JP2751679B2 - Adjustment method of resonance frequency of resonance circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a resonance frequency of a resonance circuit.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram of a main part of a voltage controlled oscillation circuit, and FIG. 4 is a mounting configuration diagram around a resonance circuit in the voltage controlled oscillation circuit of FIG.

The voltage-controlled oscillation circuit is configured to inject the output of the resonance circuit 2 into the base of the oscillation transistor TR via a coupling capacitor C3, as shown in FIG. The resonance circuit 2 has a variable capacitance diode D1, first and second fixed capacitance elements C1 and C2, and an inductance element L1 as resonance capacitances, and sets the variable capacitance diode D1 and the first fixed capacitance element C1 in series. These are connected in parallel with the inductance element L1, and a second fixed capacitor C2 is connected in parallel with the inductance element L1.

The periphery of such a resonance circuit 2 is mounted on a circuit board 4 as shown in FIG. In FIG. 4, only the inductance element L1 is illustrated in a physical form. Excluding the inductance element, the variable capacitance diode D1, both fixed capacitances C1 and C2, the coupling capacitance C3, and the oscillation transistor TR are described. For convenience of explanation, it is indicated by a circuit symbol.

In FIG. 4, one main surface side of the circuit board 4 is partially shown as a plane, and on the one main surface, an inductance element L1 is provided with an inverted U-shaped quarter-wave ground type strip line electrode, that is, A ground electrode is formed on the entire main surface other than the main surface, which is not shown in the drawing. One end of the resonance inductance electrode 6 is connected to a ground electrode via a through hole (not shown) formed in the circuit board 4. The connection of one end of the resonance inductance electrode 6 to the ground electrode is indicated by the earth circuit symbol, and the connection of the other elements to the earth electrode is also indicated by the earth circuit symbol. The first fixed capacitance C1 has one end connected to the other end of the resonance inductance electrode 6 and the other end connected to the cathode of the variable capacitance diode D1. The second fixed capacitance C2 is connected between both ends of the resonance inductance electrode 6. In this case, the second fixed capacitance C2 may include a discrete capacitance element and a stray capacitance component between the resonance inductance electrode and the ground electrode. One end of the coupling capacitor C3 is connected to the other end of the resonance inductance electrode 6, and the other end is connected to the base of the oscillation transistor TR.

In the resonance circuit 2 mounted on the circuit board 4 as described above, the resonance frequency may be adjusted by selecting and combining the elements constituting the resonance circuit. Is well-known by performing a function trimming of a part thereof. In addition,
The reason why the resonance frequency can be adjusted by this function trimming is well known and will not be described in detail, but the point is that the trimming length of a part of the resonance inductance electrode 6 as shown in the drawing, the trimming interval, etc. By adjusting the number of trimmings as appropriate, the substantial length of the resonance inductance electrode 6 is adjusted and its inductance value changes, and as a result, the resonance frequency is adjusted.

[0007] Typical examples of the functional trimming include an electrode shaving method using a luter and a thermal melting method using a laser beam.

[0008]

In the former function trimming using a luter, since a metal is in direct contact with the resonance inductance electrode 6, the resonance frequency differs between a state where the metal is not in contact and a state where it is not. Because it comes
The need for a difficult trimming operation that takes that into account arises,
It takes a long time to adjust the resonance frequency.

In the latter function trimming using a laser beam, the circuit board 4 is generally made of resin, but the circuit board 4 is not trimmed when the resonance inductance electrode 6 is trimmed, although the former does not have the same problem as the former. The laser beam is carbonized and deteriorated by the heat of the laser beam, and as a result, the characteristics of, for example, a voltage-controlled oscillation circuit using the resonance circuit 2 are greatly affected.

[0010] Accordingly, it is an object of the present invention to enable the function trimming of the resonant inductance electrode so that the circuit board is not carbonized by the heat of the laser beam in the function trimming by the laser beam.

[0011]

In order to achieve the above object, a method for adjusting a resonance frequency of a resonance circuit according to a first aspect of the present invention includes a method of adjusting a resonance inductance electrode formed on a circuit board. , a portion of the electrode, the times
Together constitute at which a metal film is formed at least the upper surface of the heat-resistant base member made of a different material from the road substrate, the metal film is characterized in that to adjust the resonance frequency of the resonance circuit by functional trimming laser beam I have.

According to a second aspect of the present invention, there is provided a method of adjusting a resonance frequency of a resonance circuit, wherein a part of the electrode is formed of a chip component.

[0013]

According to the first aspect, when a part of the resonance inductance electrode is functionally trimmed with a laser beam, the part of the electrode is made of a material different from the circuit board.
Since by forming a metal film on the upper surface of the heat-resistant base member made of, laser radiation heat is received by the heat-resistant base body when going to adjust the resonant frequency of the metal film functioning trimming,
The circuit board is not carbonized by the heat.

According to the second aspect, since a part of the electrode is a chip part, when the function trimming fails, it is necessary to replace the circuit board itself including the resonance inductance electrode only by replacing the chip part. Absent.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view of a principal part in which the periphery of a resonance circuit in a voltage-controlled oscillation circuit is mounted on a circuit board, and FIG.
FIG. 3 is a cross-sectional view taken along line AA of FIG. This voltage-controlled oscillation circuit is the same as that shown in FIG. 3, and FIG. 1 shows the resonance inductance electrode 6 formed on the circuit board 4 around the resonance circuit 2 in the voltage-controlled oscillation circuit. The chip part 8 of the main part of the invention is shown in a plan view, and the illustration (including the circuit symbol) of the parts of the voltage controlled oscillation circuit including the parts around the other resonance circuit 2 is omitted. FIG.
In FIG. 2 and FIG. 2, parts corresponding to those in FIG. 3 according to the conventional example are denoted by the same reference numerals, and detailed description of the parts corresponding to the same reference numerals is omitted.

1 and 2, reference numeral 4 denotes a circuit board;
6 is a resonance inductance electrode, 8 is a chip component, and 10 is a ground electrode.

In these figures, a part of the resonance inductance electrode 6 is cut off, and a chip component 8 is soldered to a position opposed to the cut ends 6a, 6a. The chip component 8, ceramic, for example, materials such as say alumina, that is, the circuit board 4
A metal film 8b is formed on an upper surface of a heat-resistant base 8a made of a different material.
Are formed into a chip state.

In adjusting the resonance frequency, the metal film 8b of the chip component 8 is functionally trimmed with a laser beam into a comb state as shown. Reference numeral 12 denotes a state where the function trimming is performed by the laser beam. Although the form of this function trimming is comb-shaped in this example, the present invention is not limited to this form. For example, when the number of comb-shaped function trimmings is increased, the substantial length of the resonance inductance electrode 6 is increased, thereby increasing the resonance inductance value and decreasing the resonance frequency. By setting the length and the number of the comb-shaped functional trimming length appropriately, the resonance frequency can be adjusted to a desired value. Since such function trimming itself is well known, a detailed description thereof will be omitted.

As described above, according to the present invention, since the circuit board 4 is not directly irradiated with the laser beam when performing the functional trimming with the laser beam, the circuit board 4 is not carbonized by the heat of the laser beam and deteriorates. It is possible to accurately adjust the resonance frequency without adversely affecting the characteristics of the oscillator circuit. Even if the function trimming fails, the chip frequency can be easily replaced with a new one and the resonance frequency can be adjusted by the function trimming again.

[0021]

As described above, according to the present invention, when a part of a resonance inductance electrode is functionally trimmed with a laser beam, a part of the electrode is connected to the circuit board.
Different consisting on the upper surface of the heat-resistant base member was obtained by forming a metal film material, the laser beam of heat when going to adjust the resonant frequency of the metal film functioning trimmed refractory <br/> group member As a result, the circuit board is not carbonized by the heat, so that the resonance frequency can be adjusted accurately and easily. Further, when a part of the electrode is a chip component, even if the function trimming fails, the function trimming can be performed again by replacing the chip component, which is convenient.

[Brief description of the drawings]

FIG. 1 is a plan view of a circuit board for explaining a method of adjusting a resonance frequency of a resonance circuit according to one embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a circuit diagram of a main part of the voltage controlled oscillation circuit.

FIG. 4 is a plan view of a circuit board for explaining a conventional method of adjusting a resonance frequency.

[Explanation of symbols]

2 resonant circuit 4 circuit board 6 resonant inductance electrode 8 chip component 8a heat-resistant base member 8b metal film

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03J 1/00 H03J 3/20 H01P 7/00-7/10 H01P 11/00

Claims (2)

(57) [Claims] A part of the resonance inductance electrode (6) formed on a circuit board (4) is made of a material different from that of the circuit board (4) . together constitute at least the upper surface of the base body (8a) in which a metal film has been formed (8b), to adjust the resonance frequency of the resonance circuit (2) by functional trimming the metal film (8b) with laser A method for adjusting a resonance frequency of a resonance circuit. 2. The method according to claim 1, wherein a part of the electrode is constituted by a chip component.