manufacture of the base is further simplified.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment of the present invention
It is needless to say that the present invention is not limited to the following embodiments, and can take various forms within the technical scope of the present invention.

In the following embodiments, a base used for an IC package will be described as an example. FIG. 1 is a cross-sectional view of the base of the present embodiment, FIG. 2 is a plan view of the base of the present embodiment, and FIG. 3 is an explanatory diagram of use when an IC is mounted on the base of the present embodiment. The base 10 includes a ceramic base body 11 having a square groove-shaped cavity 12, a sputtered film 21 provided on the back surface of the base body 11, and a plurality of base films provided on the surface of the base body 11. The semiconductor device includes a GND line 25, a signal line 26, and a metal film 27 covering the cavity 12 of the base body 11.

The GND line 25 is connected to a metal film 27 that covers the periphery 12c of the cavity 12. Therefore, the GND line 25 is connected to the metal film 27 covering the bottom surface 12 a and the side surface 12 b of the cavity 12 without passing through the inner layer of the base body 11.

The signal line 26 is connected to an IC mounted in the cavity 12 by a wire W,
It is arranged between the D lines 25. This signal line 26
Is the metal film 27 covering the cavity 12 or GND
It is not connected to the line 25. FIG. 2 shows the GND line 25.
Although the example in which one signal line 26 is provided between them is shown,
A plurality of signal lines 26,... May be arranged between the GND lines 25.

The metal film 27 is formed on the bottom surface 1 of the cavity 12.
2a, side surface 12b and periphery 12 of cavity 12
c. Each of the GND line 25, the signal line 26, and the metal film 27 has a two-layer structure, and includes a sputtering part S formed as a lower layer and a plating part P formed as an upper layer. In addition, the sputtering part S and the plating part P
For example, when the plating part P is copper-gold, the sputtering part S uses titanium-palladium.
The metal type of the sputter portion S is appropriately determined according to the metal type used for the sputtering.

The inner layer via 13 makes the metal film 27 covering the bottom surface 12a of the cavity 12 and the sputtered film 21 on the back surface of the base body 11 conductive. As shown in FIG. 3, an IC package manufactured using the base 10 having the above configuration
Is mounted, and the IC and the signal line 26 are joined by the wire W. Here, since the cavity 12 is covered not only with the bottom surface 12a but also with the side surface 12b with the metal film 27 as GND, the shielding effect is high. Therefore, when the IC is mounted on the cavity 12 and operated, As a result, the isolation becomes better and the stable operation of the IC is guaranteed.

The GND line 25 is connected to the cavity 12
Is connected to the metal film 27 covering the bottom surface 12a and the side surface 12b without passing through the inner layer of the base body 11, so that it is not necessary to provide the GND pad 79 (see FIG. 8) as in the related art. The occupied area can be reduced, which enables downsizing. Also,
Since it is not necessary to provide the inner layer via wiring 83 '(see FIG. 7) as in the conventional case, the structure of the base body 11 is simplified,
Can be easily manufactured.

For example, as shown in FIG. 4, the base main body 11 has a main body upper portion 11a having a hole 32 for forming the cavity portion 12, and a hole 3 for forming the inner layer via 13.
3 with the lower body 11b provided with
It can be manufactured by joining bodies.

Next, a method of manufacturing the base 10 of the present embodiment will be described with reference to FIG. FIG. 5 is a manufacturing process diagram of the base. First, sputtering is performed on the front and back surfaces of the base body 11 (see FIG. 5A) having the cavity portion 12 and the inner layer via 13 in the order of titanium and palladium,
The sputter films 20 and 21 are formed (see FIG. 5B).

Subsequently, a negative resist NR is applied to the entire surfaces of the sputtered films 20 and 21 covering the front and back surfaces of the base body 11 (see FIG. 5C). Here, the negative resist N
As is well known, R is a portion irradiated with light, which is insoluble in a developing solution due to a cross-linking reaction, whereby a negative resist pattern is formed.

For this reason, the mask M used for irradiating the front side of the base body 11 with light is composed of the bottom surface 12 a, the side surface 12 b and the periphery 12 c of the cavity 12, and the signal line 2.
6 (see FIG. 2) and a pattern corresponding to the GND line 25 (see FIG. 2) are formed so as not to irradiate light.

The front side of the base body 11 is exposed using the negative resist mask M (see FIG. 5D).
Note that the entire back surface of the base body 11 is irradiated with light. At this time, since the thickness of the portion of the negative resist NR irradiated with the light through the mask M is substantially uniform, the photocrosslinking reaction sufficiently proceeds. Although the thickness of the negative resist NR is large near the side surface 12b of the cavity portion 12, it is not irradiated with light but is eluted by a developing process described later, so that there is no possibility that the resist remains in the cavity portion 12.

Subsequently, the negative resist NR other than the portion irradiated with light by the developing solution is eluted. Then, a resist 23 having a predetermined pattern is formed on the surface of the base body 11 (see FIG. 5E). At this time, the portion not covered with the resist 23 of the predetermined pattern is the cavity portion 1
2, bottom surface 12a, side surface 12b and periphery 12c, and
A portion corresponding to the signal line 26 and a portion corresponding to the GND line 25. Note that the entire back surface of the base body 11 is covered with the resist 28.

Subsequently, electrolytic plating (copper-gold (surface layer is gold) or gold) is applied to the predetermined pattern (see FIG. 5 (f)). Then, a plated portion 24 is formed on the portion of the sputtered film 20 that is not covered with the resist 23 having the predetermined pattern. That is, the plating portion 24 is formed on the bottom surface 12a, the side surface 12b and the periphery 12c of the cavity portion 12, the portion corresponding to the signal line 26, and the portion corresponding to the GND line 25.

Then, after removing the resist 23, the sputtered film 20 at the portion where the resist 23 has been removed is removed by etching (see FIG. 5 (g)). Thereby, the base 10 of the present embodiment is manufactured. According to the above-described manufacturing method, not only the metal film 27 is formed on the bottom surface 12a, the side surface 12b, and the periphery 12c of the cavity portion 12, but also the signal line 26 and the GND line 25 are formed at the same time.
0 is easier to manufacture.

In the above-described manufacturing method, an example in which a negative resist is used as a photoresist has been described, but a positive resist may be used as a photoresist. However, considering the pattern accuracy and the number of steps, it is preferable to use the above-described negative resist rather than to use the positive resist. This will be described in detail below.

FIG. 6 is a diagram showing a pattern forming process in the case of using a positive resist. This process can be adopted instead of the pattern forming process shown in FIGS. 5 (c) to 5 (e). That is, the sputtered film 2 covering the front and back surfaces of the base body 11
A positive resist PR is applied to the entire surface of 0, 21 (FIG. 6)
(A)). Here, as is well known, the portion of the positive resist PR that has been irradiated with light is eluted into the developing solution due to the occurrence of a decomposition reaction, thereby forming a positive resist pattern.

For this reason, the mask M ′ used to irradiate the front side of the base body 11 with light corresponds to the bottom surface 12a, the side surface 12b and the periphery 12c of the cavity 12, and the signal line 26 (see FIG. 2). Portion, GND line 25 (FIG. 2
(See FIG. 3) is formed with a pattern for irradiating light.

The surface side of the base main body 11 is exposed using the positive resist mask M '(see FIG. 6B). The back side of the base body 11 is not irradiated with light. At this time, the thickness of the portion of the positive resist PR irradiated with light via the mask M ′ is not uniform, and the positive resist PR applied near the side surface 12 b of the cavity 12 is not uniform.
Is considerably thicker than the positive resist thickness a applied to the surface of the base body 11, and there is a possibility that the photodecomposition reaction does not sufficiently proceed. For this reason, the resist may remain in the cavity 12 after the development process is performed (see FIG. 6C).

As measures to avoid such a problem, that is, a problem that the resist remains in the cavity portion 12,
What is necessary is just to increase the amount of light to be irradiated or re-expose only the inside of the cavity portion 12. However, in the former case, the pattern accuracy may be affected, and in the latter case, the number of steps increases.

Therefore, using a negative resist as a photoresist makes it possible to obtain a resist of a predetermined pattern with high accuracy and with a short man-hour, as compared with the case of using a positive resist. That is, it is preferable to use a negative resist as the photoresist in consideration of the pattern accuracy and the number of steps.

In the above embodiment, the base used for the IC package has been described. However, a base having the same structure is used, for example, for a thin film multilayer substrate, that is, a substrate in which a plurality of wiring members and an insulating film covering the same are laminated. You may. In this case, the same effect as in the above embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a base according to the present embodiment.

FIG. 2 is a plan view of a base according to the present embodiment.

FIG. 3 is an explanatory diagram of use when an IC is mounted on a base of the embodiment.

FIG. 4 is an assembly view of the base body of the embodiment.

FIG. 5 is a manufacturing process diagram of the base of the present embodiment.

FIG. 6 is a diagram illustrating a pattern forming process when a positive resist is used.

FIG. 7 is a sectional view of a conventional base.

FIG. 8 is a plan view of a conventional base.

FIG. 9 is a manufacturing process diagram of a conventional base.

[Explanation of symbols]

10 ... base, 11 ... base body, 12 ...
Cavity part, 12a: bottom surface of cavity part, 12
b: side surface of cavity, 12c: periphery of cavity, 13: inner via, 20: sputtered film, 21: sputtered film, 23: resist, 24
... plating part, 25 ... GND line, 26 ... signal line, 27 ... metal film, 28 ... resist, M ...
Mask, NR: negative resist, PR: positive resist, P: plated part, S: sputter part.

Continuing on the front page (72) Inventor Takeshi Ohno 14-18, Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Inside Tokusatsu Tokusatsu Co., Ltd. (72) Inventor Toshikatsu 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Japan Hon Special Ceramics Co., Ltd.

Claims (7)

[Claims] A cavity for mounting an IC; a plurality of signal lines for electrically connecting to the IC; and a GND (ground) line disposed near the signal line. A base used for an IC package or the like, wherein a bottom surface and side surfaces of the cavity are covered with a metal film. 2. The base according to claim 1, wherein a metal film covering a side surface of the cavity is connected to the GND line without passing through an inner layer. 3. A resist having a predetermined pattern such that a photoresist is applied to the surface of a base body having a cavity for mounting an IC, and is exposed and developed so that at least the bottom and side surfaces of the cavity are not covered. Forming a metal film on a portion not covered with the predetermined pattern of resist, and removing the predetermined pattern of resist. 4. A step of providing a first metal film on the entire surface of a base body having a cavity for mounting an IC, applying a photoresist to the first metal film, exposing and developing the first metal film, and forming at least the cavity. Forming a resist having a predetermined pattern so as not to cover the bottom and side surfaces of the portion; providing a second metal film on a portion not covered with the resist having the predetermined pattern; removing the resist having the predetermined pattern; A method of manufacturing a base for use in an IC package or the like, comprising a step of removing the first metal film in a portion where the first metal film has been removed by etching. 5. The method according to claim 4, wherein the first metal film is formed by sputtering, and the second metal film is formed by electrolytic plating. 6. A portion not covered with the resist of the predetermined pattern corresponds to a bottom surface and a side surface of the cavity portion, a portion corresponding to a signal line discontinuous to the side surface, and a GND line continuous to the side surface. The method for producing a base according to any one of claims 3 to 5, wherein the base is a part to be formed. 7. The method according to claim 3, wherein the photoresist is a negative resist.