JP2003101283A - Device for mounting substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for mounting a substrate which is excellent in shielding property. SOLUTION: A connector 5 is constituted so that the bottom unit of a housing 1 is contacted closely with a circuit substrate 6 when the connector 5 is engaged with a partner connector 7 on the circuit substrate 6, by a method wherein the connector 5 for taking out a signal from electric parts 25 in the metallic housing 1 for receiving the electric parts 25 to the circuit substrate 6 outside of the housing 1 is provided so as to be faced to the bottom unit of the housing 1. An inlet port 26 for inserting the partner connector 7 into the bottom surface of the housing 1 is formed on the bottom surface of the housing 1, and a conductive gasket 81, contacted closely to the circuit substrate 6 is attached to the circumference of the inlet port 26. A gap upon engaging the connectors is eliminated by the gasket 81.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board mounting device mounted on a circuit board by fitting a connector,
In particular, the present invention relates to a substrate mounting device having excellent shield properties.

[0002]

2. Description of the Related Art When a device containing electric parts or other parts in a housing is attached to a base material such as a printed circuit board, it is permanently fixed by soldering or a socket fixed to the printed circuit board. In some cases, it may be attached to and detached from a fixture (also an electrical connector). Here, the latter type of device is referred to as a substrate mounting device.

An optical communication device will be described as an example of a substrate mounting device.

In optical communication, an optical transmitter and an optical receiver for mutually converting an optical signal in an optical fiber transmission line and an electric signal in a communication processing device are required. An integrated optical transmitter and optical receiver is called an optical transceiver. Here, the optical transmitter, the optical receiver, and the optical transceiver are collectively referred to as an optical communication device.

In general, the optical transceiver, as shown in FIG. 10, drives one light emitting module by an electric signal to output an optical signal, and one transmitting unit 101 which converts the optical signal into an electric signal by a light receiving module. It is one united with one receiving unit 102 for amplification.

The optical transceiver is mounted as a component on a circuit board that performs communication processing. Further, the circuit board is housed in the housing of the communication processing device.

In the conventional optical transceiver, as shown in FIG. 11A, a single optical element 111 is packaged.
The optical element module 118 is configured by mounting the leads 112 in the package 112 of the optical element module 118, and the optical element module 118 is attached to the substrate 119 in the optical transceiver as shown in FIG. 11B. Has been done. Reference numeral 114 is a lens that focuses the light on the optical element, 115 is a mount base that fixes the optical element, and 116 is wire bonding that connects the optical element to the lead. Package 112
The optical fiber 117 inserted into the optical fiber 117 is of the integrated optical fiber type. Further, 109 is a wiring pattern of the optical transceiver board, and 108 is an IC module for processing an electric signal. In the IC module 108, FIG.
As shown in (c), the IC chip 107 is housed, and the IC chip 107 is connected to the wire bonding 106.
Is connected to the lead 105 via.

In order to couple the optical fiber of the transmission line to the optical element module 118, as shown in FIG. 12, a housing 123 of the optical transceiver 121 is provided with a receptacle 123 into which an optical fiber connector is inserted. The optical transceiver 121 having such a configuration is called a receptacle type. The optical transceiver 121 is arranged and mounted on the circuit board so that the end surface of the receptacle 123 is located at the end of the circuit board.
The circuit board is arranged so that the end surface of the circuit board opens from the front panel of the housing of the communication processing device. However, it is also possible to realize a pigtail type in which the optical fiber 117 directly coupled to the optical element module is extended from the optical transceiver without using the receptacle and the connector is attached to the optical fiber 117.

As a method of electrically connecting and mechanically fixing the optical transceiver 121 to the circuit board, the lead 124 extending from the housing 122 of the optical transceiver 121 is used.
There is a method of soldering to the circuit board. In the case of the pigtail type, a male and female connector may be mounted on the housing of the optical transceiver and the mating circuit board, and the connectors may be fitted together.

The pigtail type optical communication device mounted by the connector as described above is a substrate mounting device.

[0011]

The electric signals in the transmitter and the receiver have a high frequency. When handling high-frequency signals, it is necessary to take care so that unwanted radiation does not adversely affect peripheral circuits and equipment. Therefore, it is effective to configure the housing with a metal such as aluminum.

However, in the case where a male and female connector is mounted on the housing and the mating circuit board and the connectors are fitted to each other, even if the housing is made of metal, this housing is used as the circuit board. If a gap is formed between the bottom surface of the housing and the circuit board in the mounted state, unnecessary radiation will leak from this gap.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a substrate mounting device having excellent shielding properties.

[0014]

In order to achieve the above object, the present invention provides a connector for taking out a signal from an electric component to a circuit board outside the housing in a metal housing for accommodating at least the electric component. By being provided so as to face the bottom of the housing, the bottom of the housing is in close contact with the circuit board when the connector for connection is fitted to the mating connector on the circuit board, and the bottom of the housing is formed. In addition to forming an inlet into which the mating connector is inserted, a conductive gasket that is in close contact with the circuit board is attached around the inlet.

A groove into which the gasket is fitted may be formed at the location where the gasket is attached on the bottom surface of the housing.

The gasket may be obtained by applying a liquid gasket raw material to the bottom surface of the housing and solidifying the gasket raw material.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, an optical communication device, which is a device for mounting a substrate according to the present invention, has a multicore flat optical fiber (also referred to as a tape fiber) in a housing 1 containing a plurality of optical elements and IC chips. ) 2 is inserted, and a multi-core collective optical connector 3 is attached to the opposite end of the multi-core flat optical fiber 2 in a pigtail type optical communication device. In the housing 1, each optical element is arranged so as to face the optical fiber of each core of the multicore flat optical fiber 2.

Here, as the multicore flat optical fiber 2, an 8-core flat optical fiber in which single-mode fibers φ0.25 mm × 8 are arranged in parallel at a pitch of 0.25 mm is used. One end of the 8-core flat optical fiber 2 is inserted into the housing 1 and fixed in the housing 1. An 8-core collective optical connector 3 is attached to the opposite end of the 8-core flat optical fiber 2.

The housing 1 is made of metal (aluminum) and has a substantially rectangular parallelepiped shape. A release member 4 for tilting the optical communication device when the optical communication device is removed from the host circuit board is provided at the end of the housing 1 opposite to the insertion end of the multi-core flat optical fiber.

Inside the housing 1, a connecting connector 5 is housed so as to face the bottom. This connector 5 is for taking out a signal from the IC chip to the host circuit board 6 outside the housing and fixing the optical communication device to the host circuit board 6. If the connector 5 is a female, the host The mating connector 7 on the circuit board 6 is male. The male and female of the connecting connector 5 and the mating connector 7 may be reversed.

As shown in FIG. 2, the housing 1 of the optical communication device according to the present invention is divided into a lower housing 21 and an upper housing 22. Of these, the lower housing 21 is composed of a bottom surface and side walls surrounding the periphery thereof, and forms a space for accommodating the optical communication device substrate 23. The upper housing 22 closes the upper part of the accommodation space and forms a large number of irregularities (not shown) on the surface to radiate heat.

On the optical communication device substrate 23, a wiring pattern is formed on the surface, and an optical element substrate (silicon substrate) 24 and an IC chip 25 are mounted. The connector 5 for connection is attached to the back surface of the optical communication device substrate 23.

A mating connector 7 is provided on the bottom surface of the housing 1.
Is formed with an inlet 26. Since the lower end of the connecting connector 5 is located at substantially the same height as the inlet 26, when the connecting connector 5 is fitted to the mating connector 7, the bottom surface of the housing 1 substantially contacts the host circuit board 6. Become.

A plurality of optical elements 27 are provided on the optical element substrate 24.
Are mounted side by side on a straight line. These optical elements 27
And the IC chip 25 are connected by wire bonding 28. Further, the tip of the multi-core flat optical fiber 2 is placed and fixed on the optical element substrate 24. By closing the upper portion of the lower housing 21 with the upper housing 22, the multicore flat optical fiber 2 is inserted into the housing 1 from the closed portion of the upper and lower housings.

An optical element 27 is arranged in the housing 1 so as to face the insertion end of the multi-core flat optical fiber 2, an IC chip 25 is arranged on the back side of these optical elements 27, and further, the IC chip 25 of the IC chip 25 is arranged. The connector 5 for connection is arrange | positioned at the back.

As shown in FIG. 3, inside the optical communication device according to the present invention, eight optical elements 27 are arranged in a line on the optical element substrate 24 at a minimum pitch of 0.5 mm. (Only three are shown in this figure for simplicity). V-grooves 31 are formed in advance on the optical element substrate 24 at the same pitch of 0.5 mm as the arrangement pitch of the optical elements 27. One optical fiber 32 along each V groove 31
, And each optical fiber 32 is fixed to the optical element substrate 24 by adhesion.

Each optical element 27 and each terminal of the IC chip 25 are connected by wire bonding 28. In addition, a wiring pattern 33 is previously formed on the surface of the optical communication device substrate 23.
Are formed, and the wiring pattern 33 is connected to each terminal of the connecting connector 5. And IC chip 2
The terminals 5 and the wiring patterns 33 are connected by wire bonding 34.

Although the optical element 27 is not limited to a light emitting element or a light receiving element up to now, all the eight optical elements 27 are light emitting elements and the IC chip 25 is an eight circuit driver. The device is an 8-channel optical transmitter, and all eight optical elements 27 are light receiving elements.
By using the C chip 25 as an 8-circuit amplifier, this optical communication device becomes an 8-channel optical receiver. Also,
The light emitting element and the light receiving element are used in combination, and I
An optical transceiver that performs 4-channel transmission / reception may be formed by mounting the C chip and the IC chip of the amplifier.

Further, the number of channels is set to 8 in accordance with the convention that the computer constituting the communication processing unit has a unit of 8, and it goes without saying that another number may be used.

The optical communication device of the present invention shown in FIGS. 1 to 3 is of the pigtail type and uses the single optical element 27 or the IC chip 25, so that the occupied space per circuit can be reduced. Further, since the optical element 27 is arranged so as to face the optical fiber 32 of each core and the IC chip 25 is arranged on the back side of the optical element 27, a narrow optical communication device is formed, and on the host circuit board 6. It becomes possible to arrange them densely. In addition, since the optical element 27 and the IC chip 25 are connected by the wire bonding 28, the number of joints is small, the reliability is high, and the transmission distance in the optical communication device is short. Unnecessary radiation is less likely to be emitted between the insides of the devices, and is less likely to be received.

As a result, it is possible to realize an 8-channel optical transmitter or an optical receiver or a 4-channel transmission / reception, which is approximately the same size (end face width: about 13 mm) as the conventional 1-channel transmission / reception optical transceiver. .

Next, the arrangement of the optical elements will be described.

In the arrangement shown in FIG. 4A, eight single optical elements 27 are arranged on the optical element substrate 24 in a row at equal intervals. The optical fibers 32 forming the cores of the 8-core flat optical fiber 2 are arranged at the same pitch as the optical elements 27, and are optically coupled to the optical elements 27 one-to-one.

In the arrangement shown in FIG. 4 (b), a four-element array 42, in which four optical elements are arranged in a row and integrated, is mounted on each of the two optical element substrates 41, 41. There is. By arranging two 4-element arrays 42 in this manner, eight optical elements are arranged in a line.

When a composite of a large number of elements such as an 8-element array is used, the number of mounting steps can be saved, but the array must be replaced even if one element is defective, resulting in poor yield. On the other hand, when a plurality of single optical elements 27 are used, only the optical element 27 needs to be replaced in the case of a defect, so the yield is improved, but the single optical elements 27 are aligned and mounted one by one. Takes man-hours. 4-element array 42
When using a composite of a small number of elements such as, the probability that one of the elements will be defective is lower than the composite of a large number of elements,
The yield does not drop so much, and the mounting man-hour is reduced, so that the cost can be reduced as a whole. In addition, FIG. 4 (a) using the single optical element 27
Which of the above-mentioned form and the form of FIG. 4B using the 4-element array 42 is superior in cost is judged by comparing the unit price of each component, the yield rate, the mounting man-hour and the unit price. It will be.

The circuit diagram of the optical communication device of the present invention is shown in FIG.
It becomes like (a) or FIG.5 (b). In the circuit shown in FIG. 5A, all eight optical elements 27 are light emitting elements, for example, LD (laser diode) 51, and the IC chip 25 is a drive circuit array 52 of eight circuits. As a result, an 8-channel optical transmitter is realized.

In the circuit shown in FIG. 5B, all eight optical elements 27 are light receiving elements, for example, PDs (photodiodes) 53, and the IC chip 25 is an amplification circuit array 54 of eight circuits. As a result, an 8-channel optical receiver is realized.

In the optical communication device of FIGS. 5A and 5B, the functions of optical elements and circuits are unified, so that a plurality of necessary circuits can be realized by one IC chip 25. . As a result, the number of parts accommodated in the housing is reduced, which leads to downsizing and cost reduction.

Two transmission lines for transmitting and receiving signals from the IC chip 25 to the host circuit board 6 via the connection connector 5 are wired for one signal. Then, the signal logic of one transmission line is inverted from the signal logic of the other transmission line for transmission. FIG. 6A shows an example of the optical transmitter.

As shown, a signal "data" is output from two adjacent connector terminals 61 and 62 in the connector 5 for connection.
And the signal “data bar” are input for one drive circuit 63. Although the shape of the wiring pattern is not shown, the wiring pattern of the signal "data" and the wiring pattern of the signal "data bar" are provided close to and adjacent to each other, preferably in parallel. The drive circuit 63 causes the LD 51 to emit light only when the signal “data” is 0 and the signal “data bar” is 1, and does not cause the LD 51 to emit with other logics. The signals "data" and "data bar" from the host circuit board 6 always have opposite logics as shown in FIG. 6 (b).

In the case of an optical receiver (not shown), the PD output is input to the amplifier circuit, and the signal "data""databar" of the forward and reverse logic is output from the amplifier circuit. The wiring pattern of the signal “data” and the wiring pattern of the signal “data bar” are provided close to and adjacent to each other, preferably in parallel, and are connected to two adjacent connector terminals in the connection connector 5.

As described above, since two signal transmission lines are wired for one signal and the signals are transmitted with their logics being inverted from each other, the radiation noise from both lines becomes negative when one is positive and the other is negative.
The radiant spaces slightly apart cancel each other out. This eliminates crosstalk with other signal transmission lines.

Next, a mode in which the optical communication device of the present invention is used in a communication processing apparatus will be described.

As shown in FIG. 7A, the host circuit board 6 is a slot insertion type board having a backboard connector 71 at one end. This host circuit board 6
A plurality of mating connectors 7 are mounted on each of the mating connectors 7, and an optical communication device 72 can be attached to each mating connector 7. The arrangement of the optical communication devices 72 shown in the figure is such that the longitudinal directions of the housings 1 are parallel to each other, and the optical communication devices 72 are arranged in one or more rows near the free end of the host circuit board 6. Housing 1 is a multi-core flat optical fiber 2
Is inserted toward the backboard connector 71, and the multicore collective optical connector 3 on the opposite end of the multicore flat optical fiber 2 extended from this is inserted into the backboard connector 71. A communication processing circuit is mounted between the backboard connector 71 and the optical communication device 72.

Each optical communication device 72 is the 8-channel optical transmitter or optical receiver described so far,
Since the size is almost the same as that of the channel optical transceiver, if the host circuit board 6 has the same area, four times as many channels as the conventional one can be mounted.

As shown in FIG. 7B, the communication processing device 73 has a multistage slot 74 into which a plurality of boards can be inserted, and a plurality of host circuit boards 6 can be mounted. Of course, a communication processing device including one host circuit board 6 may be configured. An optical fiber cable 75 is wired from the back side of the communication processing device 73 to another communication processing device (not shown). This enables multichannel optical communication with another communication processing device.

FIG. 7C shows a backboard connector 71.
2 shows an example of the connection relationship between the multi-core flat optical fiber 2 from one optical communication device 72 and the optical fiber cable 75 wired from the back side of the communication processing device 73. The multicore flat optical fiber 2 includes an optical transmission line from the first channel ch1 to the Nth channel chN. On the other hand, the optical fiber cable 75
, Each channel is independent, and is wired to a plurality of communication partners 76. In this way, each channel in one optical communication device 72 can be independently wired to any communication processing device. Therefore, when the number of channels required for each communication processing device that is the communication partner 76 is different, it is possible to allocate any channel of the optical communication device 72 to any communication processing device that is the communication partner 76. Become. As a result, for example, it becomes easy to wire a large number of terminals, relay devices, and optical fiber cables from other host devices to the LAN host device.

Next, the features of the bottom surface of the housing of the optical communication device according to the present invention will be described in detail.

As shown in FIG. 8, an inlet 26 for inserting the mating connector 7 is formed on the bottom surface of the housing 1. Since the lower end of the connecting connector 5 is located at substantially the same height as the inlet 26, when the connecting connector 5 is fitted to the mating connector 7, the bottom surface of the housing 1 substantially contacts the host circuit board 6. Become.

A conductive gasket 81 is attached to the bottom surface of the housing 1 around the inlet 26. The gasket 81 is formed in a substantially rectangular shape using a line of a predetermined width so as to surround the outer periphery of the inlet 26.

The gasket 81 is obtained by, for example, applying a liquid gasket raw material to the bottom surface of the housing 1 and solidifying the gasket raw material. Also, the gasket 81
May be made of conductive rubber.

The sectional structure near the bottom of the housing 1 will be described with reference to FIG. The upper part of the housing 1 is closed by an upper housing 22 which also functions as a heat dissipation plate,
The lower housing 21 also includes a side wall and a bottom surface, and only the inlet 26 formed on the bottom surface is a portion open to the outside. A groove 91 is formed on the bottom surface of the housing 1 so as to surround the inlet 26. Gasket 8 to fit in groove 91
No. 1 has a substantially circular cross section, and has a diameter slightly larger than the depth of the groove 91. As a result, the gasket 81
When is fitted in the groove 91, a part of the gasket 81 is slightly projected from the bottom surface of the housing 1.

On the other hand, a ground pattern 92 is formed on the host circuit board 6 so as to face the rectangular frame-shaped portion of the bottom surface of the housing 1 excluding the inlet 26. The ground pattern 92 surrounds the mating connector 7. When the connecting connector 5 is fitted to the mating connector 7, the gasket 81 comes into close contact with the ground pattern 92 and seals the gap between the bottom surface of the housing 1 and the host circuit board 6.

In this way, the gap for leaking radio waves is surely eliminated, and the metal housing 1 forming the shield is electrically connected to the ground pattern 92 with a wide contact area via the gasket 81. Is surely at ground potential.

In the above embodiments, the optical communication device is taken as an example, but the present invention can be applied not only to the optical communication device but also to a substrate mounting device which is attached to and detached from the mother body by a socket or a connector.

[0057]

The present invention exhibits the following excellent effects.

(1) Since the connector for connection is provided in the metal housing and the inlet for inserting the mating connector is formed on the bottom surface of the housing, both connectors are surrounded by the housing in the fitted state and are shielded against radio waves. To be done. Even if the bottom of the housing does not come into close contact with the circuit board due to dimensional error, the conductive gasket surrounds the periphery of the inlet, so there is no gap for radio wave leakage. Further, since the gasket contacts the ground pattern of the circuit board, the housing can be surely grounded.

(2) Since the groove for fitting the gasket is formed, the fitting is easy.

(3) Since the liquid gasket raw material is simply applied to the bottom surface of the housing, the mounting is easy.

[Brief description of drawings]

FIG. 1 is an external view of an optical communication device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an optical communication device showing an embodiment of the present invention.

FIG. 3 is an internal structural diagram of an optical communication device showing an embodiment of the present invention.

FIG. 4 is a layout view of an optical element showing an embodiment of the present invention.

FIG. 5 is a circuit diagram of an optical communication device showing an embodiment of the present invention.

FIG. 6A is a circuit diagram of one channel and FIG. 6B is a signal waveform diagram in the optical communication device according to the embodiment of the present invention.

FIG. 7 is (a) a configuration diagram of a host circuit board, (b) a mounting diagram of the host circuit board, and (c) a channel distribution diagram in the communication processing device according to the embodiment of the present invention.

FIG. 8 is an external view in which the bottom surface of the optical communication device according to the embodiment of the present invention can be seen.

FIG. 9 is a lateral cross-sectional view of an optical communication device showing an embodiment of the present invention.

FIG. 10 is a circuit diagram of a conventional optical transceiver.

FIG. 11 is (a) an internal structure diagram of an optical element module, (b) a physical layout diagram of an optical transceiver substrate, and (c) an internal structure diagram of an IC module in a conventional optical transceiver.

FIG. 12 is an external view of a conventional optical transceiver.

[Explanation of symbols]

1 housing 2 Multi-core flat optical fiber 4 Release member 5 Connector for connection 6 Host circuit board 7 Mating connector 25 IC chip 26 entrance 27 Optical element 81 gasket 91 groove 92 Grand pattern

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Mizobuchi             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center (72) Inventor Ryuta Takahashi             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center (72) Inventor Kenichi Tamura             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Cable Co., Ltd., Optro System Research Center F-term (reference) 5E321 AA01 AA02 AA03 CC02 GG09

Claims (3)

[Claims] 1. A connector for taking out a signal from the electric component to a circuit board outside the housing is provided in a metal housing for accommodating at least the electric component so as to face the bottom of the housing, thereby providing the connector for connection. The housing bottom is configured to be in close contact with the circuit board when fitted to the mating connector on the circuit board, and an inlet for inserting the mating connector is formed on the bottom surface of the housing. A device for mounting a substrate, characterized in that a conductive gasket that is in close contact with the circuit substrate is attached around the entrance. 2. The board mounting device according to claim 1, wherein a groove into which the gasket is fitted is formed at a location where the gasket is attached on the bottom surface of the housing. 3. The substrate mounting device according to claim 1, wherein the gasket is obtained by applying a liquid gasket raw material to the bottom surface of the housing and solidifying the gasket raw material.