AU607005B2

AU607005B2 - An opto-electronic device

Info

Publication number: AU607005B2
Application number: AU23659/88A
Authority: AU
Inventors: Gerhard Luz; Oliver Robisch; Michael Ulmer
Original assignee: Alcatel NV
Current assignee: Alcatel Lucent NV
Priority date: 1987-10-24
Filing date: 1988-10-13
Publication date: 1991-02-21
Anticipated expiration: 2008-10-13
Also published as: EP0313956A2; AU2365988A; DE3883700D1; ATE93975T1; DE3736026A1; EP0313956A3; EP0313956B1; ES2045056T3

Abstract

An optoelectric component (1) is proposed in which the fibre end of an optical fibre (11) is coupled to a photodiode or laser diode and opaque plastic (6) is moulded around the arrangement as a whole. The basis is provided by a carrier strip which is continuously stamped from metal tape and has a mounting surface for the fibre holder and embossed mounting surfaces for the photodiode or laser diode and, if necessary, for a monitor diode. Inside the outer plastic sheath, the fibre coupling region is either embedded in transparent plastic or covered by means of a cap. An end section of the carrier strip serves as a heat-conducting plate (10) which, together with a plurality of terminal lugs (7, 8, 9) and the departing optical fibre (11), project from the plastic body (6). <IMAGE>

Description

rnA' 07 00 This docurnent Conlins the amrcndnments made under Section 49 antl is correct for printing. _I COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-1969 COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED "AN OPTO-ELECTRONIC DEVICE" The following statement is a full description of this invention, including the best method of performing it known to us:- 1 r The present invention relates to an opto-electronic device comprising an optical waveguide coupled to a photodiode or a laser diode disposed on a base part and encapsulated. Such devices are used mainly in optical communication systems.

A laser module is known whose base part is formed by the head end of a bolt. The end or the bolt has an extension of reduced cross section which serves as a root ror a laser disposed at the end or the extension. Another, pillar-like foot is mounted beside this extension in spaced relationship therefrom. It careies a solder ball with an optical waveguide embedded therein. Both foot arrangements are enclosed in a cylindrical 06 metal case one end of which is covered with a cap. The case has a lateral 0.0 0 opening in which a flanged bushing is mounted. The optical waveguide extends through this flanged bushing to in front of' the laser. The project- 9 ing end of the flanged busing is hermetically sealed by molten solder.

Behind the laser, the sidewall of the case has a further opening which con- 00 tains a mount with a photodiode fixed thereon.

0 0 c' The glass-fibre end is fixed in place when the case Is still open and the laser is on. The previously metallized end of thie optical waveguide is passed through the hole of a cold solder-tin body, and the body is placed on the pillar root. A tool holding the optical waveguide, which tool is t Z controlled by a micro-manipulator, adjusts the optical waveguide until the light power measured at its free end reaches an optimum value. Then, the solder-tin body is melted by means of a soldering fixture containing a separate laser. A solder ball is formed which, after having solidified, fixes the glass-fibre end on the pillar foot in the adjusted position.

The laser module can be manufactured only at relatively high cost. It requires a large number of relatively complex component parts whose production and assembly are expensive.

A simpler known opto-electronic device uses a metal block for the base part. The metal block consists of a base plate and a carrier on which a y.

1 p laser diode is mounted. Located behind the carrier is a mounting surface for the drive and control circuit of the laser diode, and in front of the carrier, a mounting block for holding a fibre ferrule is provided. The ferrule contains the optical waveguide, which is passed through a lateral wall opening into the interior of the housing and has its end aligned to the laser diode. The metal block rests on a plate-shaped Peltier element which is mounted on the bottom of a flat metal housing of rectangular cross section. Beside that arrangement, terminal pins sealed in pressed glass extend through the bottom of the housing, and their ends lying within the housing are connected to the laser diode and to the drive and control circuit by bonding wires. This device, too, is expensive to manufacture.

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CIC1 C C latc C~rl It is an object of the present invention to provide an opto-electronic device suitable for large-quantity production and at the same time provide a low-cost method of manufacturing.

According to the invention there is provided an opto-electronic device comprising an optical waveguide coupled to a photodiode or a laser diode disposed on a base part and encapsulated, wherein the base part is a carrier strip which is blanked out of the sheet metal, has several terminal pins and is embedded in opaque plastic with the exception of the terminalpin ends and the outgoing optical waveguide.

The proposed opto-electronic device has various advantages. It is easy and inexpensive to manufacture. The carrier strip serving as a base for the device can be formed simply by blanking and embossing. It is largely flat and accessible from all sides, thus permitting unhindered assembly and adjustment of the few component parts. The free accessibility of the mounting surfaces allows automated production with relatively simple sequences of motions. Use can be made of conventional tools and fixtures.

The encapsulating method is much less expensive than the hitherto used costly metal housings with terminal pins molded in glass.

The invention will now be described in greater detail with the aid of an embodiment illustrated in the accompanying drawings, in which: Fig. 1 is a perspective view of an opto-electronic device; Fig. 2a is a partial top view of a metal band with blanked and embossed carrier strips; Fig. 2b is a section taken along line A-B of Fig. 2a; Fig. 3a is a top view of the metal band of Fig. 2a with a tie member molded on between adjacent carrier strips; Fig. 3b is a section taken along line C-D of Fig. 3a; 10,0 Fig. 4 is a top view of the metal band of Fig. 3a with terminal pins o o o 0 0 separated at one long side of each of the carrier strips; 0 0 0 0 Fig. 5a is a top view of the metal band of Fig. 4 with fully equipped .0 o carrier strips; 0 0o°o Fig. 5b is a side view of the metal band of Fig. 5a with a 0 s0 longitudinally sectioned carrier strip, and °o Fig. 6 is a top view of the metal band of Fig. 5a with totally 0 00 00 encapsulated carrier strips; SIn Pig. 1, the opto-electronic device is designated by the reference 0 00 S Snumeral 1. It comprises a carrier strip 2 which is blanked out of sheet metal and supports a photo-diode or laser diode 3, a monitor diode 4 if 0 t 0 necessary, and a glass fibre coupled to the active area of the photo-diode or laser diode (Figs. 5a, 5b). This arrangement is embedded in plastic 6.

The plastic forms a rectangular-parallelepiped, rugged body from which the ends of several terminal pins 7, 8, 9, a heat-conducting plate 10, and the outgoing optical waveguide 11 protrude.

To manufacture the opto-electronic device 1, a metal band 12 is fed to a tool with several working stations (not shown), in which the carrier strip 2 is blanked so as to remain linked with the metal band via outer edge strips 13, 14. An intermittent feed motion of the metal band 12 resuits in a ladder-like band configuration whose rungs form the carrier t strips 2. As shown in Fig. 2a, the spaced-apart terminal pins 7, 8, 9, which lie in the sheet-metal plane and project from the carrier strip 2 on both long sides 15, 16 at right angles, are cut free during the blanking Sprocess. At the same time, a mounting hole 17 may be punched in the upper Oi portion of the carrier strip 2, which portion represents the heati conducting plate 10, and an opening 19, forming two bridge portions 18 to El be separated later, may be punched in the end portion of the heatconducting plate 10 if required.

The heat-conducting plate 10 forms one portion of the carrier strip 2, while the other portion serves as a base for mounting the fibre-coupling assembly. In the device 1, in this embodiment a laser module, an inclined C C c mounting surface 20 for the monitor diode 4 and a mount 21 for the laser C° diode 3 are embossed in a further manufacturing step in the junction region A with the heat-conducting plate 10. The mounting surface for the laser diode 3 is parallel to the plane of the carrier strip 2. The mounting surface 20 for the monitor diode 4, located between the mount 21 and the Sheat-conducting plate 10, and the plane of the carrier strip 2 inonlude an angle of 135°, so that the active area of the fixed monitor diode 4 makes an angle of 450 with the rear wide of the fixed laser diode 3.

The carrier strip 2 preferably has the same width over its entire length, and the mount 21, the mounting surface 20, and the mounting hole 17 are arranged one behind the other on the longitudinal axis of the carrier strip. The mount 21 and the mounting surface 20 are formed by striking the underside of the metal sheet with an embossing die, the mount 21 being given the shape of a frustum of a pyramid (Fig. 2b), and the mounting surface 20 for the monitor diode 4 forming a wall portion of a sheet-metal projection of triangular section, for example. In the embodiment illustrated in the drawings, the mounting surface 20 for the monitor diode 4 is produced by forming two bends in the carrier strip 2 so that the fibrecoupling portion and the heat-conducting plate 10 of the carrier strip 2 form a step.

After the blanking and embossing of the carrier strip 2, relatively short end portions of the terminal pins 7 of the carrier strip, the opposed end portions of the terminal pins 8, 9 of the previously completed carrier strip, and the edge strips 13, 14 of the metal band 12 are embedded in plastic in such a way as to form a rugged tie member 22 in the middle be- 4 tween two adjacent carrier strips 2 (Figs. 3a, 3b). Then, each of the terminal pins 8, 9 for making connections to the laser diode 3 and the monitor diode 14 is spatially separated from the carrier strip 2 by blanking a short base portion, as shown in Fig. 4.

Next the monitor diode 4 and the laser diode 3 are fixed on the mounting surface 20 and the mount 21 by adhesive bonding or soldering, and wire connections are made to the terminal pins 8, 9 by bonding.

In a separate step, the suitably prepared optical waveguide 11 is A mounted in a holder 23, such as a metallic. cable-clamp-like fibre-holding plate or a ferrule, in which the optlcal waveguide 11 Is mounted with adhesive in such a way that its stripped end 24 projects therefrom.

This assembly is transported to the carrier strip 2 and set down in the place intended for it, with the glass fibre being coarsely aligned to the laser diode 3, because the height of the mount, the mounting plane, and the fibre holder are so adapted to one another that the fibre end 24 and the active diode area form a continuous plane. After the subsequent adjustment for optimum light transmission, which is performed during operation in the conventional manner, the holder 23 is fixed on the carrier strip 2, and at least the coupling region, including the fibre end 24 and the laser and monitor diodes 3, 4, is protected by first sealing this region in transparent plastic and then embedding the carrier strip 2, including the transparent capsule, in opaque plastic 6.

6 The fibre holder 23, which is preferably formed of steel, is fixed by laser welding, for example, if the carrier strip 2 is also of steel. If the carrier strip 2 is blanked out or copper or brass sheet, the holder will be joined thereto by soldering or adhesive bonding. Fibre coupling can also be achieved by cementing the stripped fibre end 2~4 directly onto the active laser area in the optimally aligned position by means of an optical sealing compound ard simultaneously securing the optical Waveguide 11 directly to the carrier strip 2 by adhesive.

A modified manufacturing method involves covering the fibre coupling and the laser and monitor diodes 3, 14 with a hood made, for example, of plastic, and embedding the carrier strip 2 and the hollow space formed under the hood in blackened plastic 6.

Gilg The various terminal pins 7, 8, 9, the heat-conducting plate 10, the Soutgoing optical waveguide 11, an~d the portion of the edge strip 1)4 of the metal band 12 extending between the long sides 15, 16 of adjacent carrier strips 2 are left exposed.

e In the last step, the device 1 is separated from the metal band 12.

To do this, the terminal pins 7, 8, 9 and the edge strip 114 are cut through near the tie rods 22, and the bridge portions 18 are cut through at the end of the heat-conducting plate 10 (Fig. The remaining portions of the edge strip now form terminal pins 7, which can be used to make ground connections or to mount the device 1 on a mounting board.

Claims

1. A method of manufacturing an opto-electronic device including an assembly including an optical waveguide coupled to a photodiode or a laser diode, which are disposed on a base part and encapsulated in encapsulation material, the method comprising blanking out a carrier strip having two or more terminal pins and a heat-conducting plate on a metal sheet and embossing at least a first mounting surface on the carrier strip, attaching a first photodiode or a laser diode to the first mounting surface, aligning the optical waveguide with the output of the fir'st photodiode or the laser diode to optimise coupling therebetween, fixing the waveguide in the opti- mum coupling location and protecting the coupling from the ingress of the encapsulation material prior to encapsulating the assembly.

2. A method as claimed in claim 1, wherein a laser diode is mounted on the first mounting surface, the method including embossing a second mount- ing surface on the carrier strip and mounting a monitor diode on the second mounting surface, the monitor diode being located to monitor the output of the laser diode, there being an optical path between the laser diode and tle monitor diode which is protected from the ingress of the encapsulation material.

3. A method as claimed in claim 2, and wherein the laser diode has a front face from which the majority of the laser light is emitted and a rear face which is partially reflective and from which a proportion of laser light is emitted, wherein the monitor diode is aligned to receive light emitted from the rear face of the laser diode.

4. A method as claimed in any one of claims 1 to 3 wherein one or more of the terminal pins are first blanked out as integral parts of the carrier strip and then fixed in a holding means which hold the terminal pin or pins in a fixed relationship to the carrier strip, severing the fixed pin or pins from the carrier strip, connecting the pin or pins to the laser diode or photo diode, or to the laser diode or photodiode and to any other elec- tronic strip, the enc, relatio C C CCC c cC c C t CC C c rc, 4 C CC *8CCC C a c CCC CcC 4 C *s 4 *4t C II i! u .2 r u t r_ .il h m_ tronic device where there are two or more pins severed from the carrier strip, and encapsulating the resulting assembly in encapsulating material, the encapsulating material serving to hold the severed pin or pins fixed in relation to the carrier strip.

C C C ,C CC C C C cC C r i i i i;) i i t i? i: 'i v ria ii:. ri j 7 oi A method as claimed in any one of claim~ 1 to 3, wherein said car- rier strips are continuously blanked from a metal band, the carrier strips remaining linked via edge strips and bridge portions, providing the carrier strips with a seat for the photodiode or laser diode and, if necessary, with an inclined mounting surface for the monitor diode by emb~ossing, sur- rounding free ends of the opposed terminal pins of two adjacent carrier strips and portions of the edge strips of the metal band by moulded plastic material formning a tie member, spatially separating the terminal pins for the laser diode and the monitor diode from the carrier strip by blanking away short sections of the base part, providing the carrier strip with the photodiode or laser diode and, if necessary, the monitor diode, and making wire connections to the terminal pins by bonding, introducing a separately prepared optical waveguide into this arrangement, aligning the fibre end of said optical waveguide with the active area of the photodiode or laser di- ode, and fixing the optical waveguide onto the carrier strip, protecting the fibre coupling, comprising the photo-diode or laser diode, the fibre end and if present, the monitor diode, against the ingress of opaque plas- tic, and embedding the carrier strip in the plastic with the exception of the heat-conducting plate and the ends of the terminal pins, and cutting through the bridge portions, the terminal pins, and the edge strip, with the terminal pins and the edge strip being cut through near the tie mem- bers.

6. A method as claimed in any one of claim 1 to 5, wherein the op- tical. waveguide and the fibre end are mounted in a separate holding device before being aligned with the photodiode or laser diode, and that after completion of the alignment, the holding device is fixed on the carrier strip.

7. A method as claimed in any one of claim 1 to 6, wherein before the carrier strip is embedded in opaque plastic, the coupling region is embed- ded In transparent plastic. 1 V~.

8. A method as claimed in any one of claim 1 to 6, wherein before the carrier strip is embedded in opaque plastic, the coupling region is covered with a hood.

9. A method of manufacturing an opto-electronic device as herein de- scribed wit reference to the accompanying drawings.

An opto-electronic device manufactured by the method of any one of claims 1 to 9 comprising an optical waveguide coupled to a photodiode or a laser diode disposed on a base part and encapsulated, wherein the base part is a carrier strip which is blanked out of the sheet metal, has several terminal pins and is embedded in an opaque plastic housing the terminal-pin ends and the optical waveguide protruding from the housing.

11. An opto-electronic device as claimed in claim 10, wherein one end portion of the carrier strip forms a heat-conducting plate, and the other a mounting surface with the optical waveguide held thereon whose fibre end is in alignment with the photodiode or laser diode, which is fixed on a mount between the heat-conducting plate and the mounting surface.

12. An opto-electronic device as claimed in claim 11, wherein a mount- ing surface inclined to the plane of the carrier strip and having a monitor diode fixed thereon is provided between the mount for the laser diode and the heat-conducting plate.

13. An opto-electronic device as claimed in claim 12, wherein the mounting surface for the monitor diode is formed by a stepped bend in the carrier strip.

14. An opto-electronic device as claimed in any one of claims 10 to 12, including means for holding the optical waveguide comprising a fibre- holding plate mounted on the carrier strip or by a fibre ferrule.

An opto-electronic device as claimed in any one of claims 10 to 12, wherein the coupling of the optical waveguide to the photodiode or laser diode is an arrangement in which the fibre end is glued directly onto the active surface of the photodiode or laser diode and in which the optical waveguide is glued directly onto the mounting surface of the carrier strip.

16. An opto-electronic device as claimed in any one of claims 10 to wherein within the opaque plastic, a capsule of transparent plastic enclos- ing the photodiode or laser diode, the fibre end, and, if present, the mon- itor diode is disposed on the carrier strip.

17. An opto-electronic device as claimed in any one of claims 10 to wherein within the opaque plastic, the fibre coupling, comprising the photodiode or laser diode, the fibre end of the optical waveguide, and, if present, the monitor diode, is disposed in a hollow space formed on the carrier strip by a hood.

18. An opto-electronic device, substantially as herein described with reference to Figs. 1 to 6 of the accompanying drawings. DATED THIS THIRTEENTH DAY OF SEPTEMBER, 1990 ALCATEL N.V.