JP3347981B2 - Voltage controlled oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage controlled oscillator having a resonance line disposed inside a multilayer circuit board,
The present invention relates to a voltage controlled oscillator whose resonance frequency can be adjusted by trimming.

[0002]

2. Description of the Related Art As a VCO module, a wiring conductor layer on which electronic components are mounted is provided on an upper surface, and a resonance conductor layer in which a microstrip line (hereinafter, referred to as MSL) as a resonance line is provided. It is known that a ground conductor layer is provided on a lower layer or a lower surface of a resonance conductor layer to constitute a multilayer circuit board. When the oscillation frequency of the VCO module thus configured is adjusted to a predetermined frequency, In the manufacturing process, the MSL is trimmed. FIG. 5 is an explanatory view of the conventional voltage controlled oscillator viewed from the upper surface, FIG. 6 is an explanatory view showing a state of trimming by a drill in the conventional voltage controlled oscillator, and FIG. 7 is a burr generated by trimming in the conventional voltage controlled oscillator. It is explanatory drawing which shows the state.

[0003] In these figures, reference numeral 60 denotes a multilayer substrate.
The multilayer substrate 60 has a base material made of a dielectric layer, mounts the circuit component 61 on a circuit wiring portion formed on the upper surface thereof, and has an MSL adjusting portion on the upper surface connected to the internal MSL, It has a ground layer, an MSL, and a lower ground layer. As a method of adjusting the oscillation frequency of such a voltage controlled oscillator, a part of the MSL provided inside the multilayer substrate 60 is led out to the upper surface of the multilayer substrate 60 as an MSL adjusting unit, and this MSL adjusting unit is drilled. There is known a method of performing trimming by an appropriate means such as cutting by a method such as cutting.

[0004]

In the above prior art, frequency adjustment is performed by drilling the MSL adjustment section on the upper surface with a drill, and an electronic device such as a portable radio using this kind of voltage controlled oscillator is used. In response to a strong demand for miniaturization, voltage-controlled oscillators have also been miniaturized. However, since the MSL adjustment section on the upper surface of the multilayer substrate requires space, it has been an obstacle to miniaturization.
In addition, a cover of an electromagnetic shield for preventing the influence of electromagnetic waves on peripheral components when the voltage-controlled oscillator is attached to the electronic device is attached to the front side to cover the circuit components 61 mounted on the upper surface. For this reason, the MSL adjustment unit is also covered by the cover. Therefore, when performing the frequency adjustment, the MSL adjustment unit is drilled and adjusted to a predetermined frequency before the cover is attached. At this time, the frequency adjusted by attaching the cover after the adjustment changes, so the frequency adjustment was performed in anticipation of the amount of change, but the amount of change varies due to a cover mounting error or the like. There was a limit in controlling the defect rate. Therefore, as shown in FIGS. 6 and 7, when trimming is performed using a drill 62 from the lower surface side, burrs 65 are generated not only on the lower ground layer 63 but also on the solder resist layer 64. As a result, the flatness of the lower surface is reduced, and when the lower surface of the voltage controlled oscillator is mounted on the mother board, it floats from the mother board and a soldering failure occurs.

[0005] challenge of the present invention, Nakuse the MSL adjuster which is provided in a conventional top surface can be downsized and, also, so as to perform the frequency adjustment after attaching the cover, the frequency change due to attachment of the cover a can significantly improve the failure rate Nakuse, further, to the drill cutting in the frequency adjustment
To reduce the effect of burrs on the bottom ground layer,
Maintains flatness and can be mounted in close contact with the motherboard and soldered
Give to provide a voltage controlled oscillator that prevent the failure.

[0006]

[0007]

SUMMARY OF THE INVENTION The above challenges is a substrate having a microstrip line internally made with a dielectric layer, and a wiring conductor layer mounted with electronic components mounted on the top surface of the substrate, wherein A ground conductor layer provided on the lower surface of the base material ;
The ground conductor formed by nickel plating on the ground conductor layer
An anti-burr layer having a higher hardness than the layer, a cutting groove provided by cutting and reaching the microstrip line from the grounding conductor layer, and a solder resist formed on the grounding conductor layer excluding at least the periphery of the cutting groove. It is solved from <br/> in that a layer.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing an entire embodiment of a voltage controlled oscillator according to the present invention upside down, FIG. 2 is an explanatory view of the embodiment viewed from below, FIG.
FIG. 4 is an enlarged sectional view taken along line BB of FIG. 2, and FIG. 4 is an explanatory view showing a manufacturing process of an embodiment according to the voltage controlled oscillator of the present invention.

In these figures, reference numeral 1 denotes a voltage controlled oscillator (VCO). The voltage controlled oscillator 1 has a substrate 2 made of a dielectric layer, and wiring for mounting an electronic component 13 on the upper surface of the substrate 2. A conductor layer 3, a first ground conductor layer 4 made of copper on the lower surface of the substrate 2, and a second ground conductor layer 5 inside the substrate 2.
A microstrip line (MSL) 6 disposed between the first ground conductor layer 4 and the second ground conductor layer 5;
A solder resist layer 11 is formed on the ground conductor layer 4 of FIG. 1, and a part of the solder resist layer 11 is removed to provide a frequency adjustment region 7. A cover 12 covers the upper surface on which the circuit component 13 is mounted.

The MSL 6 is, for example, rectangular in plan view, and has a smaller area than the first and second ground conductor layers 4 and 5. One end of the MSL 6 is connected to the first and second ground conductor layers 4 and 5 by through holes (not shown).

On the first ground conductor layer 4, a burr preventing layer 9 and a gold plating layer 10 having good solderability are formed. The burr prevention layer 9 is for preventing burr from being generated by drilling for frequency adjustment, and is made of a material having a higher hardness than the first ground conductor layer 4, for example, nickel. To suppress the occurrence of burrs. The burr prevention layer 9 may be made of a material other than nickel as long as the material has a higher hardness than the first ground conductor layer 4.

On the first ground conductor layer 4, a frequency adjustment region 7 for frequency adjustment is further provided.
In the frequency adjustment region 7, the internal MS is
An oval cutting groove 8 is formed by cutting a part of L6. This cutting groove 8 extends in the vertical direction in FIG. 2 with a length corresponding to the adjustment amount, and reaches the MSL 6. Then, in the cut groove 8, a sealing resin 14 for moisture prevention is coated with the solder resist layer 11.
It is filled so that it does not protrude.

As described above, conventionally, frequency adjustment has been performed by drilling the MSL adjustment unit on the upper surface side with a drill. Was an obstacle to
However, by adopting the configuration of the present embodiment,
It is possible to reduce the size of the voltage controlled oscillator by eliminating the conventional MSL adjustment unit. Further, in the present embodiment, since the internal MSL 6 is trimmed by a drill from the lower surface of the voltage controlled oscillator 1 not covered with the cover 12 to adjust the frequency, the electronic components on the upper surface of the voltage controlled oscillator 1 are mounted. Frequency adjustment can be performed with the cover 12 on the wiring conductor layer 3,
The frequency change due to the attachment of the cover 12 is eliminated, and the defective rate can be greatly improved. On the lower surface of the voltage controlled oscillator 1, a first ground conductor layer 4 is formed on the entire surface. When trimming is performed from this surface with a drill 62, the first ground conductor layer 4 is cut when the first ground conductor layer 4 is cut. Although burrs occur in the ground conductor layer 4, in the embodiment of the present invention, the solder resist layer 11 is provided on the first ground conductor layer 4 except for the frequency adjustment region 7, The adjustment region 7 is recessed from the surface of the solder resist layer 11 by the thickness of the solder resist layer 11. Therefore, burrs whose height is smaller than the thickness of the solder resist layer 11 do not protrude from the surface of the solder resist layer 11. Since a material having a higher hardness than the first ground conductor layer 4, for example, a nickel plating layer is formed on the first ground conductor layer 4 as a burr prevention layer 9, the frequency is adjusted by a drill for frequency adjustment. When cutting the region 7, burrs which are generated in the first ground conductor layer 4 are suppressed by the burrs 9. Therefore, large burrs protruding from the surface of the solder resist layer 11 are formed in the cutting grooves 8.
And the flatness of the mounting surface is not impaired, and poor solder connection of the voltage controlled oscillator 1 to the motherboard can be prevented.

Here, a process of forming the cutting groove 8, that is, a method of adjusting the oscillation frequency of the voltage controlled oscillator 1 will be described with reference to FIGS. First, as shown in FIG. 4, the drill 62 is cut through the burr prevention layer 9, the first ground conductor layer 4, and the base material 2 from the gold plating layer 10 and reaches the internal MSL 6. Next, while looking at a frequency monitoring device such as an oscilloscope, the rotation axis of the drill 62 or the voltage-controlled oscillator 1 is moved back and forth, and the MSL 6 is cut until the desired frequency is reached. As shown in FIG. 3, the cut groove 8 formed after the frequency adjustment is filled with the moisture-proof resin 14 within the height of the solder resist layer 11 to complete the frequency adjustment. At this time, the solder resist layer 11
May be filled with the moisture-proof resin also in the frequency adjustment region 7 in which is not formed. Although the burr prevention layer 9 and the gold plating layer 10 are formed in the above embodiment, the burr prevention layer 9 and the gold plating layer 10 need not be formed in the present invention. Further, the solder resist layer 11 may be formed so as to overlap the first ground conductor layer 4 after forming the cutting groove 8.

In the above-described embodiment, the base 2 made of a dielectric layer and having the microstrip line 6 therein, and the wiring conductor provided on the upper surface of the base 2 and mounting the electronic component 13 thereon Since the layer 3, the ground conductor layer 4 provided on the lower surface of the base material 2, and the cut groove 8 provided by cutting and reaching the microstrip line 6 from the ground conductor layer 4 were provided,
The frequency adjustment can be performed on the lower surface while the cover 12 is attached, so that the frequency change that has conventionally occurred due to the attachment of the cover 12 is eliminated, and the defect rate can be greatly improved. Further, since the solder resist layer 11 formed on the ground conductor layer 4 except for at least the periphery of the cutting groove 8 is provided, the frequency adjustment region 7 has a thickness corresponding to the thickness of the solder resist layer 11 with respect to the surface of the solder resist layer 11. The burrs that are depressed and whose height is lower than the thickness of the solder resist layer 11 do not protrude from the surface of the solder resist layer 11. Further, since a material having a higher hardness than the first ground conductor layer 4, for example, a nickel plating layer is formed on the first ground conductor layer 4 as the burr prevention layer 9, the frequency is adjusted by the drill 62 for frequency adjustment. When cutting the adjustment region 7, burrs which are generated in the first ground conductor layer 4 are suppressed by the burr prevention layer 9. Therefore, no large burrs protruding from the surface of the solder resist layer 11 are generated around the cutting groove 8, the flatness of the mounting surface is not impaired, and the voltage controlled oscillator 1
Can prevent poor solder connection.

[0016]

According to the first aspect of the present invention, since the MSL adjusting section conventionally provided on the upper surface can be eliminated, the voltage control oscillator can be downsized by reducing the amount, and the cover is attached. Frequency adjustment can be performed in the state, the frequency change due to attaching the cover is eliminated, the defect rate can be greatly improved , and the burrs that are likely to occur due to drill cutting at the time of frequency adjustment are suppressed and generated There are few burrs, and even if burrs are generated, the burrs whose height is relatively low do not protrude from the mounting surface, so the flatness of the mounting surface is maintained, and this voltage-controlled oscillator is mounted in close contact with the motherboard It can prevent poor soldering.

Further, according to the second aspect of the present invention, a change in the oscillation frequency caused by moisture absorption is prevented without absorbing moisture from the cut groove to the base material, and the oscillation frequency is kept stable for a long period of time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an entire embodiment of a voltage controlled oscillator according to the present invention.

FIG. 2 is an explanatory view of one embodiment of the voltage controlled oscillator according to the present invention as viewed from below.

FIG. 3 is an enlarged sectional view taken along line BB of FIG. 2;

FIG. 4 is an explanatory view showing a manufacturing process of one embodiment of the voltage controlled oscillator of the present invention.

FIG. 5 is an explanatory diagram viewed from the upper surface of a conventional voltage controlled oscillator.

FIG. 6 is an explanatory diagram showing a state of trimming by a drill in a conventional voltage controlled oscillator.

FIG. 7 is an explanatory diagram showing a state in which burrs are generated by a drill in a conventional voltage controlled oscillator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage control oscillator (VCO) 2 Base material 3 Wiring conductor layer 4 First ground conductor layer 6 MSL 7 Frequency adjustment region 8 Cutting groove 9 Burr prevention layer 10 Gold plating layer 11 Solder resist layer 12 Cover 12 14 Resin for moisture proof

Continuation of the front page (56) References JP-A-5-275925 (JP, A) JP-A-9-153737 (JP, A) JP-A-2-265297 (JP, A) JP-A-4-221116 (JP) JP-A-6-342965 (JP, A) JP-A-8-186349 (JP, A) JP-A-9-232143 (JP, A) JP-A-7-249874 (JP, A) 6-140764 (JP, A) JP-A-5-283933 (JP, A) JP-A-5-110319 (JP, A) JP-A-4-213204 (JP, A) JP-A-4-222201 (JP, A) A) JP-A-2-52498 (JP, A) JP-A-5-253714 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03B 5/00-5/26 H03H5 / 00-7/12 H01P 7/08 H01F H01G H05K

Claims (2)

(57) [Claims] 1. A base made of a dielectric layer and having a microstrip line therein, a wiring conductor layer provided on an upper surface of the base and mounting an electronic component, and a ground provided on a lower surface of the base. A nickel layer on the conductor layer and the ground conductor layer.
B) an anti-burr layer having a higher hardness than the ground conductor layer
And a cutting groove provided by cutting and reaching the microstrip line from the ground conductor layer, and a solder resist layer formed on the ground conductor layer excluding at least the periphery of the cutting groove. And a voltage controlled oscillator. 2. A device according to claim 1, the voltage controlled oscillator resin for moisture in the cut groove is characterized in that it is filled.