GB2405532A

GB2405532A - Package for housing optoelectronic components

Info

Publication number: GB2405532A
Application number: GB0320089A
Authority: GB
Inventors: Martyn Owen; Andrew Thompson; Jason Gregory
Original assignee: Agilent Technologies Inc
Current assignee: Agilent Technologies Inc
Priority date: 2003-08-28
Filing date: 2003-08-28
Publication date: 2005-03-02
Anticipated expiration: 2023-08-28
Also published as: GB2405532B; GB0320089D0

Abstract

A package 40 for housing optoelectronic components (5,6,7) comprises an enclosed area 41 which is electrically connected to an open area 42, via tracks 4 through package wall 43. The enclosed area may house those components that need to be hermetically sealed, such as a laser diode. The enclosed area may be sealed using a lid (not shown). The package may be made from stacked ceramic layers. The components may be wire bonded to the base 47 of the package, which may or may not be on the same plane in both areas. The package may be connected to an external PCB 70 via interface 60. The package may be used in an electrooptical module (such as a transmitter in an optical communication system) which may operate at a speed of at least 10Gb/s.

Description

Open Back High Speed Package :.

The present invention relates to an open-back package for a high-speed optical module. . . As data communication systems increase in transmission speed the packages housing the e..

transmitter and receiver assemblies must be able to support high-speed input and/or output.... be.

signals. Typically these signals are transmitted and/or received at speeds of 10 Gb/s or greater.

These packages are often made of ceramic material via electrical tracks disposed within the. . .

structure. This is due to the fact that the electrical performance of the ceramic substrates and packages can be accurately controlled.

Figure 1 shows a known package 10 having a ceramic housing 1 with electrical tracks 4 fed through the ceramic wall 2. These tracks establish electrical connections between components 5, 6, 7 disposed within the housing and external electrical components (not shown).

For example, the tracks may establish an electrical connection between a laser disposed within the housing and a laser driver disposed on an external printed circuit board (PCB).

However, as the overall package size becomes smaller due to customer demands, fitting the components inside the housing becomes more difficult. Typically, as seen in figure 2, these components 5, 6, 7 are wire bonded 9 to the base of the package inside the housing walls 8. As the overall size of the package becomes smaller, wire bonding close to the housing walls becomes more difficult.

One possible solution is to remove certain components that do not need to be hermetically sealed inside the ceramic package and place them on an external PCB 30 as seen in figure 3. For example, the laser 5 which must be hermetically sealed to reduce exposure to moisture and thus enhance its performance and life is left inside the housing 1 while other components 6, 7 such as capacitor and amplifier are placed on the external PCB.

However, putting these components outside of the package means that highspeed connections between the components must be made via the tracks 4 on the ceramic and wire or :e tape bonding 32 to the components on the external PCB 30. This results in poorer electrical. . performance, especially at speeds of 10 Gb/s or greater. This interface 35 causes discontinuity to the RF tracks 4 and adds inductance to the module.

Thus it is an object of the present invention to overcome or at least mitigate the above- mentioned technical problems.

According to the present invention there is provided a package for housing high speed optoelectronic components thereon, the package comprising an enclosed area and an open area, said package further comprising tracks disposed thereon and arranged to electrically connect components disposed within said enclosed area with components disposed in said open area.

The package may be used in an electro-optical module. The electro-optical module may be a transmitter. The module may operate at a speed of at least 10 Gb/s. The module and/ or package may be used in an optical communication system.

The solution according to the present invention and described herein provides a package with good electrical performance up to and beyond 1 OGb/s.

While the principle advantages and features of the invention have been described above, a greater understanding and appreciation of the invention may be obtained by referring to the drawings and detailed description of an embodiment, presented by way of example only, in which: FIGURE 4 shows an open back package according to the present invention.

As seen in figure 4, the open back package 40 of the present invention comprises two areas, an open area 42 and an enclosed area 41. The enclosed area is capable of being hermetically sealed with a lid (not shown). Disposed within the enclosed area is an optoelectrical device 5, such as a laser diode, which may need to be hermetically sealed in order to operate properly, both from a performance and lifetime perspective.

In this embodiment the package itself is made up of a series of ceramic layers stacked on top of each other to create both the open and enclosed areas.

A series of electrical tracks 4 are disposed within the package and pass from the enclosed area through the package wall 43, thus making electrical connection possible between components disposed in the enclosed area and components disposed in the open area. The width of the tracks may vary as they pass through the wall in order to maintain their impedance characteristics.

The components 6, 7 disposed in the open area may be optoelectronic components, such as capacitors and amplifiers, or any component, which does not need to be hermetically sealed in order to operate correctly.

All components 5, 6, 7 may be wire bonded to the base 47 of the package. The base may be on the same plane both inside the enclosed area and in the open area. Alternatively, the base may be on different planes.

As can be seen in figure 4, the open area has only one wall 49, which limits the wire bonding of components to the base of the package. The rest of the open area wire allows for bonding to be done close to edge 48 of the base. High-speed electrical connection is maintained via the tracks 4 in the base of the package.

The base of the package could be made of metal with a ceramic tile on top, or it could be ceramic throughout.

The open area 42 of the package extends beyond the housing wall 49 to a sufficient distance so as to enable the required components to be placed on it. The base may include pads for placing the components and tracks for interfacing between the components.

An interface 60 between the components mounted on the package, both on the enclosed and open areas, and the next level of components 90 disposed on an external PCB 70 can be made using standard techniques such as wire or tape bonding. Note that the impedance matching. . is less critical for this interface and the data rate is often less than 10 Gb/s due to the use of multiplexing, thereby lessening the need for the same high quality electrical connectors that are....

needed between the components in the enclosed area of those in the open area of the package.

It is not intended that the present invention be limited to the above embodiments and other modifications and variations are envisages within the scope of the claims.

Claims

1 A package (40) for housing high speed optoelectronic components (5, 6, 7) thereon, the .

package comprising an enclosed area (41) and an open area (42), said package further comprising tracks (4) disposed thereon and arranged to electrically connect components disposed within said enclosed area with components disposed in said open area. a. .'

2 A package as claimed in Claim 1, wherein said package is ceramic.

3 A package as claimed in any preceding Claim, wherein said enclosed area is hermetically sealed.

4 A package as claimed in any preceding Claim, wherein said tracks vary in width.

A package as claimed in any preceding Claim, wherein said optoelectronic components are wire bonded to a base 47 of said package.

6 A package as claimed in Claim 5, wherein said base in said open area is on a same plane as said base in said enclosed area.

7 A package as claimed in any preceding Claim, wherein said open area is electrically connected to an external PCB.

8 A package as claimed in Claim 6, wherein said external PCB is connected to said open area via wire and/or tape bonding.

9 A package as claimed in any preceding Claim, wherein a laser is disposed in said , enclosed area.

An electro-optical module including a package as claimed in any preceding Claim.

11 An electro-optical module as claimed in Claim 10, wherein said module is a transmitter.

12 An electro-optical module claimed in Claim 10 or 11, wherein said module operates at a speed of at least 10 GHz.

13 An optical communication system comprising a package as claimed in any of preceding Claims 1-9.

14 An optical communication system comprising a module as claimed in any of preceding Claims 10-12.