JP2013187300A - High-frequency circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency circuit device which enables good wire bonding and which can obtain good high-frequency characteristics across a wide frequency band.SOLUTION: A high-frequency circuit device of an embodiment comprises: a main line provided on a surface of a dielectric substrate; a ground pad which is provide at a distance from the main line and grounded; an electrode pad which is provided in a place extending from the end of the mainline and at a distance from the main line and connected by the main line and a wire.

Description

  Embodiments described herein relate generally to a high-frequency circuit device having a bonding wire.

  For example, MMIC (Monolithic Microwave IC) is often used to make a high-frequency semiconductor chip of a portable terminal device small and light. Such an MMIC is installed and fixed on the main board / package and assembled.

  In the MMIC, in order to obtain good RF characteristics with a high-frequency probe during inspection, the impedance is set to 50Ω, and therefore the width of the main line is often narrowed. For example, assume that a GaAs substrate of an MMIC chip is used. In order to make the thickness of the substrate 100 μm and the characteristic impedance 50Ω, the width of the main line is about 70 μm. If the width of the RF pad connected to one end of the main line is set to this level, wire bonding with sufficiently good characteristics cannot be performed.

  For this reason, it is necessary to increase the width of the RF pad. However, in a particularly high frequency region, the parasitic capacitance increases at the portion where the RF pad and the main line are connected, and the RF characteristics are deteriorated.

  Therefore, as shown in FIG. 5, a pad sub-portion 42 is provided on both sides of the RF pad (pad main portion) 41 with a predetermined interval, and the wire is bonded across the wiring outside the chip, the pad main portion, and the pad sub-portion. The structure to do was considered. In FIG. 5, a main line 44 is provided on the upper surface of a GaAs substrate 43 provided with a ground metal film on the back surface, and an RF pad 41 is provided at an end thereof. Ground pads 45 are provided on both sides of the RF pad 41 and are grounded by via holes 46. Pad sub-portions 42 are provided on both sides of the RF pad (pad main portion) 41 via slits with a predetermined interval.

JP 2011-233906 A

  The conventional high-frequency circuit device having the structure shown in FIG. 5 can be designed to minimize the influence at a specific frequency, but it is difficult to reduce the influence over a wide frequency band.

  The present invention provides a high-frequency circuit device capable of performing good wire bonding and obtaining good high-frequency characteristics over a wide frequency band.

  In order to solve the above-described problem, an embodiment of the present invention includes a main line provided on a surface of a dielectric substrate, a ground pad provided apart from the main line and grounded, and the main line. Provided is a high-frequency circuit device having an electrode pad provided on an extension of an end portion and spaced apart from the main line and connected to the main line by a wire.

It is a figure which shows the structure of the high frequency circuit apparatus (semiconductor circuit chip) of one Embodiment. It is a figure which shows the state which earth | grounded the high frequency circuit apparatus of one Embodiment to the main board | substrate. It is a figure which shows the relationship between the use wavelength and gap width of the high frequency circuit apparatus shown in FIG. It is a figure which shows the structure of the high frequency circuit apparatus of other embodiment. It is a figure which shows the structural example of the conventional high frequency circuit apparatus.

  An embodiment will be described below with reference to the drawings. A semiconductor circuit chip 10 which is a high-frequency circuit device of one embodiment is shown in FIG.

  For example, a main line 12 having a line width of about 70 μm is provided on the surface of a dielectric substrate 11 having a ground conductor on the back surface, for example, a GaAs substrate, for example, by metal deposition. The width of the main line 12 is assumed to be w1. A microstrip line is constituted by the ground conductor, the dielectric substrate 11 and the main line 12 provided on the back surface.

  Although not shown, a passive element such as a resistor and an active element such as a transistor are connected to the main line 12 as a circuit element.

  Ground pads 13a and 13b are provided on both sides in the direction perpendicular to the length direction (x direction) of the main line 12, and these ground pads 13a and 13b are connected to ground conductors on the back surface by via holes 14a and 14b, respectively. Has been.

  Then, on the extension of the end of the main line 12 (x direction), for example, a rectangular electrode pad 15 is provided at a predetermined distance Wg. The width of the electrode pad 15 in the x direction is Wx, and the width in the vertical direction (y direction) is Wy. The main line 12 and the electrode pad 15 are connected by one or a plurality of wires 17.

  FIG. 2 shows a state in which the semiconductor circuit chip 10 is mounted and fixed on the main substrate 21. The electrode pad 15 is connected to the connection pad 23 on the main substrate 21 by, for example, three wires 22a, 22b, and 22c.

  Now, assuming that the diameter of the wire is 25 μm, the width connected by this wire needs to be about 60 μm in consideration of the collapse of the wire. If three wires are connected in a row on the electrode pad 15, the width Wy in the y-axis direction is required to be about 180 μm. Similarly, if two wires are connected on the electrode pad 15 in the x direction, the width Wx in the x-axis direction is about 120 μm or more. Therefore, if the electrode pad 15 has a shape of 120 × 180 μm or more, it is possible to connect wires in the situation shown in FIG. As described above, the maximum number of wires connected to the terminals outside the chip is limited by the width of the electrode pad described above.

  The relationship between the gap width Wg shown in FIG. 1 and the operating frequency is shown in FIG. In FIG. 3, the horizontal axis represents the operating frequency f (MHz), and the vertical axis represents the gap width Wg (mm) between the end of the main line 12 and the electrode pad 15.

  A solid line 31 indicates 1/20 of the operating wavelength λ, and a dotted line 32 indicates a value of 1/3 of the thickness T of the dielectric substrate 11. Usually, it is about 1/20 or less of the wavelength λ, and preferably 1/3 or more of the dielectric substrate, so that the gap width Wg is surrounded by a solid line and a dotted line between the respective operating frequencies. Then it is preferable.

  For example, when the operating frequency is 1000 MHz, the semiconductor circuit chip can be used as long as the gap width Wg is about 0.4 mm to about 30 mm and the main line 12 and the electrode pad 15 are separated. Further, when the operating frequency is 10,000 MHz, this chip can be used in the range where the gap width Wg is about 0.1 mm to about 2 mm.

  By the way, although the case where the rectangular thing was used as an electrode pad was described in the said embodiment, the shape of this electrode pad is not restricted to a square, For example, a trapezoid shape may be sufficient as shown in FIG. In this embodiment, the electrode pad 35 has a trapezoidal shape with the short side of the trapezoid facing the main line 32. Reference numerals 31 to 34b are the same as the reference numerals 11 to 14b in the embodiment shown in FIG.

  That is, a main line 32 having a line width of about 70 μm is provided on the surface of a dielectric substrate 31 having a ground conductor on the back surface, for example, a GaAs substrate, for example, by metal deposition. The width of the main line 32 is set to w1. The ground strip, the dielectric substrate 31 and the main line 32 provided on the back surface constitute a microstrip line.

  On the extension of the end of the main line 32, for example, a trapezoidal electrode pad 35 is provided at a predetermined distance (gap width). The main line 32 and the electrode pad 35 are connected by one or a plurality of wires 37.

  The electrode pad 35 having such a shape is preferable when, for example, as shown in FIG. 2, there are few wires connected to the electrode pad 35 and the main line and many wires are connected to the external main substrate. This is because these wires connected to the electrode pads are preferably as short as possible in order to suppress characteristic deterioration due to an increase in capacitance due to an increase in pad width. However, if the electrode pads have such a trapezoidal shape, the wires This is because it can be shortened.

  Of course, the shape of the electrode pad is not limited to the square shape shown in FIG. 1 and the trapezoidal shape shown in FIG. 4, and may be any shape.

  In the above-described embodiment, the example in which the ground pads are provided on both sides of the main line has been described. However, the present invention can also be applied to those having ground pads only on one side. Moreover, although the said embodiment demonstrated the aspect by which a ground pad was connected and installed in the ground conductor provided in the back surface of the dielectric substrate, the ground pad may be earth | grounded by the other method.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Semiconductor circuit chip 11 ... Dielectric substrate 12 ... Main line 13a, 13b ... Ground pad 14a, 14b ... Via hole 15 ... Electrode pad 17, 22a, 22b, 22c ... Wire 21 ... Main board 23 ... Connection pad

Claims (6)

A main line provided on the surface of the dielectric substrate;
A ground pad that is provided apart from the main line and grounded;
On the extension of the end of the main line, an electrode pad provided apart from the main line and connected to the main line by a wire;
A high frequency circuit device comprising:   The high-frequency circuit device according to claim 1, wherein the electrode pad has a rectangular shape.   The high-frequency circuit device according to claim 1, wherein the electrode pad has a trapezoidal shape. A dielectric substrate provided with a ground conductor on the back surface;
A main line provided on the surface of the dielectric substrate and connected to a circuit element;
A ground pad that is provided on both sides of the main line and is separated from the main line and connected to the ground conductor;
An electrode pad provided on the extension of the end of the main line at a predetermined distance from the main line and connected to the main line by a wire;
A high-frequency circuit device.   The high-frequency circuit device according to claim 4, wherein the electrode pad has a rectangular shape.   The high-frequency circuit device according to claim 4, wherein the electrode pad has a trapezoidal shape with a short side toward the main line.

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