JP4793155B2 - Printed circuit board, printed circuit board unit, surface mount type high stability piezoelectric oscillator, and method for processing printed circuit board - Google Patents

Description

The present invention relates to an improvement of a printed circuit board and a printed circuit board unit used for a surface mount type high stability piezoelectric oscillator used as a frequency control device and the like, and in particular, a plurality of terminals erected on a lower printed circuit board for surface mounting. The present invention relates to an improvement in a terminal support structure in a piezoelectric oscillator having a structure in which an upper printed board is supported on the upper side.

Highly stable piezoelectric oscillators that can output highly stable frequencies without being affected by external temperature changes have been conventionally used as piezoelectric oscillators such as crystal oscillators, which are frequency control devices used in mobile communication equipment and transmission communication equipment. Are known. Furthermore, in recent years, in these fields, various devices have been required to be small, light, and portable, and accordingly, the highly stable piezoelectric oscillator is also required from the market to be small and light. ing.

In Patent Document 1, as shown in FIG. 4, the pin is placed on the base printed board by inserting the lower end portion of the terminal 110 having the flange 111 into the through hole 101 formed through the base printed board 100 from above. A piezoelectric vibrator (not shown) and an oscillation circuit component (not shown) are mounted on the oscillation circuit board 115 supported by the upper portion of the terminal 110 while being erected.
A surface-mount type high-stability piezoelectric oscillator that achieves miniaturization by surrounding a space on a base printed board including 15 etc. with a metal case 120 is disclosed.

In this prior art, a collar 111 provided at the bottom of the terminal by inserting the lower end of the terminal 110 into the through hole 101 in which the metal film 101b is plated on the inner wall of the through hole 101a formed in the base printed board 100. The terminal base is fixed to the land 106 on the substrate with the solder 121 in a state of being locked to the substrate surface.
However, the interior space of the through hole 101 is narrowed by the metal film 101b.
Since it is difficult to insert the pin as it is, it is necessary to secure a space for inserting the terminal 110 by drilling the metal film on the inner wall with a drill. The drilling process with a drill itself not only increases man-hours, but also burrs are formed on the metal film and chips are scattered, which may cause defects such as short circuits by attaching to other wiring patterns and parts. is there.

Also, when the lower part of the terminal 110 is inserted into the through hole 101 and cream solder is applied and then connected by reflow, the terminal falls out from the lower opening of the through hole or the solder solder is loosened or expanded during reflow. Since the pin easily tilts due to the stress due to the shrinkage, the hook 111 is provided at the lower portion of the terminal to ensure stability. However, the use of the terminal with such a hooked structure itself causes an increase in cost. .
Further, in this prior art, since the through hole 101 penetrates to the bottom surface of the base printed circuit board, when this oscillator is surface-mounted on a motherboard on the device side (not shown), it is not between the other wiring patterns. There is a risk of short circuit. In particular, there is a high possibility that a short circuit will occur due to burrs and chips generated in the metal film by the drilling process using the drill.

Next, FIG. 5 shows a conventional method of forming a recess made of a non-through hole on the surface of the base printed board and then forming a metal film on the inner wall of the recess. First, in FIG. 5A, the non-through hole 100a is formed on one surface of the printed circuit board 100, and in FIG. 5B, the base metal film 105a is formed using a required mask on the substrate surface corresponding to the opening periphery of the non-through hole 100a. Is deposited. Next, in (c), the land 105 and the recess 106 are completed by forming the plating film 105b over the surface of the base metal film 105a and the inner wall of the non-through hole 100a.
When the terminal 120 is inserted into a recess made of a non-through hole, there is no possibility of the terminal dropping downward or tilting the terminal due to reflow.
However, since the internal space of the recess 106 formed in this way is narrowed by filling the plating film 105b, there is a problem that drilling using a drill is necessary to secure a space for inserting the terminal 120. is there.
JP 2003-17940 A

As described above, in a conventional high stability piezoelectric oscillator having a two-story structure that supports an oscillation circuit board via a terminal erected on a surface mount base print board, a through-hole formed in the base print board is formed. After inserting the terminal into the hole or non-through hole, the solder was fixed by applying cream solder and heating in the reflow furnace, so that the inside of the through hole was expanded to the inner diameter suitable for the insertion of the pin There have been problems that a drilling process is required, burrs and chips are generated in the metal film in the through-hole, and that it is necessary to use an expensive terminal having a flaw.

The present invention has been made in view of the above, and since there is no need to perform a drilling process using a drill, there is no risk of increased man-hours, metal burrs or metal chips, and a flaw for preventing falling off. An object of the present invention is to provide a printed circuit board, a printed circuit board unit, a surface mount type highly stable piezoelectric oscillator, and a method for processing the printed circuit board, which can prevent the pins from falling off and tilting without using expensive pins having Yes.

In order to solve the above-described problems, a printed circuit board according to the present invention includes a printed circuit board having a surface mounting terminal at the bottom, and a recess formed on the upper surface of the printed circuit board and exposing the insulating material of the printed circuit board on the entire inner wall surface thereof. And a land provided on the surface of the printed circuit board corresponding to the periphery of the upper opening of the recess.
According to the printed circuit board of the present invention, since the conductor film is not formed on the inner wall of the recess for standing the terminal, and the land is provided on the periphery of the recess opening, the terminal is smoothly inserted into the recess. In addition, by fixing the connection between the terminal and the land with solder,
A pin can be erected in a simple process. When a conductor film is formed in the recess in advance, a drilling step for securing a space for inserting a pin is required, but according to the present invention, such trouble is eliminated.

The printed circuit board unit according to the present invention is characterized in that the printed circuit board and the terminal erected perpendicularly to the upper surface of the substrate in a state where the lower end is fitted in the recess.
According to the printed circuit board unit including the printed circuit board having the recess as described above and the terminal standingly fixed in the recess, the defective product rate of the piezoelectric oscillator to be manufactured can be greatly reduced.

The printed circuit board unit according to the present invention includes another printed circuit board supported by the upper portion of the terminal.
A printed circuit board unit having another printed circuit board on top of the pins can provide a configuration suitable for manufacturing a highly stable piezoelectric oscillator.

Further, the surface mount type high stability piezoelectric oscillator according to the present invention includes the printed circuit board unit, the piezoelectric vibrator and the heater resistance mounted on the other printed board, and the other printed board, the piezoelectric vibrator, and the heater resistance. And a metal oscillator case surrounding the space on the printed circuit board.
By using the printed circuit board unit having the terminal support structure described above, it is possible to mass-produce an oscillator with a high yield.

Further, the surface mount type high stability piezoelectric oscillator according to the present invention is such that the skirt portion of the metal oscillator case is brought into contact with the substrate exposed surface of the upper surface of the printed circuit board, and the land located on the inside of the substrate exposed surface and the substrate The outer conductor located outside the exposed surface is electrically connected by an inner conductor wired inside the printed board.
When the skirt portion of the metal oscillator case is brought into contact with the upper surface of the printed circuit board, it is effective to use the internal conductor as a means for conducting the case conductor portions that are spaced apart from the inside and outside of the skirt portion.

The printed circuit board processing method according to the present invention is a printed circuit board processing method for forming the recess and the land on the printed circuit board, wherein a conductor film constituting the land is formed on a substrate surface of the printed circuit board. And a recess forming step of forming a non-through hole reaching from the upper surface of the conductor film to the inside of the printed circuit board.
When forming a land on a printed circuit board, a base conductor film and a plating film are laminated in order, and then a recess is formed from the land surface to the inside of the board thickness. The insulating material to be exposed is exposed, and an inner diameter suitable for inserting the terminal can be secured.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.
FIG. 1 is a front view showing a configuration example of a highly stable crystal oscillator (highly stable piezoelectric oscillator) having a terminal support structure according to an embodiment of the present invention, and FIG. 2 is a terminal support structure provided on a base printed board. It is a principal part expanded sectional view for demonstrating.

This highly stable crystal oscillator 1 includes a base printed board 2 having a surface mounting terminal 3 at the bottom,
A plurality of terminals 10 erected on the base printed board 2, an oscillation circuit board 20 fixedly disposed over the terminals 10, and a crystal oscillator (piezoelectric oscillator) mounted on the oscillation circuit board 20 ) 21, a heater resistor (power transistor) 22 for heating the crystal unit 21, and circuit components 23 (oscillation circuit components, temperature compensation circuit components, etc.), and a skirt on the upper surface along the outer peripheral edge of the base printed board 2 A metal oscillator case 25 that surrounds a space on the base printed board including the oscillation circuit board 20 and the like in a state where the parts are in contact with each other.

The base printed board 2 having a multilayer structure has a recess (non-through hole) 3 on the upper surface, and the insulating material constituting the base printed board is exposed on the entire inner wall surface of the recess 7. In other words,
There is no metal film on the inner wall of the recess 7. Further, a land 4 is provided on the surface of the base printed board corresponding to the periphery of the upper opening of the recess 7. The metal oscillator case 25 is fixed in contact with the substrate exposed surface 2a on the upper surface of the base printed circuit board provided outside the land 4, and the land 4 located on the inner side of the substrate exposed surface 2a and the substrate exposed. A configuration is provided in which electrical connection is made between the outer conductor 5 located outside the surface by an inner conductor 6 wired inside the printed circuit board.

The base printed board 2 and the terminals 10 erected perpendicularly to the upper surface of the board with the lower end fitted in the recess 7 constitute a printed board unit.
Further, the base printed board 2, the terminal 10 erected perpendicularly to the upper surface of the board with the lower end fitted in the recess 7, and the solder for fixing the terminal 10 to the recess 7 and the land 4. 8 and an oscillation circuit board 20 which is another printed circuit board supported by the upper part of the terminal 10 constitutes a printed circuit board unit.

FIG. 3 is a cross-sectional view showing a processing procedure for forming the recesses 7 and the lands 4 on the surface of the base printed circuit board. FIGS. 3A and 3B show the base conductors forming the lands 4 on the insulating substrate surface of the base printed circuit board 2. A film 4a and a plating film 4b are sequentially formed. Next, in (c), the recess 7 is formed by forming a non-through hole in the insulating substrate located below the land 4 from the upper surface.

Thus, in the method for processing a printed circuit board according to the present invention, the plating film 4b is sequentially formed on the base conductor film 4a, and then the recess 7 is formed on the land 4 and the insulating substrate surface. The insulating substrate material is exposed, and the internal space of the recess is not narrowed by the metal film. Therefore, the terminal 10 can be inserted without performing a drilling process for expanding the internal space of the recess 7, and there is no possibility that metal burrs or metal chips are generated. In addition, since the lower portion of the terminal is stably supported by the recess 7, there is a possibility that the printed circuit board unit and the highly stable crystal oscillator using this unit may be deformed by tilting the pin due to the stress applied from the solder during reflow. Disappear.

Although the crystal oscillator has been described in the above embodiment, the present invention can also be applied to a piezoelectric device using a piezoelectric material other than quartz.

It is a front view which shows the structural example of the highly stable crystal oscillator (highly stable piezoelectric oscillator) provided with the support structure of the terminal of this invention. It is a principal part expanded sectional view for demonstrating the terminal support structure provided in the base printed circuit board. It is sectional drawing which shows the process sequence which forms a recess and a land in a base printed circuit board surface. It is explanatory drawing of a prior art example. It is explanatory drawing which shows the conventional method of forming the metal film on the inner wall of this recess after forming the recess which consists of a non-through hole in the base printed circuit board surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Highly stable crystal oscillator, 2 ... Base printed circuit board (printed circuit board), 2a ... Board exposed surface, 3 ... Surface mounting terminal, 4 ... Land, 4a ... Base conductor film, 4b ... Plating film, 5 ... Outer conductor, 6 ... inner conductor, 7 ... recess, 10 ... terminal, 20 ... oscillation circuit board (other printed circuit board), 2
DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator, 23 ... Circuit component, 25 ... Metal oscillator case.

Claims (6)

A printed circuit board having surface-mounted terminals on the bottom, a recess formed on the upper surface of the printed circuit board and exposed on the entire inner wall surface of the printed circuit board, and a printed circuit board surface corresponding to the upper opening periphery of the recess And a land provided on the printed circuit board. A printed circuit board unit comprising: the printed circuit board according to claim 1; and a terminal erected perpendicularly to the upper surface of the circuit board with the lower end fitted in the recess. The printed circuit board unit according to claim 2, further comprising another printed circuit board supported by an upper portion of the terminal. The printed circuit board unit according to claim 2, a piezoelectric vibrator and a heater resistor mounted on the other printed circuit board, and the other printed circuit board, the piezoelectric vibrator, and the heater resistor on the printed circuit board. A surface mount type high stability piezoelectric oscillator comprising a metal oscillator case surrounding a space. The bottom portion of the metal oscillator case is brought into contact with the substrate exposed surface of the upper surface of the printed circuit board, and between the land located inside the substrate exposed surface and the outer conductor located outside the substrate exposed surface. The surface-mounting type high-stability piezoelectric oscillator according to claim 4, wherein the surface-mounting type highly stable piezoelectric oscillator is made conductive by an internal conductor wired inside the printed circuit board. A method for processing a printed circuit board, wherein the recess and the land according to claim 1 are formed on the printed circuit board,
Forming a conductor film constituting the land on the substrate surface of the printed circuit board, and forming a recess for forming a non-through hole reaching from the upper surface of the conductor film to the inside of the printed circuit board. A method for processing a printed circuit board characterized by the above.

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