BACKGROUND
Carrier tapes are often used for transporting electronic components between manufacturing sites and customer sites. Prior art carrier tapes typically comprise a continuous web of plastic material that has pockets formed at regular intervals along the length of the web. Electronic components are placed in the pockets at a loading station. The loaded pockets are covered with strips of cover tape to maintain the electronic components in the pockets. The loaded carrier tape is typically mounted on a reel for transport to a customer site. At the customer site the loaded carrier tape is unwound from the reel. The cover tape is stripped off each pocket and the electronic component is unloaded from the pocket.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a carrier tape having electronic components mounted in pocket structures thereof.
FIG. 2 is a cross sectional view of the carrier tape of FIG. 1.
FIG. 3 is another cross sectional view of the carrier tape of FIG. 1.
FIG. 4 is a partially schematic top plan view of the carrier tape of FIG. 1, illustrating placement of an electronic component into a pocket structure.
FIG. 5 is a cross sectional elevation view of the carrier tape of FIG. 4.
FIG. 6 is partially schematic view of another cross sectional portion of the carrier tape of FIG. 4, illustrating placement of an electronic component into a pocket structure.
FIG. 7 is a partially schematic top plan view of the carrier tape of FIG. 1, illustrating removal of an electronic component from a pocket structure thereof.
FIG. 8 is a partially schematic cross sectional view of the carrier tape of FIG. 7.
FIG. 9 is a top plan view of drive chain portions of a carrier tape displacement assembly.
FIG. 10 is a cross sectional view of a portion of windings of a prior art carrier tape mounted on a reel.
FIG. 11 is a cross sectional view of a portion of winding of the carrier tape of FIGS. 1-8 mounted on a reel.
DETAILED DESCRIPTION
This specification, in general, discloses a carrier tape 10 that may be used for transporting electronic components 80. As shown by FIGS. 1 and 2, the carrier tape 10 may comprise a continuous web 12. A plurality of pocket structures 24 are connected to the continuous web 12 and are adapted to receive at least one of the electronic components 80. Each of the plurality of pocket structures 24 defines an opening 25 adapted to enable passage of at least one of the electronic components 80 into the pocket structure 24. Each of the plurality of pocket structures 24 defines at least one tab, e.g., 51, which is adapted to retain the electronic component 80 in the pocket structure 24 without a separate closure member, such as a PSA cover tape used with conventional carrier tape. Having thus generally described one embodiment of a carrier tape, this carrier tape embodiment will now be described in further detail as well as a packaging system and a packaging assembly that include carrier tape.
As illustrated in FIG. 1, a carrier tape 10 may comprise a continuous web 12 having a first edge portion 14 and an opposite second edge portion 16, which extend between a top surface 18 and a bottom surface 22. As best illustrated in FIGS. 1-3, a pocket structure 24, which may be integrally formed with the continuous web 12, extends downwardly from the bottom surface 22 of the continuous web 12. The pocket structure has a top opening 25 over which the continuous web does not extend. Pocket structures 24 in one embodiment, as best illustrated in FIGS. 2 and 3, may have a generally trapezoidal lateral cross section and may include a rectangular bottom wall 26 extending generally parallel to the continuous web 12. The pocket structures also include a plurality of lateral side walls 28 and end walls 32, FIGS. 2 and 3 that extend transversely to the bottom wall 26. The lateral side walls 28 and end walls 32 may be integrally connected to the continuous web 12. Each pocket structure 24 has an inner surface 36 and an outer surface 38. A connecting opening 40 is provided between adjacent pocket structures 24 as illustrated in FIGS. 1 and 3.
A first linear array of sprocket holes 42 is positioned parallel and adjacent to the first edge portion 14 and a second linear array of sprocket holes 44 is positioned adjacent and parallel to the second edge portion 16 of the web 12.
At least one tab 51 is associated with each pocket structure 24 and extends out over the opening 25 in the pocket structure 24. In the embodiment illustrated in FIG. 1, a first aligned set of tabs 51, 53, 55, 57 is provided along one side of each opening 25 and a second aligned set of tabs 52, 54, 56, 58 is provided along the opposite side of the opening 25. Each tab 51, etc., may be a cantilever structure with a free or distal end 62, FIG. 2, and an attached or proximal end 64 connected to the web 12. In one embodiment, a notch 66 is provided at the free end 62 of each tab 51, etc. The notch 66 may have a first surface 68 extending generally parallel to the continuous web 12 and a second surface 69 extending transversely to the first surface 68. The surfaces 68, 69 may be adapted to engage surfaces of an electronic component 80 positioned within the pocket structure 24.
The web 12, pocket structures 24 and tabs 51, etc. may all be constructed from a resilient material such as, for example, Polystyrene (PS) or Polycarbonate (PC). A typical thickness of the web 12 is about 0.250 mm, a typical thickness range of the pocket structure 24 material is about 0.200 mm to 0.300 mm, a typical thickness range of the tab 51 material is about 0.250 mm to 0.300 mm. It will be understood that the indicated materials and dimensions are only examples and that the carrier tape 10 may be constructed from many different materials and may be made in many different sizes.
The electronic component 80 may have a bottom surface 82 that is engaged with the bottom wall 26 of the pocket. The electronic component 80 may have a top surface 84 and a plurality of lateral side surfaces 86. In one embodiment, the first and second surfaces 68, 69 of the notch 62 engage the top 84 and one lateral side surface 86 of the electronic component 80. Various electronic components 80 such as, for example, integrated circuit dies and other surface mount components may be loaded into the pocket structures 24. Although a single component 80 is shown loaded in each pocket structure 24 in the illustrated embodiments it will be understood that in some embodiments multiple components may be positioned in each pocket structure 24.
The loading of the carrier tape 10 with electronic components 80 is best illustrated in FIGS. 1-6 and 9. The carrier tape 10 is moved in an indexing direction 70 by a displacement assembly 150 such as a dual set of continuous drive belts or chains 110, 112, FIG. 9, which may be driven by a conventional drive motor provided with a conventional control system (not shown). The first continuous drive chain 110 may comprise a plurality of sprockets or studs 112, 114, 116, 118, 120, 122, etc. The second drive chain 130 may comprise a second set of sprockets or studs 132, 134, 136, 138, 140, 142, etc. The drive chains 110, 130 are driven at the same speed such that oppositely positioned studs, e.g., 112, 132 remain oppositely positioned along the entire path of the displacement assembly 150. The tape displacement assembly 150 may have an upstream end 152 and a downstream end 154. Between the upstream ends and the downstream ends 152, 154, there may be a first station 162 at which oppositely positioned studs, e.g., 112, 132 are positioned at a relatively close distance “a,” which in one embodiment in which the width of the carrier tape 10 is 32 mm, may be about 28.4 mm. The dimension “a” will of course vary with the width of the particular tape that is being used. Downstream from this first station 162 is a second station 164 at which oppositely positioned studs, e.g., 116, 136 are spaced apart at a second distance “b”. In one typical embodiment in which the tape 10 has a width of about 32 mm, the distance “b” may be about 31.8 mm. As further illustrated in FIG. 9, at a third station 166 positioned downstream from station 164, the spacing between opposite studs, e.g., 120, 140 may again be the relatively closely spaced distance “a”.
The sprocket holes 42, 44 in the continuous web 12 are adapted to receive studs 112, 114, etc., and 132, 134, etc., for displacing the web 12 in direction 70 as illustrated in FIGS. 1, 4, 7 and 9. In FIG. 1, all of the pocket structures 24 are positioned in the “normal” or “closed” position, i.e., the studs positioned within the sprocket holes 42, 44 in FIG. 1 are all positioned at a closed mode distance “a.” When the carrier tape 10 is transported, for example, between a packaging site and a customer site, all of the pocket structures 24 of the carrier tape 10 are in this “closed mode” and electronic components 80 are mounted in each pocket structure 24, The carrier tape 10, prior to leaving a packaging site, is typically wound about a conventional reel (not shown).
FIGS. 4-6 schematically illustrate the loading of electronic components 80 into pocket structures 24, which typically occurs at a packaging facility. At such a facility, the carrier tape 10 may be mounted on a carrier tape displacement assembly 150 as illustrated in FIG. 9. The carrier tape 10 is laterally, elastically stretched during its displacement from station 162 to station 164 (only station 164 is shown in FIG. 4). During this elastically deforming displacement, as best illustrated by FIG. 6, the pocket structure opening 25 becomes wider. For example, in one typical embodiment using carrier tape 10 having a width of 30 mm, the pocket opening 25 may increase from about 24.4 mm to about 27.8 mm (and the spacing between corresponding opposite tabs, e.g., 55, 56 may increase, e.g., from about 23.5 mm to about 26.9 mm) in a pocket structure 24 adapted to receive an electronic component 80 having a lateral dimension of about 23.9 mm. A conventional pick and place machine having a vacuum or other type of placement head 190 is positioned at station 164 and engages each electronic components 80, moves it into alignment with the opening 25 in a pocket structure 24 located at station 164, and lowers the electronic component 80 into the pocket structure 24, as best shown in FIG. 6. Once the electronic component 80 is placed in the pocket structure 24, the suction in the placement head 190 is released and the placement head 190 is raised, leaving the electronic component 80 in the pocket 24. As the placement assembly moves a pocket structure 24 of the carrier tape 10 from station 164 to station 166, the sprockets associated with the pocket 24 gradually comes closer until the pocket 24 reaches the closed mode station 166. At station 166 the studs in sprocket holes 42, 44 are again spaced at distance “a” and the tabs, e.g., 55, 56 move into the closed mode position illustrated in FIG. 2 in which the electronic component 80 is engaged by the tabs, e.g., 55, 56. The tabs 55, 56 may be configured so as to exert downward pressure on the component 80, urging it against the bottom wall 26 and thus stably holding it within the pocket structure 24.
An unloading operation, which typically takes place at a customer site, is illustrated with reference to FIGS. 7, 8 and 9. The carrier tape 10 is moved along a path such as illustrated in FIG. 9 in which it passes from station 162, at which the opposite sprocket holes 42, 44 are positioned at the relatively close distance “a,” to station 164, at which the sprocket holes 42, 44 are positioned at the relatively widely spaced distance “b”. A pick and place machine having a pick-up head 192 is positioned at station 164. The distance between tabs, e.g., 53, 54 is now at the relatively widely spaced distance “b” enabling the pick-up head 192 to descend into the pocket structure 24, engage the electronic component 80, lift the electronic component 80 out of the pocket, and then move it to an appropriate station for subsequent displacement, assembly, etc.
The new carrier tape 10 described herein may have a number of advantages over conventional carrier tape. One advantage is that no cover tape is required to cover the opening in each pocket structure 24. By eliminating the cover tape used in the prior art, certain problems of the prior art are also eliminated. For example, cover tape has a tendency to stick to the top of an electronic component placed within carrier tape pocket structures, often causing the electronic component to be “tossed,” i.e., removed from the pocket and discarded with the stripped off cover tape. Another advantage of the new carrier tape is that the tab structure described herein prevents “nesting” when the carrier tape is wound on a reel. In the prior art, as illustrated in FIG. 10, uncovered pocket structures 222 in successive windings 210, 212, 214 about a reel tend to nest in regions 225 in which the pocket structures 222 are randomly aligned. Such nesting leads to difficulties in initially unwinding the prior art carrier tape 200 and may also cause tearing or deforming stress to the tape 200. Also, in conventional carrier tape that relies on cover tape to close a pocket structure, there is usually a small gap between the top surface of a component and the cover tape. In this situation, the bottom of a pocket structure of the conventional carrier tape may nominally nest with an aligned pocket structure that is covered with cover tape. Such an occurrence may place high stress on the top of a component in the aligned pocket structure during a reel winding process. Thus the component in the pocket structure of the conventional carrier tape may be damaged. This problem is obviated by applicants' tab configuration that resists stress from an aligned pocket structure.
The absence of such prior art type nesting problems with applicants' carrier tape 10 may be seen in FIG. 11. Pocket structures 24 of various windings 182, 184, 186, 188 about a reel 180 may be aligned and yet do not nest because of the interference provided by the tabs 51, 53, etc.
Although certain embodiments of a new carrier tape and methods and assemblies for use thereof have been expressly described in detail herein, alternative embodiments of carrier tapes that employ the inventive concepts described herein will occur to those skilled in the art after reading this disclosure. It is intended that the appended claims be construed broadly to cover all such alternative embodiments except as limited by the prior art.
Patent Application
20150053586
