JP3279765B2 - Ceramic package - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package.

[0002]

2. Description of the Related Art Conventionally, various containers (semiconductor element packages) in which an IC chip or the like is mounted on an insulating substrate having a conductive circuit and the IC chip is hermetically sealed with a cap have been known. I have. In particular, in recent years, expectations for a so-called ceramic package in which a high heat conductive material such as an alumina substrate or an aluminum nitride substrate is used for an insulating substrate constituting the package have been particularly increased.

As this type of package, for example, a DIP (dual inline package) having a terminal on a side surface, a QFP (quad flat package),
PGA (Pin Grid Array) with terminals on the bottom
Etc. These packages are usually mounted on a printed wiring board made of resin or the like and used in a state where electrical connection with a conductor on the printed wiring board side is achieved.

[0004] Among the above-mentioned packages, the PGA type package employs a mounting method in which a large number of pins protruding from the lower surface side are inserted into through through holes on the printed wiring board side, which is the mounting side. The pin pitches are 2.54 mm (100 mil) and 1.27 mm (50 mil).
mil) has been the mainstream until now.

[0005]

In recent years, ICs have been developed.
As the functionality of the chip itself has become higher and more highly integrated, the number of pins on the package for mounting it has increased,
There is a demand for narrowing the pitch of the pins and wiring patterns (fining). Further, it is considered that such a reduction in the package size accompanying the finer wiring is preferable in reducing the manufacturing cost of a package using an expensive ceramic material.

However, when the pitch of the pins is reduced to 1.0 mm or less as a part of finer design, it is difficult to accurately form pins and form through holes, and it is extremely difficult to mount a package on a printed wiring board. Become.

Another problem is that there is a difference in the coefficient of thermal expansion between a package made of a ceramic material and a printed wiring board (a so-called motherboard) made of a resin material. For this reason, the pins and the wiring patterns may be affected by stress due to a change in ambient temperature or the like, and a defect such as a connection failure may occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to enable easy and reliable mounting on a printed wiring board, which is a motherboard, even when finer. It is an object of the present invention to provide a ceramic package which can reduce the influence of stress due to a temperature change and the like and can realize a low cost.

[0009]

In order to solve the above-mentioned problems, according to the present invention, there is provided a nitride semiconductor device for mounting a semiconductor device.
A ceramic wiring board made of luminium, and a mounting carrier having a plurality of metal leads radiating radially on at least one surface of a flexible resin base; The gist of the present invention is a ceramic package characterized in that it is a terminal for making electrical connection with the wiring board side, and the outer end of each metal lead is a leg for making electrical connection with the motherboard side. .

In this case, terminals may be provided on the conductor portion of the ceramic wiring board, and the terminals and the terminals on the respective metal leads may be joined via solder bumps, or the resin base may be in the form of a film. Further, a continuity inspection pad may be provided on the leg portion of the metal lead or on a portion on the outer end side of the leg portion.

[0011]

According to this structure, the conductor portion of the ceramic wiring board made of aluminum nitride is not directly connected to the conductor portion of the mother board on the mounting side.
The connection is made indirectly via the metal leads of the mounting carrier. For this reason, it is easy to cope with fineness, and even in such a case, there is no difficulty in mounting as in the case of using pins.

Further, according to this structure, the aluminum nitride
Even if there is a large difference in thermal expansion coefficient between the ceramic wiring board and the motherboard, the stress is buffered by the mounting carrier interposed between the ceramic wiring board and the motherboard, thereby preventing the occurrence of connection failure and the like.

In this case, it is desirable to provide a terminal on the conductor portion of the ceramic wiring board and join the terminal and the terminal of the metal lead via a solder bump. This bonding method generally does not require strict accuracy as compared with the case of pin bonding, and does not require pinning or the formation of through-holes on the substrate side. Therefore, this bonding method is suitable as a bonding method when a package is finer.

Further, it is desirable that the resin substrate is formed into a film shape. The reason is that such a shape increases the flexibility, so that the stress between the ceramic wiring substrate and the printed wiring board on the mounting side can be more reliably buffered.

Further, by providing a continuity inspection pad on the leg portion of the metal lead or on a portion on the outer end side of the leg portion, continuity inspection of the electronic component after mounting is facilitated.

[0016]

【Example】

[Embodiment 1] The present invention is described below with reference to aluminum nitride (Al)
An embodiment embodied in the ceramic package N) will be described in detail with reference to FIGS.

As shown in FIG. 5, the ceramic package 15 of the first embodiment mainly includes an AlN multilayer wiring board (hereinafter simply referred to as a multilayer board) 5 as a ceramic wiring board and the mounting carrier 1. .

First, the configurations of the mounting carrier 1 and the multilayer board 5 before joining will be described. As shown in FIG. 1, the mounting carrier 1 mainly includes a polyimide film 2 as a resin base, which is an insulator portion, and metal leads 4, which are conductor portions. The polyimide film 2 has a substantially square shape, and four trapezoidal holes 2b are provided at the outer edge thereof. A plurality of radially extending metal leads 4 are formed on one surface (the upper surface in this embodiment) of the polyimide film 2.

At the inner end of each metal lead 4, that is, at the end on the center side of the polyimide film 2, a square connection pad 4 a is provided as a terminal for making an electrical connection with the conductor on the multilayer board 5 side. Are formed. The connection pad 4a
As shown in FIG. 1, they are arranged at regular intervals on the upper surface of the polyimide film 2. On the other hand, the outer end of each metal lead 4, that is, the end on the outer edge side of the polyimide film 2 is a leg 4b for making an electrical connection with the motherboard 16 side. A solder resist 12 is formed on the upper surface of the polyimide film 2 in order to prevent a short circuit between the metal leads 4 due to the solder bumps 17 beforehand. As shown in FIG. 1, only the connection pad 4 a is exposed from the solder resist 12 in the covered inner end portion of the metal lead 4.

The outermost end of the metal lead 4 is a rectangular conduction test pad 4 used for a conduction test of the IC chip 9 or the like.
c. Note that the continuity inspection pad 4 of this embodiment is
c is the mounting carrier 1 when the printed wiring board 16 is mounted.
It is to be removed from.

Here, a general procedure for manufacturing the mounting carrier 1 of FIG. 1 will be described with reference to FIGS. 4 (a) to 4 (f). The mounting carrier 1 is produced using a polyimide film (trade name: IEL-L120) 2 having a thickness of about 100 μm as a starting material. This polyimide film 2
As shown in FIG. 4A, an adhesive layer B having a thickness of about 20 μm is previously formed on one surface of the substrate. Next, FIG.
As shown in (b), a trapezoidal hole 2b is formed at the outer edge of the polyimide film 2 by performing a router process. Next, as shown in FIG.
A copper foil C having a thickness of 35 μm is laminated on the surface having the adhesive layer B. Then, as shown in FIG. 4D, a dry film Df made of a photosensitive resin is further laminated on the surface of the copper foil C. Further, by applying a liquid resist Lr to the back side of the polyimide film 2, the trapezoidal holes 2 are formed.
b is provisionally filled in.

Here, after exposing and developing by arranging a mask (not shown) on the dry film Df, the copper foil C is partially treated by treating the copper foil C with an etching solution capable of dissolving copper. Remove. After this step, a metal lead 4 having a connection pad 4a, a leg 4b, and a continuity test pad 4c is formed on a predetermined portion of the polyimide film 2. Thereafter, as shown in FIG. 4E, the unnecessary dry film Df and liquid resist Lr are peeled off from the metal leads 4. Further, by applying a solder resist 12 on the upper surface of the polyimide film 2 and performing exposure and development, an opening is formed in a portion of the connection pad 4a as shown in FIG. Through the above procedure, the mounting carrier 1 is obtained.

As shown in FIGS. 2 to 4, an IC chip 9 as a semiconductor element is mounted at the center of the upper surface of the multilayer board 5. Such a multilayer board 5 can be obtained, for example, by laminating green sheets on which a conductive paste is printed, and then firing the laminated body under high-temperature conditions. A plurality of through holes 8 are formed in the multilayer board 5. The bonding pad 6 is joined to the upper opening of the through hole 8. Bonding pad 6 and bonding pad on IC chip 9 side (not shown)
Is bonded via the gold wire 10.
The wire-bonded IC chip 9 is hermetically sealed by an AlN cap 11 which is slightly larger than that.

At the lower opening of the through hole 8, a connection pad 7 as a terminal used at the time of bonding with the mounting carrier 1 is bonded. The connection pads 4a on the mounting carrier 1 side and the connection pads 7 on the multilayer board 5 have the same number and a positional relationship corresponding to each other.

As shown in FIG. 5, the mounting carrier 1
Is mounted on the lower surface of the multilayer board 5. The connection between the connection pads 4a and 7 is performed by reflowing the solder bumps 17 provided on the connection pads 7 of the multilayer board 5 in advance. As a result, the metal leads 4 on the mounting carrier 1 and the conductors on the multilayer board 5 are electrically connected via the solder bumps 17. After this,
The mounting carrier 1 is cut at a predetermined position (the position indicated by the broken line in FIG. 4F) by processing using a mold or the like, and the continuity inspection pad 4c is removed from the mounting carrier 1. At this time, the leg 4b of each metal lead 4 is bent in a gull wing shape by the mold.

The ceramic package 15 obtained as described above is used while being mounted on a motherboard (a printed wiring board made of epoxy resin or the like in this embodiment) 16. At this time, as shown in FIG. 5, the bent leg portion 4b and the conductor pattern 16 on the motherboard 16 side are used.
a is joined by soldering or the like.

Now, according to the configuration of the present embodiment, the multilayer board 5
The conductor portion on the side is the conductor pattern 1 on the motherboard 16 side.
6a is not directly connected. That is,
The conductor portion is indirectly connected to the conductor pattern 16a via the metal leads 4 which spread radially from the periphery of the mounting carrier 1. Therefore, unlike the conventional ceramic package, it is not necessary to set up a large number of pins in a narrow space or to provide a large number of through-holes for mounting pins on the motherboard 16 side.
Therefore, the problems which have conventionally been barriers to finer design can be solved.

As a result, it is possible to increase the number of connection pads 4a and 7 and to reduce the pitch of the connection pads 4a, 7 and the like. Further, according to the joining method using the solder bumps 17 as in the embodiment, there is an advantage that strict dimensional accuracy is not required as in the conventional joining method of inserting a pin into a through-hole.
For this reason, even when the fine ceramic package 15 is mounted on the motherboard 16, the mounting operation can be performed more easily and reliably than in the related art.

Further, according to the structure of the embodiment in which the continuity inspection pad 4c is provided on the mounting carrier 1, the connection pad 4
Even if the number of a and 7 is increased or the pitch is narrowed,
There is an advantage that a continuity test or the like can be performed independently of them.

In this embodiment, a polyimide film 2 having excellent flexibility is selected as a resin base constituting the mounting carrier 1. For this reason, even if the difference in thermal expansion coefficient between the multilayer board 5 and the motherboard 16 is large, the stress caused by a change in ambient temperature or the like is buffered by the mounting carrier 1 interposed therebetween. As a result, it is possible to prevent the occurrence of connection failure or the like beforehand. In addition, with such a film-like material, there is no disadvantage that the thickness or the cost of the ceramic package 15 is increased. Second Embodiment Next, a ceramic package 20 according to a second embodiment will be described in detail with reference to FIGS.

FIG. 6 shows a mounting carrier 21 constituting the ceramic package 20 together with the multilayer board 5. The mounting carrier 21 of the present embodiment has a common feature with the first embodiment in that a plurality of metal leads 4 are formed on one surface of the polyimide film 2 and spread radially. In addition, the connection pad 4a, the leg 4b, the continuity inspection pad 4
Since c, the shape and arrangement of the trapezoidal holes 2b are basically the same as those in the first embodiment, detailed description thereof is omitted here.

In the case of this mounting carrier 21, the metal leads 4 are arranged on the lower surface of the polyimide film 2 as shown in FIG. This is a major difference from the configuration of the mounting carrier 1 according to the first embodiment. Therefore, the polyimide film 2 of the mounting carrier 21
Is not formed with a solder resist 12 for preventing short circuit. Further, in the portion of the polyimide film 2 where the connection pads 4a are formed, a plated through hole 22 penetrating through the front and back of the polyimide film 2 is formed. That is, in the case of the mounting carrier 21 in which the connection pad 4a is on the lower surface side, the upper opening 22a of the plated through hole 22 substantially functions as a connection terminal.

Since the mounting carrier 21 of FIG. 6 has the same basic structure as the mounting carrier 1 of the first embodiment, it is manufactured basically according to the procedure shown in the first embodiment. be able to. However, in the case of the present embodiment, a hole making step for forming the plated through hole 22 and an electroless copper plating step for that part are required. Further, the step of forming the solder resist 12 becomes unnecessary.

As shown in FIG. 8, the mounting carrier 2
1 is attached to the lower surface of the multilayer board 5. The connection between the connection pad 4a and the upper opening 22a of the plated through hole 22 is performed by reflowing a solder bump 17 previously provided on the connection pad 7 of the multilayer board 5. As a result, the metal leads 4 on the mounting carrier 21 side and the conductor portions on the multilayer board 5 side are electrically connected via the solder bumps 17. Thereafter, the mounting carrier 21 is cut at a predetermined position (the position indicated by the broken line in FIG. 7) by processing using a mold or the like, and the continuity inspection pad 4c is removed from the mounting carrier 21. At this time, the leg 4b of each metal lead 4 is bent in a gull wing shape by the mold. The bent leg 4b is connected to the motherboard 1
The conductor pattern 16a on the sixth side is joined by solder or the like.

Now, according to the configuration of this embodiment, the multilayer board 5
The conductor portion on the side is the conductor pattern 1 on the motherboard 16 side.
It is not directly connected to 6a, but is indirectly connected via the metal leads 4 spread radially in all directions. Therefore, as in the case of the first embodiment, various problems in the related art (e.g., setting up a large number of pins in a narrow space, providing a large number of through-holes for mounting pins on the motherboard 16 side).
Is eliminated. As a result, an increase in the number of connection pads 4a and 7 and a reduction in the pitch thereof can be realized, and a reduction in manufacturing cost can be achieved.

Further, according to the structure of the present embodiment, strict dimensional accuracy is not required as compared with the conventional case, so that the operation of mounting the fine ceramic package 20 on the motherboard 16 becomes easy and reliable. Further, the provision of the continuity inspection pad 4c facilitates continuity inspection when the pitch is reduced.

Since the polyimide film 2 having excellent flexibility is used for the mounting carrier 21, the stress caused by the difference in thermal expansion coefficient between the multilayer board 5 and the motherboard 16 is also reliably buffered. You. As a result, the occurrence of a connection failure or the like is prevented. Moreover, such a film-shaped one does not have the disadvantage of increasing the thickness or the cost of the ceramic package 20.

In the case of the mounting carrier 21 according to the second embodiment, since the metal leads 4 are not arranged on the multilayer board 5 side, there is an advantage that a short circuit due to the reflow of the solder bumps 17 hardly occurs. Therefore, the solder resist 12 for preventing a short circuit becomes unnecessary.
For this reason, it becomes possible to make the manufacturing cost even easier than in the first embodiment.

The present invention is not limited to the configurations of the first and second embodiments, but can be changed to the following configurations .

(B) When the ceramic wiring board 5 is mounted on the upper surface side of the mounting carrier 1, not only a so-called face-up type but also a face-down type as in the first and second embodiments. It is also possible to adopt a method in which the ceramic wiring substrate 5 is mounted on the motherboard 16 while being mounted on the lower surface side of the mounting carrier 1.

(C) The present invention can be embodied as a multi-chip module in which a plurality of IC chips 9 are mounted on one ceramic wiring board 5. Further, it is needless to say that the present invention can be embodied in a ceramic package in which semiconductor components other than the IC chip 9 are mounted and sealed.

(D) The solder bumps 17 are placed on the connection pads 4a on the mounting carrier 1 side or on the mounting carriers 21.
May be provided on the upper opening 22a of the plating through hole 22 on the side.

(E) As a metal other than solder, for example, gold may be used to form bumps. In joining the connection pads 4a and 7 or joining the connection pad 4a and the upper opening 22a, a joining method other than a bump may be adopted.

(F) The resin substrate 2 is not limited to the polyimide film 2 shown in the embodiment, but may be, for example, a film made of epoxy or other resin. Also, the shape is not limited to the film shape, but may be changed to another shape such as a plate shape. In addition, as long as the material has a certain degree of flexibility, the material thereof can be appropriately changed.

The film-shaped mounting carriers 1 and 2
As 1, it is preferable to use, for example, a well-known TAB tape which is long and continuous, and in which a sprocket hole is formed. Use of such a TAB tape-like mounting carrier is convenient for automation and the like. In addition, it is also possible to use a printed wiring board having a lead frame as the resin base 2.

(G) The ceramic wiring board 5 is not limited to a multilayer board as in the first and second embodiments, but may be a double-sided board. (H) The shape of the cap 11 is not limited to those of the first and second embodiments. For example, the ceramic wiring board 5
In the case where a cavity for accommodating the IC chip 9 is formed substantially at the center of the device, it may be sealed with a plate-like cap. In this case, resin sealing may be employed instead of cap sealing.

(I) Of course, the motherboard 16 on which the ceramic packages 15 and 20 of the present invention are to be mounted is not necessarily limited to the printed wiring board 16 made of resin. For example, a wiring board in which a conductor pattern is printed on a ceramic sintered body or a metal plate such as aluminum may be used.

In this case, if the coefficient of thermal expansion of the ceramic wiring board on the mounting side is different from the coefficient of thermal expansion of the ceramic wiring board 5, the above-described motherboard 1
As in the case of 6, the stress due to the difference in thermal expansion coefficient is buffered.

(J) In forming the metal lead 4,
Of course, a metal foil other than a copper foil may be used. In the metal lead 4, other than the portion that becomes the leg 4 b (the connection pad 4
For example, a) can be formed by printing or plating a conductive metal paste such as a tungsten paste.

(K) The metal leads 4 may be provided on both sides of the polyimide film 2. With such a configuration, a high-density ceramic package can be realized by combination with the finer ceramic wiring board 5. That is, with this configuration, the connection pads 4
This is because a large number of a and the upper opening 22a of the plated through hole 22 can be provided on the entire surface of the polyimide film 2.

(L) A plurality of ceramic multilayer substrates 5
A method of mounting the motherboard 16 on the mounting carriers 1 and 21 may be adopted. (M) In the case of employing the configuration of the second embodiment, it is not always necessary to completely fill the plated through hole 22 with electroless copper plating, and for example, a state may be left in which some gaps are left in the plated through hole 22. In this case, it becomes easy to control the amount of the solder bumps 17 when joining by reflow.

(N) When the configuration of the mounting carrier 21 of the second embodiment is adopted, the following configuration may be used. For example, as in another example 1 shown in FIG. 9A, each conduction inspection pad 4 c may be exposed on the upper surface side by providing a window 23 on the outer peripheral portion of the polyimide film 2. Further, as in another example 2 shown in FIG. 9B, the continuity inspection pad 24 may be provided on the leg portion 4b of the metal lead 4 itself. With the above configuration, the continuity test can be performed from the upper surface side, which is convenient.

[0053]

As described above in detail, according to the ceramic package of the present invention, an excellent effect that it can be easily and reliably mounted on a printed wiring board as a mother board even when it is made finer. Play. Moreover, according to the ceramic package of the present invention, the effects of stress due to a temperature change or the like can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a mounting carrier according to a first embodiment.

FIG. 2 is a plan view showing an AlN multilayer wiring board.

FIG. 3 is a bottom view of the AlN multilayer wiring board of FIG. 2;

FIGS. 4A to 4F are front cross-sectional views for explaining a procedure for manufacturing the mounting carrier of FIG. 1;

FIG. 5 is a partial schematic front sectional view showing a state where the ceramic package of the first embodiment is mounted on a motherboard.

FIG. 6 is a plan view showing a mounting carrier according to a second embodiment.

FIG. 7 is a front sectional view showing the mounting carrier of FIG. 6;

FIG. 8 is a partial schematic front sectional view showing a state in which the ceramic package of Example 2 is mounted on a motherboard.

FIG. 9A shows a mounting carrier of another example 1,
(B) is a partial enlarged plan view showing a mounting carrier of another example 2.

[Explanation of symbols]

1, 21 ... mounting carrier, 2 ... polyimide film as resin base, 4 ... metal lead, 4 a ... connection pad as terminal, 4 b ... leg, 4 c, 24 ... continuity inspection pad, 5 ... ceramic wiring board AlN multilayer wiring board (= multilayer board), 7... Connection pads as terminals,
9: IC chip as semiconductor element, 16: motherboard, 17: solder bump.

Claims (4)

(57) [Claims] 1. An aluminum nitride for mounting a semiconductor element.
And a mounting carrier having a plurality of metal leads extending radially on at least one surface of a flexible resin base, and an inner end of each of the metal leads is formed of the ceramic wiring board. A ceramic package comprising: terminals for making an electrical connection to a wiring board; and outer ends of the metal leads serving as legs for making an electrical connection to a motherboard. 2. The method according to claim 1, wherein a terminal is provided on a conductor portion of the ceramic wiring board, and the terminal and the terminal on each of the metal leads are joined via a solder bump.
The ceramic package according to 1. 3. The ceramic package according to claim 1, wherein said resin base is in the form of a film. 4. The ceramic according to claim 1, wherein a continuity inspection pad is provided on a leg portion of the metal lead or on a portion on an outer end side of the leg portion. package.