GB2274831A

GB2274831A - Semi-conductor packaging tube

Info

Publication number: GB2274831A
Application number: GB9304993A
Authority: GB
Inventors: Peter Richard Ewer
Original assignee: International Rectifier Company Great Britain Ltd; International Rectifier Corp USA
Current assignee: Infineon Technologies Reigate Ltd; Infineon Technologies Americas Corp
Priority date: 1993-02-01
Filing date: 1993-03-11
Publication date: 1994-08-10
Also published as: GB9304993D0; GB9301947D0

Abstract

An electronics tube has a foil sealing member (24), which during manufacture is hermetically heat-sealed to the end of the tube. The sealing member has manually-graspable tabs (26, 28) to facilitate peeling back or removal of the foil to open the tube. The seal (24) is tamper-evident and is static-resistant. Because nothing stands proud of the faces of the tube, the tubes can be stacked for transport, and can easily be dealt with by automatic handling equipment during filling of the tube with electronics devices. <IMAGE>

Description

SE#I-CONDUCTOR DEVICE TUBES The present invention relates to semi-conductor device tubes, and in particular to the sealing of such tubes.

Semi-conductor device manufacturers generally ship their products to their customers in flat elongate plastics material tubes. A typical tube might be about 30 mm across, 6 mm deep, and 540 mm long. Such a tube might contain fifty individual electronic devices (for example power transistors), stored in one long row. When the customer receives the tube, he opens one end, tips the tube up, and the electronic devices slide out.

There have been significant difficulties in the past in finding a method of sealing the ends of the tubes.

The seals have not only to be easy for the manufacturer to secure, but also easy for the customer to undo.

Because the tubes are normally of generally rectangular section, one approach which is currently very commonly used is to drill a hole in the front and back surfaces of the tube, towards each end, as is shown schematically at 10,12 in Figure 1. A plastics pin is then pushed through one hole, and out of the other. The pin (not shown) has a head at one end preventing it from passing right into the tube, and it has an enlarged latching portion at the other so that, once it has been pushed through, it cannot accidentally fall out but has to be pulled out quite hard. During manufacture, the manufacturer inserts a pin at one end of the tube, fills the tube up with electronic devices, and then inserts another similar pin at the end, so that devices are trapped in the tube, between the pins.

A difficulty with this arrangement is that it is difficult to automate the process of pushing the pins into position. Furthermore, once the pins are in position, the heads stand proud of the surface of the tube on one side, and the latching portions stand proud of the tube on the other. This is a severe disadvantage, not only because it means that the tubes cannot easily be stacked one on top of the other during manufacture and shipping, but it also means that the tubes cannot easily be handled by automatic processing equipment, either by the manufacturer or by the customer.

What tends to happen in practice, therefore, is that the tubes are left open by the manufacturer at both ends as the devices are inserted. Once all fifty devices are in position, in the centre of the tube, the tube is carefully removed from the automatic filling equipment and the pins are pushed in at each end of the tube manually. This is not only a lengthy and tricky operation, it is also one which is fraught with danger, as it is quite easy for devices to fall out as the tubes are being removed from the automatic filling equipment.

Any devices which fall out then have to be reinserted, manually, which of course increases the possibility that tubes will go out to customers without a full complement of devices, or alternatively that one or more devices will either be mechanically or electricly damaged. The type of devices which are normally contained in these tubes are extremely susceptible to electrostatic damage, and manual handling should therefore be avoided wherever possible.

Likewise, when the filled tube arrives with the customer, he first has to remove the pins before the tubes can easily be received by his automatic handling equipment. Similar problems apply at that point.

In an effort to overcome these difficulties, some manufacturers use plastics or rubber plugs which can be pushed longitudinally into the ends of the tube. While this overcomes the automatic handling problem (there then being no part which stands proud from the sides of the tube), further problems are introduced in that such plugs have a tendency to fall out during shipping.

There are large numbers of varieties of pins which are currently in use, and also large numbers of varieties of plugs. In spite of the fact that the limitations of these methods of sealing have been known for many years, no convenient replacement has so far been proposed.

It is an object of the present invention at least to alleviate the problems of the prior art.

It is a further object to provide an improved seal for an electronics tube.

According to a first aspect of the present invention there is provided an elongate electronics device tube of generally rectangular section having opposing upper and lower walls, and opposing side walls, the tube being closed at one end by a sealing member comprising a flexible strip. The strip may have securing portions which are secured to the outside of the tube.

Alternatively, the strip may be secured by heat sealing to the end face (ie not to the side walls): the strip may then have manually-graspable flap portions, which wrap around the side walls and/or the top and bottom walls to facilitate peeling back the strip to open the tube.

If the securing portions or the flap portions lie flush with the outside of the tube, or substantially so, the tube can easily be stacked with like tubes, and can also easily be handled by automatic processing equipment.

In particular, the tube can easily be slid from one place to another, within the processing machinery, without the ends catching.

The use of a flexible strip as a sealing member, instead of a plug or a pin, means that the tube can be made slightly shorter for the same number of electronics devices.

Preferably, the tube has longitudinal guide means for holding the electronics devices in position within the tube.

The tube may if desired be hermetically sealed, or at least substantially so, to keep out dust and other contaminants. Where the tube is sealed it may be filled with clean dry air, to prevent the devices from deteriorating during transport and storage.

Alternatively, the tube may be filled with an oxygen-free gas, to prevent oxidation and subsequent deterioration of the solder. Suitable gases include nitrogen, argon or any non-reactive gas. Clean dry air might be a suitable gas if the amount of water vapour present in the tube were to be small in comparison with the amount needed to cause substantial deterioration of the solder.

According to a second aspect of the second invention there is provided a method of automatically filling an electronics tube, the tube being of generally rectangular section and having opposing upper and lower walls, and opposing side walls, the method comprising: 1. closing one end of the tube by a sealing member comprising a flexible strip; then 2. filling the tube with electronics devices from the other end; and then 3. closing the other end of the tube.

The invention may be carried into practice in a number of ways, and one specific electronics tube and its seal will now be described, by way of example, with reference to Figure 1 which shows some details of the preferred embodiment.

One end of an electronics tube, in accordance with the preferred embodiment, is shown in Figure 1. The tube is of generally rectangular section, and has identical facing sides 14,16 and upper and lower walls 18,20, the ends of which define an end face 21. The particular tube shown in the drawing is about 540 mm long, and has exterior dimensions of 32 mm x 7 mm. It will be appreciated, of course, that these dimensions are not critical and that they depend upon the size of electronics device that the tube is designed to hold.

On the opposed inner faces of the tube, about half way down the side walls 14,16 there are inwardly facing longitudinal guides 22. When the tube is filled with devices (not shown) the body of the device rests on these guides, with the thin metal legs by which the devices are, in use, connected into an electrical circuit, passing downwardly between the guides into the lower portion 30 of the tube. In this way, the fragile legs are protected from mechanical or electrical damage during transit.

The tube is of course rigid, or at least semi-rigid, to protect the enclosed devices, and it is desirably transparent so that a visual check can easily be made of the devices inside.

The ends of the tube are closed not by a pin or by a plug, but by a sealing member 32 comprising a strip of plastics coated foil 24, the ends of which are bent round to form flap portions 26,28. In one embodiment, these flap portions are not secured to the tube, but merely act as manually-graspable tabs which facilitate the user peeling back the strip to open the tube. The strip is secured to the end face 21, for example by heat-sealing.

Alternatively, the flap portions may be secured to the side walls and/or to the top and bottom walls in addition to or instead of the central section of the strip. The flap portions could also be partially secured, but with the ends free.

The tube may if desired by hermetically sealed, or at least substantially so, to keep out dust and other contaminants. Where the tube is sealed it may be filled with clean dry air, to prevent the devices from deteriorating during transport and storage.

Alternatively, the tube may be filled with an oxygen-free gas, to prevent oxidation and subsequent deterioration of the solder. Suitable gases include nitrogen, argen or any non-reactive gas. Clean dry air might be a suitable non-reactive gas if the amount of water vapour present in the tube were to be small in comparison with the amount needed to cause substantial deterioration of the solder.

In use, the manufacturer will typically cut off a small piece of plastics coated foil from a continuous roll (not shown), bend the ends over to form the flap portions 26,28, and then secure the foil to the end of the tube. The plastics coated foil is preferably heatsealable, so that the securing may be achieved merely by the operation of heat and pressure. Individual strips could also be used, rather than cutting from a roll.

In an alternative arrangement (not shown) the flap portions may wrap around the sides 14,16 instead of the upper and lower walls 18,20. It would also be possible to provide a suitably shaped sealing member having flap portions which wrap around both the upper and lower walls and also around the sides.

There is another seal at the other end of the tube (not shown) which may be identical.

The sealing member is preferably a metal foil, but it would also be possible to use simply a plastics material. The plastics material would desirably be electrically conductive to make the secured tube static safe.

Instead of heat-sealing the member to the tube, it could be sealed in any other convenient manner, such as the use of adhesive.

With the seal shown, a manufacturer can automatically seal one end of the tube, before filling the tube with devices. The automatic filling equipment can, if desired, fill the tube with an appropriate atmosphere and will then seal the other end of the tube.

The tube will then continue along the processing line, and may if required be stacked, all entirely automatically.

Once the tube reaches the customer, he simply undoes the seal by grasping one of the flap portions 26,28 and peeling the strip back. The sealing member is not easily resealable, once it has been undone, and this therefore acts as an additional security measure, assuring the customer that nobody has tampered with the devices inside the tube before he is ready to make use of them. In the past, pins or plugs were often removed, either at the manufacturers or at the customers, for example to carry out some electrical tests on one of the devices inside.

The device having been checked, it would be replaced, the tube resealed, and it would then be placed with the other tubes. As there was no way of knowing which tubes had been opened, there was at least a potential danger that a damaged device might have been put back into the tube before resealing.

If the customer wishes to do so, he can remove one of the end seals entirely, and load the tube, now open at one end only, into his automatic processing equipment.

Since the other end of the tube always remains sealed, there is no danger of devices falling out the wrong way.

With the device of the present invention, there is no need for the holes 10,12 which would previously have received a pin.

Claims

CLAIMS:

1. An electronics device tube, containing electronic devices, the tube being hermetically sealed.

2. A tube as claimed in Claim 1 in which the tube is filled with a non-reactive gas.

3. A tube as claimed in Claim 1 or Claim 2 in which the gas is dry air, the amount of available water vapour not being sufficient to cause substantial deterioration of the devices.

4. A tube as claimed in Claim 1 or Claim 2 in which the gas is nitrogen.

5. An elongate electronics device tube of generally rectangular section having opposing upper and lower walls, and opposing side walls, the tube being closed at one end by a sealing member comprising a flexible strip.

6. A tube as claimed in Claim 5 in which the flexible strip is bent to form a central section, which closes the end of the tube, and two flap portions which overlie the ends of the upper and lower walls or the ends of the side walls.

7. A tube as claimed in Claim 6 having four flap portions, each of which overlies an end of a respective wall.

8. A tube as claimed in any one of Claims 5 to 7 in which the flexible strip is electrically conductive.

9. A tube as claimed in Claim 8 in which the flexible strip is of metal foil.

10. A tube as claimed in Claim 8 in which the flexible strip is of a plastics-coated foil.

11. A tube as claimed in any one of Claims 5 to 8 in which the flexible strip is of a plastics material.

12. A tube as claimed in any one of Claims 5 to 11 in which the sealing member is tamper-evident.

13. A tube as claimed in any one of Claims 5 to 12 in which the sealing member is heat sealed to the tube.

14. A tube as claimed in Claim 6 or Claim 7 in which the flap portions are secured to the ends of the upper and lower walls and/or to the ends of the side walls.

15. A tube as claimed in Claim 6 or Claim 7 in which the flap portions are adapted to be manually grasped to facilitate opening or removal of the strip.

16. A tube as claimed in any one of Claims 5 to 15 in which the sealing member is secured to an end face of the tube.

17. An elongate electronics tube substantially as specifically described, with reference to Figure 1, but excluding reference to the holes (10,12).

18. A method of automatically filling an electronics tube, the tube being of generally rectangular section and having opposing upper and lower walls, and opposing side walls, the method comprising:

1. Closing one end of the tube by a sealing member comprising a flexible strip; then

2. filling the tube with electronics devices from the other end; and then

3. closing the end of the tube.

19. A method as claimed in Claim 18 in which the strip is secured to an end face of the tube.

20. A method as claimed in Claim 18 or Claim 19 including the step of first cutting the or each flexible strip from a continuous roll.

21. A method as claimed in any one of Claims 18 to 20 in which the strip is heat-sealed to the tube.

22. A method as claimed in any one of Claims 18 to 21 including the step of automatically stacking the filled and closed tube on a stack of previously closed and filled tubes.

23. A method as claimed in any one of Claims 18 to 22 including hermetically sealing the tube at both ends.

24. A method as claimed in Claim 23 including filling the tube with a desired non-reactive gas before closing and hermetically sealing the said other end of the tube.

25. A method of automatically filling an electronics tube, substantially as specifically described, with reference to Figure 1.