GB2174541A

GB2174541A - DIL package adaptor

Info

Publication number: GB2174541A
Application number: GB8511432A
Authority: GB
Inventors: Melvyn Paul Newbery; John Norman Haylock
Original assignee: STC PLC
Current assignee: STC PLC
Priority date: 1985-05-04
Filing date: 1985-05-04
Publication date: 1986-11-05
Also published as: GB8511432D0; GB2174541B

Abstract

An adaptor for converting a flangeless DIL package into a flanged package has a springy cover (9) which clips around the lower edge (5) of a base member (1) provided with a flange (2). The two rows of terminal pins (7) protrude freely through a pair of slots (4) in the base. <IMAGE>

Description

SPECIFICATION DIL package adaptor This invention relates to the packaging of electronic components, such as injection lasers, in dual-in-line (DIL) packages, such as a 14-pin DIL package.

In one form of DIL package, a flangeless package, the heat generated by the components of the package is designed to be ducted through the base of the package and into the surface upon which the package is mounted by way of its terminal pins. In another form of DIL package, a flanged package, the heat is designed to be ducted through a flange formed at one end of the package, this flange being designed for mounting against the side of a heatsink. Typically, though not essentially, a flanged package has a higher profile than its flangeless counter-part in order to provide a flange area more nearly the area of the base of that flangeless counterpart.

If one application for a particular component assembly requires the assembly to be packaged in the DIL package format designed for extraction of heat via the surface on which the package is mounted, while another application requires the same assembly but calls for the heat to be dissipated via a flange to a heat-sink at one end of the package, then it has been customary to make up the component assembly in both types of package format. The present invention is concerned with circumventing this requirement.

According to the present invention there is provided an adaptor for converting a flangeless dual-inline (DIL) package into a flanged DIL package, which adaptor consists of a base and a cover, wherein the base consists of a base-plate terminating at one end in a flange which constitutes the flange of the flanged DIL package, and wherein the cover is made of resilient material and has a pair of opposed sides each of which is turned inwardly and upwardly at its lower edge to form a clip for engaging around a respective one of a pair of co-operating longitudinally extending lips provided on the underside of the base-plate and so hold the flangeless DIL package pressed against the base with its terminals protruding freely through apertures formed in the baseplate.

One of the particular features of using this adaptor is that there can be a limited amount of relative movement between the flangeless DIL package and the adaptor. This means that the assembly is tolerant of small errors in the location of the terminal pin sockets of the DIL package with respect to the surface of the heat-sink against which the DIL package flange is to be clamped. This in turn means that the existence of such errors is less likely to cause any strain to be transmitted by the terminal pins to the interior of the package. Strain of this sort is undesirable because it can impair the hermeticity of the package and because it can produce misalign ment problems within the package. Such misalign ment is of particular concern in packaged electrooptic assemblies such as those incorporating an injection diode coupled to an optical fibre pigtail.

There follows a description of a DIL package adaptor embodying the invention in a preferred form. The description refers to the accompanying drawings in which: Figure 1 depicts the adaptor base, and Figure 2 depicts the complete adaptor with a flangeless 14-pin DIL package mounted inside.

Referring first to Figure 1, the base of an adaptor for converting a flangeless 14-pin DIL package into a flanged format package consists of a base-plate 1 terminating at one end in a flange 2 that constitutes the flange of the flanged format package. This base is made of material having a high thermal conductivty. In a typical example it is made of copper (suitably plated), and its base-plate is 21.0mm long, 12.9mm wide and 4.7mm high, while its flange is 25.5mm wide, 11 .0mum high and 1 .0mum thick. Two holes 3 are provided in the flange 2 for securing the flange to a heat-sink (not shown), and two slots 4 are provided in the base-plate. The slots 4 are dimensioned to give adequate clearance for the terminal pins of a flangeless DIL package mounted on the base-plate.

Longitudinal grooves extending along the underside of the base-plate define a pair of lips 5 raised slightly above the level of the bottom surface of the baseplate.

Referring now to Figure 2, a flangeless 14-pin DIL package 6 is placed on the base-plate 1 with its two rows of terminal pins 7 protruding freely through the two slots 4 of the base-plate. This particular package contains an injection laser (not shown) optically coupled with the inboard end of an optical fibre extending through an end wall of the package to form an optical fibre pigtail 8. The package is held in position by means of a cover 9 made of resilient material, such as 0.2mm thick beryllium copper sheet. The bottom edges of the two sides of the cover are turned inwardly and upwardly to form clips 10 engaging around the lips 5. The leading edges of the clips 10 may be shaped to facilitate engaging the cover around the lips 5 when sliding the cover on to the base-plate from the end opposite the flange 2. Preferably the top of the cover 9 is shaped so that it bears against the top of the DIL package 6 preferentially in regions where the top is supported by the side walls rather than in the centre of the top. This may conveniently be achieved by forming the cover with a recessed middle portion 11 whose sides are defined by two longitudinally extending bends 12. The middle portion 11 is flat before the cover is fitted, but bows resiliently outward when the clips 10 are engaged over the lips 5, this bowing providing the force that holds the package 6 pressed against the base plate 1.

Claims

1. An adaptor for converting a flangeless dual-inline (DIL) package into a flanged DIL package, which adaptor consists of a base and a cover, wherein the base consists of a base-plate terminating at one end in a flange which constitutes the flange of the flanged DIL package, and wherein the cover is made of resilient material and has a pair of opposed sides each of which is turned inwardly and upwardly at its lower edge to form a clip for engaging around a respective one of a pair of co-operating longitudinally extending lips provided on the underside of the base-plate and so hold the flangeless DIL package pressed against the base with its terminals protruding freely through apertures formed in the baseplate.

2. An adaptor as claimed in claim 1, wherein said apertures formed in the base-plate are constituted by a pair of slots each accommodating an associated one of the two rows of terminal pins of the flangeless DIL package for which the adaptor is designed.

3. An adaptor as claimed in claim 1 or 2, wherein the top of the cover is shaped to bear against the top of the flangeless DIL package preferentially in regions adjacent where the top of the DIL package is supported by the sides of the package rather than in the central region of the top of the package.

4. A DIL package adaptor substantially as hereinbefore described with reference to the accompanying drawings.

5. A semiconductor laser mounted in a dual-inline (DIL) package, and an adaptor having a DIL connection terminal format and a heat transfer mounting flange, wherein the DIL package can be connected in an external circuit either directly without the adaptor or indirectly with the adaptor.