GB2127380A

GB2127380A - Packaging tubes for electronic components

Info

Publication number: GB2127380A
Application number: GB08310536A
Authority: GB
Inventors: Yun Kai Lee; Stanley Kwok
Original assignee: Peak Plastic & Metal Prod
Current assignee: Peak Plastic & Metal Prod
Priority date: 1982-08-10
Filing date: 1983-04-19
Publication date: 1984-04-11
Also published as: GB2127380B; GB8310536D0

Abstract

An antistatic packaging tube containing electronic components (12), especially DIL encapsulated integrated circuits, and having a window 32 of transparent material along its length is so designed, co- relative to the shape of the packaged components (12), that the components (12) cannot come into contact with the material of the window 32. In this way the component 12 is less likely to be damaged by static electric charges on the window 32. There may be two such windows 32, 32a, Figs 8-11 (not shown), which strengthens the tube since the window material is stronger than the antistatic material of the rest of the tube. Preferably both clear and opaque antistatic materials are extruded together to form the tube, using apparatus with two or three main extruder screws (43, 43a, 44), Figs. 14-16 (not shown). <IMAGE>

Description

SPECIFICATION Packaging tubes for electronic components This invention relates to packaging tubes used for holding electronic components in transit and to a method of producing such tubes. In particular, although not exclusively, the invention is concerned with carrier tubes for compojnents in dual-in-line (DIL) encapsulation.

In the electronics industry it is often necessary to pack and transport large numbers of components encapsulated in the so-called DIL encapsulation, the majority being integrated circuits (I.C.'s). The DIL encapsulation consists of a fairly flat rectangular body in which the I.C. or other component(s) is encapsulated, with short connecting leading pins descending from the two longer sides of the encapsulation.

To pack and transport these DIL encapsu- lated compone ts there are currently provided hollow elongate carrier tubes which generally have a cross se tion which is substantially trapezoidal with an inward projection from the longer parallel side of the trapezium. The components are slid into the tube straddling this projection. Normally such packaging tubes fully encircle the electronic components.

The tubes may be required to have an antistatic property to protect the electronic components from possible damage by static electricity building up on the tube. This antistatic action can be providing by the use of carbon black, usually with either polystyrene or polypropylene as tube material. The carbon black leads to a tube having antistatic properties, but which is also opaque, making it impossible to see how many electronic components are contained in the carrier tube.

UK Patent Specification 1 593760 discloses the use of a tube in which a top portion is transparent. The remainder of the tube contains carbon particles so as to be conductive.

The tube is made from PVC (polyvinylchloride). This tube thus has an electrically conductive opaque portion and a transparent portion providing a window along the length of the tube. This window however is not electrically conductive, so that the components can contact both conductive and non-conductive tube regions.

Broadly in this invention we provide a tube in which a window of light transmitting material is provided, but the components are prevented from touching the non-conductive areas represented by such windows of light transmitting material.

More specifically, this invention provides a packaging tube for electronic components of predetermined form, the tube comprising opaque antistatic material and having at least one window of light transmitting material, providing along the length of the tube means for seeing electronic components in the tube, the shape and size of the tube correlative to said electronic components of predetermined form being such as to prevent contact between said components and said light transmitting material when said components are packaged inside the tube.

In one prefered arrangement a window is recessed from a flat inner surface of the tube, so that inside the tube this inner surface stands proud of the window while outside the tube the window stands proud. In another arrangement a window lies between two projections into the interior of the tube.

In the tubes of this invention it is prefered that there is a continuous window extending along the tube, but it would be possible to employ a succession of windows along the length of the tube. The tube may possibly have the antistatic material as a separate layer, such as a coating on the internal surfaces of the tube walls. However, in a preferred arrangement the tube has walls formed of the opaque antistatic material with a window of light-transmitting material integral with them.

The invention embraces a method of making such a tube, comprising the steps of forming streams of molten opaque antistatic material and light transmitting material, and advancing these streams by means of respective feed screws, feeding the streams to different parts of a passage leading to an extrusion orifice, letting them merge in the passage and extruding them together as a tube with a window, which tube can be shaped further while it is still soft.

We prefer to use PVC as the tube material, incorporating carbon black to provide the antistatic property, because of the greater rigidity of PVC which enables the thickness of the tube body to be reduced as compared with the thickness necessary when polystyrene or polypropylene is used.

The packaging tube of this invention may in particular be an extruded packaging tube for integrated circuits in dual-in-line encapsulation, the tube being hollow, elongate and of a uniform cross-section which includes an internal projection to be straddled by the components. The preferred cross-section for such a tube has a pair of spaced apart substantially parallel edges and a pair of mutually diverging edges extending between them to define substantially a trapezium, the aforesaid projection to be straddled by the components being substantially rectangular in section and extending inwardly from the longer parallel edge of the trapezium. It is then preferred that the or a window is in the shorter parallel edge of the trapezium.

It is possible to provide more than one window. In particular, a first window can be provided extending along the length of the shorter parallel side of the trapezium and a second window can be provided extending along the length of the top St rtace of the projection from the longer parallel side, the tube being shaped to prevent components from touching either window. One advantage of two windows is that it strengthens the tube, because conductive PVC is not as strong as transparent PVC.

Embodiments of the present invention, given by way of example, will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of one end portion of a packaging tube; Figure 2 is a somewhat diagrammatic crosssection of the tube of Fig. 1; Figure 3 to 7 shows further possible crosssections for tubes embodying the present invention and each having a single longitudinal window; Figures 8 to 13 show possible cross-sections for tubes embodying the present invention and each having two longitudinal windows; Figure 14 is a sectional view of an extruder head for producing packaging tubes formed from opaque antistatic plastic and from transparent plastic, having a single longitudinal window; Figure 15 is a sectional view along the line XV-XV of the extruder head shown in Fig.

14; Figure 16 is an end view of the extruder head die shown in Fig. 14 looking in the direction of arrow XVI; Figures 17 to 19 correspond to Figs. 14 to 1 6 respectively for an extruder head for producing packaging tubes having two longitudinal windows; Figure 20 shows a die for producing packaging tubes in association with the extruder head shown in Fig. 14; Figure 21 is a sectional view on line XXI-XXI of the die shown in Fig. 20.

Referring first to Fig. 1 of the drawings the packaging tube shown is an elongate tube formed by extrusion of the plastics material from which it is made. The tube has a uniform cross-section and as can be seen from Fig. 2 this cross-section comprises a side 2, shown at the top, mutually inclined sides 4, 6, a side 8 parallel to the side 2, but longer, and a projection 10 of rectangular section which extends into the tube from the longer parallel side 8. The sides 2, 4, 6, 8, define substantially a trapezium shape. The tube is used to carry integrated circuits 12 (Fig. 2) in dual-in-line encapsulation. These are packed into the tubes straddling the projection 10 so that the body 14 of the encapsulation rests on the projection 10 and the connecting pins 1 6 lie at each side of it.The integrated circuits are retained in the packaging tubes by pins 20 inserted through holes punched at each end of the tube.

The tube shown in Figs. 1 and 2 is primarily formed from rigid PVC which incorporates carbon black thus giving the tube an antistatic property but at the same time rendering it opaque. This opaque PVC is shown shaded in Fig. 2 and forms the margins 31 of the top wall, the base 8 the projection 10 and the walls 6, 4. Thus they are a single-wall, conductive, carbonized part.

The central portion of the top 2 is formed of PVC from which the carbon black is absent, so that the PVC material is clear. This shows without shading in Fig. 2. It provides a transparent, non-sonductive window 32 through which integrated circuits in the packaging tube can be seen. The window 32 joins the top margins 31 through shoulders 33. These merge tangentially into the margins 31 but meet the flat window 32 at right angle corners. Accordingly the antistatic margins 31 stand proud, within the tube, from the internal surface of the window 32.

Therefore the encapsulated components in the tube cannot touch the window but are held in a position spaced from it. A further feature of this tube cross section is that the tubes will stack with the window 32 of one fitting into the area 9 (at the base of the projection 10) of another.

This packaging tube can be extruded from PVC with carbon black as the anti-static material, or it can be made from the conventional materials polystyrene or polypropylene as alternatives to PVC.

Figs. 3 to 1 3 show further possible cross sections. In each case anti-static material is shown shaded while window material is shown without shading. The anti-static material can in each case be rigid PVC incorporating carbon black.

The cross sections shown in Figs. 3, 4 and 8 to 10 are based on a trapezoidal shape similar to that of Figs. 1 and 2. The crosssections shown in Figs. 5 to 7 and 11 to 1 3 are based on a rectangular shape, i.e. both pairs of sides are parallel. In the case of Fig. 3 the top surface 2 is very narrow, and is entirely taken up by the window 32. Between the side walls 4, 6 and the top wall 2 there are angled walls 34.

The angled walls 34 prevent the body of the component from reaching the top wall 2 and the window 32.

Fig. 4 shows a cross-section in which the window 32 is in the plane of the top wall 2, but longitudinal inwardly directed ridges 36 either side of the window prevent the body of the component from reaching the window.

Fig. 5, 6 and 7 show cross-sections in which the basic shape is rectangular instead of trapezoid. The cross-section of Fig. 5 is analogous to that of Fig. 2 in that the window 32 is recessed and shoulders 33 prevent the body of the component from reaching the window. The embodiment shown in Fig. 6 has angled walls 34, analogous to those shown in Fig. 3. These prevent the component body 14 from reaching the top wall 2 without twisting. The top wall 2 is considerably wider than in the embodiment of Fig. 3, and if the component twists (shown in phantom on Fig. 6) its body 14 can touch the top wall 2. However, the window 32 is only in a central portion of the top wall 2, whereas the component body can only touch the margins 31 of the top wall 2. Therefore the component body is still prevented from touching the window. Fig. 7 is analogous to Fig. 4.

Figs. 8 to 1 3 show cross-sections of tubes which are analogous to Figs. 2 to 7 respectively, except that the tubes of Figs. 8 to 1 3 have a second window 32a in the internal projection 10. This second window 32a extends longitudinally along the end face of the projection 10, and is recessed so that it cannot come into contact with the body 14 of a component in the tube. The component body will be held away from the window 32a by the side margins 40 of the end face of the projection 10.

One advantage of the constructions of Figs.

8 to 1 3 is that the transparent PVC of the windows 32, 32a is stronger than the opaque conductive PVC of the rest of the tube. Consequently the second window 32a adds to the strength of the tube.

Figs. 14 to 1 6 show apparatus for forming tubes such as those of Figs. 2 to 7 having a single window.

A distinguishing feature of this apparatus is that it has two main screwsfor extruding plastics material. The screw 41 is for clear PVC, the screw 42 for opaque PVC incorporating carbon black as conductive antistatic material.

The two different plastics materials are advanced along respective tubes 43, 44 within which the screws 41, 42 operate. The tube 44 delivers directly into a prolongation of it 46 of the same diameter. Within this prolongation there is a central mandrel 48 supported on a web 50, while on the opposite side of the mandrel to this web there is a tube 52 which is connected to the tube 43 by a duct 54 as shown. The mandrel incorporates an air vent 56.

The downstream part of the mandrel 48 is surrounded by an extrusion die 58, held in place by a large forged nut 60. The die and mandrel together define an annular extrusion orifice. The die may be heated.

Molten opaque plastic is driven forward by the screw 42 from the tube 44 into the prolongation 46. Molten clear plastic is driven by the screw 41 through the duct 54 and out of the tube 52 to form a clear stream within the stream of opaque plastic. The streams of molten plastic merge without mixing and are extruded together through the orifice as a circular tube with a transparent sector 61 and a much larger opaque sector 62 as shown by Fig. 1 0. The size of the tube 52 and the feed rates of the two screws 41, 42 are arranged so as to give sectors 61, 62 of the desired size.

Figs. 1 7 to 1 9 show a variant form of the apparatus of Figs. 14 to 16. This variant form is suitable for forming tubes with two windows as shown in Figs. 8 to 1 3.

The variant form has a second tube 43a for clear plastics material, with a screw 41 a, a leading via a second duct 54a to a second tube 52a at the mandrel 48. Its structure and operation are as those of the apparatus of Figs. 14 to 16, except that since there are two tubes 52, 52a either side of the mandrel 48, the web 50 is displaced as shown in Fig.

1 8. The extruded tube of plastic obviously has two clear sectors 61, 61 a and two opaque sectors 62.

The circular tube 64 produced by the apparatus of Figs. 14 to 16 or 17 to 19 is then formed to the shape required by a die. Figs.

20 and 21 show the die 70 for the tube of Figs. 1 and 2. Dies for other tube crosssections would be analogous.

The tubular extrusion is fed into the die 70 while it is still hot enough to be soft, and within the die is formed to the tube shape 66.

The die 70 is cooled with water which passes through tubes 72. Preferably the water is supplied at a temperature of from 3" to 7"C.

A vacuum or partial vacuum is connected to tubes 74 to assist in forming the plastic tube shape 66. As shown by the cross-sectional view in Fig. 12, the subatmospheric pressure applied via tubes 74 is used to suck the tube against the sides and particularly the edges of the die 70. The tubes 74 are connected to the die cavity 75 by narrow passages 76 which enter the die cavity particularly at positions along the edges of the die cavity.

The die cavity 75 should of course have a shape appropriate to the tube being made.

The shape shown is that of the tube of Figs. 1 and 2.

For all of the tubes described above the antistatic PVC containing carbon black can for example be formed by compounding the following materials in the proportions by weight stated: PVC powder 67% carbon black 30% stabilizer 1.5% lubricant 0.5% processing aid 1 % The carbon black used must of course be conductive so that no static electricity can accumulate on the parts of the surface of the tube formed from it.

The thickness of the tube walls, preferably lies between 0.014 and 0.060 inches. (Wall and coating thicknesses are somewhat exaggerated in the drawings).

Claims

CLAIMS 1. A packaging tube for electronic components of predetermined form, the tube comprising opaque antistatic material and having at least one window of light transmitting material, providing along the length of the tube means for seeing electronic components in the tube, the shape and size of the tube correlative to said electronic components of predetermined form being such as to prevent contact between said components and said light transmitting material when said components are packaged inside the tube. 2. A packaging tube according to claim 1 having a window of light transmitting material extending continuously along the length of the tube. 3. A packaging tube according to Claim 1 or Claim 2 which is a hollow elongate tube of substantially quadrilateral overall cross-section with two opposed parallel sides, there being an indentation along the length of the tube in a first said parallel side to provide an internal projection to be straddled by electronic components in the tube, the said window(s) being provided in the second said parallel side. 4. A packaging tube according to claim 3 in which the said overall cross-section is trapezoid, the first said parallel side being longer than the said second. 5. A packaging tube according to claim 3 in which the said overall cross-section is rectangular. 6. A packaging tube according to any one of the preceding claims which has at least one additional window with which the material of the components of predetermined shape cannot come into contact, spaced around the cross section of the tube from the first window(s). 7. A packaging tube according to any one of claims 3 to 5 which additionally has at least one additional window with which the material of the components of predetermined shape cannot come into contact, the said additional window(s) being located in the face of said indentation nearest to the said second parallel side of the tube. 8. A packaging tube according to claims 6 to 7 wherein a said additional window extends continuously along the length of the tube. 9. A packaging tube according to any one of the preceding claims in which the or a said window is recessed from the inner surface of the tube. 10. A packaging tube according to any one of claims 1 to 8 in which the or a said window lies between two projections into the interior of the tube. 11. A packing tube according to Claim 2 or Claim 8, made by extrusion together of streams of light-transmitting thermoplastic material and opaque antistatic thermoplastic material. 1 2. A packaging tube according to any one of the preceding claims wherein said opaque antistatic material comprises polyvinylchloride incorporating carbon black. 1 3. A method of making a packaging tube according Claim 2 or Claim 8 comprising the steps of a) forming and advancing a stream of molten light-transmitting thermoplastic material by means of a first feed screw; b) forming and advancing a stream of molten opaque antistatic material by means of a second feed screw; c) feeding both said streams to respective separate portions of a tubular passage, which passage terminates in an extrusion ofifice; d) allowing said streams to merge in said passage and extruding them together through said orifice to form a hollow tube with a light transmitting window therein. 14. A method of making a packaging tube according to Claim 8 which comprises the steps of a) forming and advancing two streams of light transmitting thermoplastic material by means of respective feed screws, b) forming and advancing two streams of light transmitting thermopisastic material by means of respective feed screws, c) feeding all three said streams to respective separate portions of a tubular passage, which passage terminates in an extrusion orifice d) allowing the said streams to merge in the said passage and extruding them together through the orifice to form a hollow tube with two light transmitting windows therein. 1 5. A method according to Claims 1 3 or 14 in which the tube is subsequently shaped further while still soft. 1 6. A packaging tube substantially as herein described with reference to and as illustrated in any one of Figs. 1 to 1 3 of the accompanying drawings. CLAIMS (11 Oct 1983)

1. A packaging tube for electronic components of predetermined form, the tube comprising opaque antistatic material and having at least one window of light transmitting material, providing along the length of the tube means for seeing electronic components in the tube, the shape and size of the tube correlative to said electronic components of predetermined form being such as to prevent contact between said components and said light transmitting material when said components are packed inside the tube, and the shape of the tube including at least one projecting region, and at least one recessed region which engage so as to locate the tubes when one tube is stacked upon another.

2. A packaging tube according to claim 1 wherein the or at least one said window projects from the tube and is engagable with the or a said recessed region of a like tube.

3. A packaging tube according to claim 1 having a window of light transmitting material extending continuously along the length of the tube.

4. A packaging tube according to claim 3 wherein the window projects from the tube and is engagable with a said recessed region which also extends continuously along the length of the tube.

5. A packaging tube according to any one of the preceding claims which is a hollow elongate tube of substantially quadrilateral overall cross-section with two opposed parallel sides, there being an indentation along the length of the tube in a first said parallel side to provide an internal projection to be straddled by electronic components in the tube, the said window(s) and the said projecting region(s) being provided in the second said parallel side.

6. A packaging tube according to claim 5 wherein the said window(s) constitute the said projecting region(s).

7. A packaging tube according to claim 5 or claim 6 in which the said overall crosssection is trapezoid, the first said parallel side being longer than the said second.

8. A packaging tube according to claim 5 or claim 6 in which the said overall crosssection is rectangular.

9. A packaging tube according to any one of the preceding claims which has at least one additional window with which the material of the components of predetermined shape cannot come into contact, spaced around the cross section of the tube from the first window(s).

10. A packaging tube according to any one of claims 6 to 8 which additionally has at least one additional window with which the material of the components of predetermined shape cannot come into contact, the said additional window(s) being located in the face of said indentation nearest to the said second parallel side of the tube.

11. A packaging tube according to claim 9 or claim 10 wherein a said additional window extends continuously along the length of the tube.

1 2. A packaging tube according to any one of the preceding claims in which the or a said window is recessed from the inner surface of a wall of the tube, and stands proud of the outer surface of the same wall of the tube.

1 3. A packaging tube according to any one of claims 1 to 11 in which the or a said window lies between two projections into the interior of the tube.

14. A packaging tube for electronic components of predetermined form, the tube comprising opaque antistatic material and having at least one window of light transmitting material, providing along the length of the tube means for seeing electronic components in the tube, which window stands proud of the outer surface of a wall of the tube and is recessed from the inner surface of the same wall so as to prevent contact between said components and said light transmitting material when said components are packed inside the tube.

1 5. A packaging tube according to claim 14 which is a hollow elongate tube of substantially quadrilateral overall cross-section with two opposed parallel sides, there being an indentation along the length of the tube in a first said parallel side to provide an internal projection to be straddled by electronic components in the tube, the said window being a continuous window provided in the second said parallel side, recessed therefrom on the inside and standing proud thereof on the outside of the tube.

16. A packaging tube according to claim 1 5 in which the said overall cross-section is trapezoid, the first said parallel side being longer than the said second.

1 7. A packing tube according to claim 3, claim 11, claim 1 5 or any claim appendant thereto made by extrusion together of streams of light-transmitting thermoplastic material and opaque antistatic thermoplastic material.

1 8. A packaging tube according to any one of the preceding claims wherein said opaque antistatic material comprises polyvinylchloride incorporating carbon black.

1 9. A method of making a packaging tube according to claim 3, claim 11, claim 1 5 or any claim appendant thereto comprising the steps of a) forming and advancing a stream of molten light-transmitting thermoplastic material by means of a first feed screw; b) forming and advancing a stream of molten opaque antistatic material by means of a second feed screw; c) feeding both said streams to respective separate portions of a tubular passage, which passage terminates in an extrusion orifice; d) allowing said streams to merge in said passage and extruding them together through said orifice to form a hollow tube as specified in any of claims 3, 11, 1 5 or claims appendant thereto.

20. A method of making a packaging tube according to claim 11 which comprises the steps of a) forming and advancing two streams of light transmitting thermoplastic material by means of respective feed screws, b) forming and advancing two streams of light transmitting thermoplastic material by means of respective feed screws, c) feeding all three said streams to respective separate portions of a tubular passage, which passage terminates in an extrusion orifice, d) allowing the said streams to merge in the said passage and extruding them together through the orifice to form a hollow tube with two light transmitting windows therein, as specified in claim 11.

21. A method according to claim 20 or claim 21 in which the tube is subsequently shaped further while still soft.

22. A packaging tube substantially as herein described with reference to and as illustrated in any one of Figs. 1, 2, 5, 8, 11 of the accompanying drawings.