JP3513434B2 - Circuit board - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board on which a semiconductor element is mounted, and more particularly to a circuit board having a terminating resistor formed on one end side of a signal transmission path electrically connected to the semiconductor element.

[0002]

2. Description of the Related Art In a circuit board on which a semiconductor element is mounted, a terminating resistor is formed at one end of a signal transmission line electrically connected to the semiconductor element, and a terminating resistor is formed at a connection portion between the semiconductor element and the signal transmission line. There are circuit boards designed to reduce signal reflection loss. 6 and 7 are a cross-sectional view and a plan view showing a configuration of a conventional example of a circuit board 10 in which a terminating resistor is formed on one end side of a signal transmission path. FIG. 7 shows a surface of the circuit board 10 on which a semiconductor element is mounted. Reference numeral 8 denotes a chip resistor as a terminating resistor, which is arranged around the region A where the semiconductor element 12 is mounted, as shown in FIG. Reference numeral 14 is a pad portion for flip-chip connecting the semiconductor element 12. The pad portion 14 is formed so as to correspond to the arrangement of the electrode terminals 16 of the semiconductor element 12.

Reference numeral 18 is a frame-shaped ground pattern, and 20 is a wiring pattern for electrically connecting the chip resistor 8 to the pad portion 14 and the ground pattern 18. External connection terminals 22 for mounting are arranged in an area array on the surface of the circuit board 10 opposite to the surface on which the semiconductor elements are mounted.
The external connection terminal 22 and the pad portion 14 are electrically connected to each other through the via 24 formed in the circuit board 10. Further, the ground pattern 18 is also electrically connected to the external connection terminal 22 via the via 24 and has a ground potential. The circuit board 1
For 0, either a resin substrate or a ceramic substrate can be used.

[0004]

The chip resistor 8 described above is used.
8 and 9 show electrical connection diagrams of a circuit board in which is incorporated as a terminating resistor. A chip resistor 8 is arranged as a terminating resistor R outside the region where the semiconductor element 12 is mounted, and a via 24 and a signal transmission path S formed by a wiring pattern are electrically connected to the electrode terminal 16 of the semiconductor element 12.
As shown in the figure, in the conventional circuit board 10, a region for arranging the terminating resistor such as the chip resistor 8 is secured outside the region A on which the semiconductor element 12 is mounted. Therefore, the conventional circuit board 10 must be large in size in order to secure a region in which the terminating resistor is arranged.

Further, when a chip resistor is used as the terminating resistor, the number of parts is increased, and it is necessary to mount the terminating resistor on the circuit board 10. Therefore, there is a problem that work efficiency is lowered and manufacturing cost is increased. . The present invention has been made to solve these problems, and an object thereof is to easily form a terminating resistor on a circuit board and improve manufacturing efficiency.
It is an object to provide a circuit board that can effectively achieve miniaturization.

[0006]

In order to achieve the above object, the present invention has the following constitution. That is, a pad portion, which is electrically connected to the semiconductor element by flip chip connection, is formed on the mounting surface on which the semiconductor element is mounted, corresponding to the arrangement of the electrode terminals formed on the peripheral portion of the semiconductor element. In the area surrounded by the pad section, a terminating resistor whose one end side is electrically connected to the pad section is
From the via formed in the center in the area surrounded by
It is characterized in that it is formed radially toward the pad portion . Further, the vias, and the mounting surface on which a semiconductor element is mounted, characterized in that it is formed by connecting the external connection terminal electrically formed on the opposite side. Also,
It is characterized in that the terminating resistor is formed into a film having a predetermined pattern by a screen printing method, a sputtering method or the like .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of an embodiment of a circuit board 10 according to the present invention, in which a semiconductor element 1 is mounted on a semiconductor element mounting surface of the circuit board 10.
The state where 2 is mounted is shown. The circuit board 10 of the present embodiment is characterized in that the terminating resistor 30 is formed in the region where the semiconductor element 12 is mounted. The semiconductor element 12 is mounted on the circuit board 10 by flip-chip connection via bumps.
The terminating resistor 30 is formed by utilizing the element mounting surface of the circuit board facing the lower surface region of the semiconductor element 12 mounted by flip chip connection.

The terminating resistor 30 can be formed into a thin film by using a film forming method such as a screen printing method or a sputtering method, whereby the terminating resistor 30 is formed in a region where the semiconductor element 12 is mounted. The semiconductor element 12 can be formed and mounted on the circuit board 10. FIG. 2 shows an example of forming the terminating resistor 30 formed in the region of the circuit board 10 where the semiconductor element 12 is mounted. Reference numeral 14 is a pad portion to which the electrode terminal 16 of the semiconductor element 12 is joined. In the semiconductor element 12 of this embodiment, the electrode terminals 16 are arranged in a line along the outer peripheral edge of the element. Therefore,
An inner region surrounded by the pad portion 14 is a region where the terminating resistor 30 is formed.

In the method of forming the terminating resistor 30 in the illustrated example, a connection pad portion 32 having a ground potential is formed substantially in the center of the region where the semiconductor element 12 is mounted, and the connection pad portion 32 and each pad portion 14 are formed. This is a method of forming the terminating resistor 30 linearly between and. The connection pad portion 32 is for being electrically connected to the base end side (the other end side) of each of the terminating resistors 30 to have a common ground potential of the terminating resistors 30. As shown in FIG. 1, the connection pad portion 32 is electrically connected to the external connection terminal 22a joined to the other surface of the circuit board 10 via the via 24 formed in the circuit board 10. The external connection terminal 22a is set to the ground potential.

In FIG. 2, the terminating resistor 30 is formed in a region of a circle C centered on the connection pad portion 32, and the conductor pattern 34 is provided between the tip portion (one end side) of the terminating resistor 30 and the pad portion 14.
To connect electrically. Terminating resistor 3 in the area of circle C
0 is formed by making the lengths of all the terminating resistors 30 formed between the connection pad portion 32 and the pad portion 14 constant (the same length as the radius of the circle C) and making each resistance value constant. Has the meaning to

The terminating resistor 30 can be formed to have a desired resistance value by screen-printing a paste containing a resistance material such as tantalum nitride to a predetermined thickness to form a predetermined length and width. it can. The resistance value of the terminating resistor 30 depends on the material used and the length, width, and thickness of the terminating resistor 30. Therefore, if all the terminating resistors 30 are formed to have the same length as in the present embodiment, the resistance values of the terminating resistors 30 can be made uniform by making the widths and thicknesses the same. It is also possible to make the terminating resistor 30 into a curved shape or change the line width individually. It is also possible to change the length of the terminating resistor 30 or change the line width so as to obtain a desired resistance value. Further, the common connection pad portion 32 is not formed, but the connection pad portion 32 is formed for each terminating resistor 30, and each connection pad portion 3 is formed.
It is also possible to set 2 to the ground potential.

In the present embodiment, as a method of forming the terminating resistor 30 in the region of the circuit board 10 on which the semiconductor element 12 is mounted, the maximum circle C that can be taken in the region on which the semiconductor element 12 is mounted is set to terminate the termination. When the length of the resistor 30 is made uniform, the length of the terminating resistor 30 can be made as long as possible in the mounting region of the semiconductor element 12. The present invention is characterized in that the terminating resistor 30 is formed in the region where the semiconductor element 12 is mounted. Therefore, since the region where the terminating resistor 30 is formed is limited to a narrow range, as a method for ensuring the length of the terminating resistor 30 as long as possible under such a condition, the maximum direction of the circle C in the radial direction of the circle C can be considered. It is effective to form the terminating resistors 30 in each of the terminating resistors 30.
Is also an effective means in that they can be formed to have the same resistance value.

The circuit board 10 shown in FIG.
The outer dimensions of the substrate are formed larger than the outer dimensions of the wiring pattern 36, and the wiring pattern 36 whose one end side is connected to the electrode terminal 16 is arranged outside the region where the semiconductor element 12 is mounted. The other end of the wiring pattern 36 is electrically connected to the external connection terminal 22 formed on the other surface of the circuit board 10 via the via 24.

3 and 4 are electrical connection diagrams of the circuit board 10 incorporating the terminating resistor 30. FIG. 3 shows a planar arrangement of the terminating resistors 30 on the surface of the circuit board 10 on which the semiconductor elements are mounted. FIG. 4 shows that the signal transmission path composed of the via 24 and the wiring pattern 36 is electrically connected to the electrode terminal 16 and is terminated by the termination resistor 30. The base end of the terminating resistor 30 is at ground potential, and by matching the resistance value of the terminating resistor 30 with the impedance of the signal transmission line, the reflection loss of the signal at the connecting portion between the signal transmission line and the semiconductor element 12 is reduced. Can be reduced. The wiring pattern 36 forms a part of the signal transmission path.

As described above, in the circuit board 10 according to the present invention, the terminating resistor 30 is formed in the area on the circuit board 10 where the semiconductor element 12 is mounted.
It is also possible to make the size of the same as that of the semiconductor element 12. FIG. 5 shows an example of a semiconductor device in which the semiconductor element 12 is mounted on the circuit board 10 having the same size (mounting area) as the semiconductor element 12. The semiconductor element 12 is mounted on the circuit board 10 by flip-chip connection, and the terminating resistor 30 is formed in the region where the semiconductor element 12 is mounted, as in the above embodiment. Similar to the configuration of FIG. 1, a connection pad portion 32 to which the base ends of the terminating resistors 30 are commonly connected is formed, and the terminating resistors 30 radially extending in the direction of the pad portion 14 are formed around the connection pad portion 32. ing.

The connection pad portion 32 is electrically connected to the external connection terminal 22a on the mounting surface side of the circuit board 10 via the via 24. The pad portion 14 to which the electrode terminal 16 is joined is also electrically connected to the external connection terminal 22 formed on the mounting surface of the circuit board 10 via the via 24.
The external connection terminal 22a is set to the ground potential, and the external connection terminal 22 is connected to the signal transmission path. On the mounting surface of the circuit board 10, the external connection terminals 22, 2
A wiring pattern for arranging 2a arranged in an area array is formed.

After mounting the semiconductor element 12 on the circuit board 10, the gap between the semiconductor element 12 and the circuit board 10 may be filled with an underfill material 40 to seal the connection portion. The underfill material 40 protects the connection,
The semiconductor element 12 and the circuit board 10 are integrally bonded.
The mounting area of the circuit board 10 is the same as the mounting area of the semiconductor element 12, and the terminating resistor is the semiconductor element 1 of the circuit board 10.
The semiconductor device formed in the region where 2 is mounted can be used for various purposes as a product having excellent high frequency characteristics and as a small and compact semiconductor device.

In each of the above-described embodiments, the terminal resistor 30 is formed on all the electrode terminals 16, but
Not all the electrode terminals 16 are connected to the signal transmission path through which the high frequency signal is transmitted. This is because the power supply line, the ground line, and the like are also connected to the electrode terminal 16. Therefore, when forming the terminating resistors 30, it is not necessary to connect the terminating resistors 30 to all the electrode terminals 16, and it is sufficient to connect the terminating resistors 30 only to the pad portions 14 where the terminating resistors need to be connected.

In the embodiment shown in FIG. 1, the circuit board 1
Although the mounting surface of 0 is the surface opposite to the surface on which the semiconductor element 12 is mounted, the mounting surface may be on the same side as the surface on which the semiconductor element 12 is mounted. In that case, the circuit board 10
A cavity for accommodating the semiconductor element 12 is provided in the cavity, and the semiconductor element 12 is accommodated in the cavity to be mounted as a cavity-down type semiconductor device.

The circuit board according to the present invention has a terminating resistor 3 formed by a film forming method such as a screen printing method or a sputtering method.
Since 0 is formed, there is an advantage that the terminating resistor 30 can be easily formed. According to the film forming method, the terminating resistors 30 can be collectively formed, so that it is not necessary to use resistance components such as chip resistors, and the work can be performed efficiently. In the case of forming the circuit board 10, the terminating resistor 30 can be formed by using the circuit board 10 formed in pieces as a work, or after the terminating resistance 30 is patterned on a large-sized work, it is cut into pieces to form a circuit. The substrate 10 can also be obtained. The method of collectively forming the terminating resistors 30 in this way is far more efficient than the method of handling multiple components such as chip resistors.

Further, in the method of forming the terminating resistor 30 by a film forming method such as a screen printing method, the terminating resistor 30 can be formed in an arbitrary pattern, and it is easy to form a fine pattern. From the semiconductor element 12
The terminating resistor 30 is provided in a limited area such as a mounting area of
There is also an advantage that can be formed. Further, there is an advantage that it is possible to easily match the required resistance value by selecting the resistance material used for the terminating resistor 30 and appropriately designing the pattern to be formed.

[0022]

As described above, in the circuit board according to the present invention, the terminating resistance is formed in the area of the circuit board where the semiconductor element is mounted, and the terminating resistance is surrounded by the pad portion.
From the via formed in the central part of the inside toward the pad part
Radial formation allows termination resistance in a narrow area.
It becomes possible to secure the length of. Further, by forming the film-shaped terminating resistor by screen printing or the like, it becomes possible to collectively form the terminating resistor, and since the parts such as the chip resistor are not used, the manufacturing work efficiency can be improved. Therefore, the manufacturing cost can be effectively reduced. Further, since the terminating resistance can be formed in an arbitrary pattern , it is possible to form the terminating resistance according to the product, and it is possible to apply the terminating resistance to products for various purposes.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which a semiconductor element is mounted on a circuit board according to the present invention.

FIG. 2 is an explanatory diagram showing a planar arrangement of terminating resistors formed on a circuit board.

FIG. 3 is an explanatory diagram showing an arrangement of terminating resistors formed on a circuit board.

FIG. 4 is an explanatory diagram showing electrical connection between a semiconductor element and a terminating resistor.

FIG. 5 is a cross-sectional view showing a state in which a semiconductor element is mounted on a circuit board formed in the same size as the semiconductor element.

FIG. 6 is a cross-sectional view of a conventional circuit board in which a chip resistor is formed as a terminating resistor.

FIG. 7 is a plan view of a conventional circuit board on which a chip resistor is formed.

FIG. 8 is an explanatory diagram showing electrical connection between a semiconductor element and a terminating resistor in a conventional circuit board.

FIG. 9 is an explanatory diagram showing an arrangement of terminating resistors in a conventional circuit board.

[Explanation of symbols]

10 circuit board 12 Semiconductor element 14 Pad part 16 electrode terminals 20 wiring patterns 22, 22a External connection terminal 24 vias 30 termination resistance 32 Connection pad section 34 conductor pattern 36 wiring pattern 40 Underfill material

Claims (3)

(57) [Claims] 1. A pad portion electrically connected to a semiconductor element by flip-chip connection is formed on a mounting surface on which a semiconductor element is mounted, corresponding to an arrangement of electrode terminals formed on a peripheral portion of the semiconductor element. A terminating resistor whose one end side is electrically connected to the pad section is provided in the area surrounded by the pad section by the pad section.
From the via formed at the center in the area surrounded by
A circuit board, which is radially formed toward the pad portion . Wherein said vias claim 1, characterized in that it is formed by connecting the external connection terminal electrically formed on the surface opposite to the mounting surface on which a semiconductor element is mounted The described circuit board. 3. The circuit board according to claim 1, wherein the terminating resistor is formed in a film having a predetermined pattern by a screen printing method, a sputtering method, or the like.