JP3105362B2 - High density IC package and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density IC package and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, a high-density IC package has a multi-layer wiring structure. First, a metal paste such as tungsten W or molybdenum Mo is screen-printed in a predetermined pattern on the surfaces of a plurality of green sheets mainly composed of ceramics such as alumina to form a wiring pattern. A conductive via for interconnecting each wiring of the printed green sheet is punched out, and the via is filled with a metal paste. Also, some green sheets are stamped with an opening serving as an IC storage space. However, the punching process and the printing process may be performed before and after.

In the vicinity of the opening on the main surface of the green sheet, which is the uppermost layer, a power supply or grounding pad connected to either the power supply wiring or the ground wiring among the internal wirings, a signal pad connected to the signal wiring and Resistor pads to be connected to the terminating resistors are printed in a position corresponding to each pad on the IC with a metal paste. On the other hand, on the surface or side surface of the green sheet, a braze pad for brazing metal pins for connection to an external circuit is printed with a metal paste. And these green sheets are laminated,
After the thermocompression bonding, it is fired at a high temperature of about 1500 degrees to form a multilayer wiring board.

Next, at the periphery of the main surface of the multilayer wiring board,
A sealing frame made of ceramics or Kovar is brazed to a brazing pad and a metal pin is silver-brazed.
Thus, the IC package is completed for the time being, the wiring pattern becomes a power wiring, a ground wiring or a signal wiring, and the bottom surface of the opening becomes a die attach portion for mounting the IC.

After the IC is mounted on the die attach portion, the power supply pad, the grounding pad, and the signal pad are wire-bonded to the pads on the IC corresponding to each of the power supply pad, the grounding pad, and the signal pad, so that the signal is applied to 50Ω or the like. In the case of wiring that needs to be terminated with a wire, the signal pad and the resistor pad are further wire-bonded. Finally, the cap made of ceramics or Kovar, by seam welding or low melting glass bonding to the sealing frame,
The IC is hermetically sealed in the package.

[0006]

As described above, when the power supply pad, the ground pad, and the signal pad are formed at positions corresponding to the pads on the IC corresponding to each of them, the product numbers change. In each case, the screen mask for printing must be changed, which significantly increases the cost for a variety of small-quantity products and test products.

In recent years, the density of wirings and the miniaturization of devices have been increasing, and especially in the pad portion where wirings are concentrated,
It has become difficult to meet the demand for finer wiring by a thick film forming method such as printing.

The present invention has been made in such a situation, and its object is to firstly reduce the production cost by unifying the pad forming process and the device therefor regardless of the product number. In order to meet the demand for miniaturization of the pad portion.

[0009]

The first means is that a power supply wiring or a grounding wiring and a signal wiring are formed therein and a die attach portion on which an IC is mounted and a terminating resistor are provided. A power supply or ground pad connected to either the wiring or the ground wiring, a signal pad connected to the signal wiring, and a resistance pad connected to the terminating resistor are arranged in three rows around the die attach portion. A high-density IC package characterized in that:

In this first means, it is desirable that
A power supply or ground pad, a signal pad, and a resistor pad are arranged in the same plane.

A second means is a method for manufacturing a high-density IC package characterized by comprising the following steps (A).
A step of manufacturing a thick-film multilayer wiring board having at least a power supply wiring or a ground wiring and a signal wiring formed therein and having a die-attach portion for mounting an IC on the surface thereof; Forming, by a thin film method, a metal film serving as a terminating resistor connected to either the power supply wiring or the ground wiring around the touch portion; (C) a power supply connected to either the power supply wiring or the ground wiring on the metal film; Forming a grounding pad, a grounding pad, a signal pad connected to a signal wiring, and a resistance pad connected to a terminating resistor by a thin-film method; (D) forming the pads and forming a surface of the thick-film multilayer wiring board; And joining the sealing frame to the substrate.

Here, the arrangement order of the power supply or ground pad, the signal pad, and the resistor pad is not particularly limited, and in short, a large number of three rows may be arranged around the die attach portion. However, it is desirable to arrange pads of the same type in a direction parallel to the arrangement direction of the pads on the IC. For example, the arrangement is such that the front row is all power or ground pads, the middle row is all signal pads, and the last row is all resistor pads. Further, it is desirable that the signal pad and the resistor pad be adjacent to each other.

[0013]

In the first means, the power supply or grounding pad, the signal pad and the resistance pad are arranged in three rows around the die attach portion regardless of the type and arrangement of the pads on the mounted IC. Since these pads are arranged in a thick film, the same screen mask can be applied regardless of the product number of the IC package. The same photomask can be applied regardless of the package part number.

After the IC is mounted, one of the opposing pads on the package side may be selected and wire-bonded in accordance with the type and arrangement of the pads on the IC. That is, if the pad on the IC is a power supply pad, the power supply pad is selected from the three opposing pads on the package side, and if the IC pad is a signal pad, the power supply pad is selected on the package side. The signal pad is selected from the three opposing pads as the pads, and wire bonding is performed. In this case, I
If the same type of pads are arranged in a direction parallel to the arrangement direction of the pads on C, selection of wire bonding becomes easy.

If it is necessary to terminate the signal at 50Ω or the like, the signal pad and the resistor pad are wire-bonded. Therefore, as described above, it is preferable that the signal pad and the resistor pad are adjacent to each other because there is no possibility that the bonding wire crosses another bonding wire and short-circuits.

If the power supply or ground pad, the signal pad, and the resistor pad are formed on the same plane, the pad may be formed of a thin film or a thick film. Since one photomask or screen mask is sufficient, the pad forming step can be shortened.

In the second means, since the terminating resistor and various pads are formed by a thin film method, fine wiring of the pad portion can be achieved. In addition, since the terminating resistor and various pads are formed by a thin film method before joining the sealing frame, a step on the substrate surface due to the presence of the sealing frame does not occur. Therefore, when the terminating resistor and various pads are formed by the thin film method, first, the coating thickness of the photosensitive emulsion becomes uniform. Also,
Since there is no step, when exposing the coated photosensitive emulsion through a photomask, there is no gap between the photomask and the exposed surface of the photosensitive emulsion, and errors in the exposure area due to light diffraction etc. can be eliminated. it can.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-density IC package according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the high density I
FIG. 2 is an enlarged view of a portion A of FIG. 1 and FIG. 3 is a longitudinal sectional view of a main part of the high-density IC package.

As shown in FIG. 3, a high-density IC package 1 includes a thick-film multilayer wiring board 2 and a thick-film multilayer wiring board 2.
Thin-film wiring layer 3 formed on the main surface of the device, and a sealing frame 4 made of Kovar or the like joined to the peripheral edge of the upper surface thereof
And I / O pins 5 made of a number of Kovar or the like joined to the back surface of the thick-film multilayer wiring board 2.

The thick-film multilayer wiring board 2 includes a plurality of insulating layers made of ceramics mainly composed of alumina or the like, various wiring patterns (not shown) formed on the main surface of the insulating layers,
Blaze pads (not shown) formed for brazing the I / O pins 5 to the back surface of the lowermost insulating layer, and an insulating film 25 formed to cover the blaze pads to insulate between the blaze pads. It has.

In the present embodiment, the combination of the insulating layer and the wiring pattern of the thick-film multilayer wiring board 2 is such that the lowermost insulating layer 21 for joining the I / O pins and the ground formed on the back surface except for the blaze pad are formed. A wiring pattern, a signal wiring pattern formed on the insulating layer 21, and a second insulating layer 2.
2, a ground wiring pattern formed thereon, and a third
Has a four-layer structure of an insulating layer 23, a signal wiring pattern formed thereon, and a fourth insulating layer 24. Each of the insulating layers is provided with a conductive via (not shown) as appropriate in order to achieve conduction between the layers.

The thin film wiring layer 3 includes a resistor pattern 31 (metal film) formed on the surface of the fourth insulating layer of the thick film multilayer wiring board 2 and various electrode patterns formed on the resistor pattern 31. 32 (metal film). The material of the resistor pattern 31 is tantalum nitride Ta ₂ N, and the material of the electrode pattern 32 is palladium Pd, which is plated with gold.

As shown in FIG. 2, the electrode pattern 32 includes a plurality of power supply or ground pads 32a... 32a arranged on the inner peripheral side closest to the die attach portion 26.
And a number of signal pads 32b arranged outside thereof.
32b and a number of resistance pads 32c arranged further outside
.. 32c and a power supply wiring 32d surrounding the pad group arranged in three rows and columns with an insulating interval therebetween. The resistor pattern 31 exists below the pad group and the power supply wiring, and is provided with resistance pads 32c... 32c.
The exposed portion between the power supply wiring 32d and the power supply wiring 32d becomes 50Ω termination resistors 31a... 31a. Electrode pattern 32
Of the metallized portion 32 for joining the sealing frame 4
e. Next, a method of manufacturing a high-density IC package according to this embodiment will be described.

First, tungsten W is coated on the surface of four green sheets mainly composed of ceramics such as alumina.
Alternatively, a metal paste such as molybdenum Mo is screen-printed in a predetermined pattern to form various wiring patterns and a blaze pad. A conductive via for interconnecting each wiring and the like of the printed green sheet is punched out, and this via is also filled with a metal paste. An alumina paste is applied to the other surface of the lower surface of the lowermost green sheet except for the portion serving as the blaze pad. And after these green sheets are laminated and thermocompression bonded, 1500
It is baked at a high temperature of about ° C. to form a thick-film multilayer wiring board 2.
The top surface of the thick film multilayer wiring board 2 is polished, and the I / O pins are Ni-plated after brazing the I / O pins to the blaze pad.

Next, tantalum nitride is sputtered on the polished top surface of the thick-film multilayer wiring board 2 and palladium is further sputtered. Then, a photosensitive emulsion is applied to the sputtered portion and exposed through a photomask having a predetermined pattern. Then, electrode pattern 3
2, each pad 32a, 32b, 32c, 32d, 3
The photosensitive emulsion corresponding to 2e is removed by development. Then, gold plating is applied to the portion from which the photosensitive emulsion has been removed. Subsequently, the remaining photosensitive emulsion is removed, and unnecessary portions of palladium are removed with an etchant. Again, the photosensitive emulsion was applied, the pattern of the resistor 31a was exposed, the photosensitive emulsion in a portion where the pattern was not formed was removed with a developing solution, and the tantalum nitride film in that portion was removed with an etching solution. Subsequently, the remaining photosensitive emulsion is removed to form the thin film wiring layer 3.

Finally, a sealing frame 4 made of ceramics, Kovar, or the like is bonded to the metallized portion 32e at the peripheral edge of the thin film wiring layer 3 using a gold-tin eutectic brazing material. As a result, a high-density IC package is completed.

After the IC is mounted on the die attach unit, the power supply or ground pad 32a and the signal pad 32a are selected from the pads on the IC and the pad group arranged in three rows corresponding to each of the pads. In the case of a wiring that needs to be wire-bonded to one of the signal pads 32b and to terminate a signal at 50Ω or the like, the signal pad 32b and the resistor pad 32c are further wire-bonded.

In this embodiment, pads of the same type are arranged in a direction parallel to the arrangement direction of the pads on the IC.
That is, the innermost pads are all power supply or ground pads 32a, the intermediate pads are all signal pads 32b, and the outermost pads are all resistance pads 32c. Therefore, selection of wire bonding is easy. Also, the signal pad 32b
And the resistor pad 32c are adjacent to each other, so that there is no possibility that the bonding wire intersects with another bonding wire to cause a short circuit.

[0029]

According to the present invention, the same screen mask or the same photomask can be applied irrespective of the product number of the IC package. Therefore, the pad forming process and the device for the same can be unified, and the production cost can be reduced. Also, since the terminating resistor and various pads are formed by a thin film method,
Fine wiring of the pad portion can be achieved.

[Brief description of the drawings]

FIG. 1 is a plan view of a high-density IC package according to an embodiment.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a longitudinal sectional view of a main part of the high-density IC package of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 High-density IC package 2 Thick film multilayer wiring board 31a Terminating resistor 32a Power supply or ground pad 32b Signal pad 32c Resistance pad 4 Sealing frame

Continuing on the front page (72) Inventor Toru Kishimoto Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo (72) Inventor Shinichi Sasaki 1-1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Stock In-company (56) References JP-A-63-187651 (JP, A) JP-A-1-214405 (JP, A) JP-A-2-1148 (JP, A) JP-A-63-147355 (JP, A) Japanese Patent Application Laid-Open No. 1-119047 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/12 H01L 21/60

Claims (3)

(57) [Claims] A power supply having at least a power supply wiring or a grounding wiring and a signal wiring formed therein and having a die attach portion on which an IC is mounted and a terminating resistor. Alternatively, a high-density IC package, wherein ground pads, signal pads connected to signal wirings, and resistance pads connected to terminating resistors are arranged in three rows around the die attach portion. 2. The high-density IC package according to claim 1, wherein the power supply or ground pad, the signal pad, and the resistor pad are arranged on the same plane. 3. A method for manufacturing a high-density IC package, comprising the following steps: (A) A step of manufacturing a thick-film multilayer wiring board in which at least a power supply wiring or a ground wiring and a signal wiring are formed and which has a die attach portion on the surface of which an IC is mounted. (B) A step of forming a metal film serving as a terminal resistor connected to either the power supply wiring or the ground wiring by a thin film method around the die attach portion on the surface of the thick film multilayer wiring board. (C) A power supply or ground pad connected to either the power supply wiring or the ground wiring, a signal pad connected to the signal wiring, and a resistance pad connected to the terminating resistor are formed on the metal film by a thin film method. Process. (D) a step of joining a sealing frame to the surface of the thick-film multilayer wiring board after forming the pads.