WO2007035374A1

WO2007035374A1 - Cover tape and method for manufacture

Info

Publication number: WO2007035374A1
Application number: PCT/US2006/035704
Authority: WO
Inventors: Ruben E. Velasquez Urey; Laura C. Devaney; David J. Vanoverbeke; Daniel H. Henderson; Barbara L. Birrell
Original assignee: 3M Innovative Properties Company
Priority date: 2005-09-16
Filing date: 2006-09-13
Publication date: 2007-03-29
Also published as: TW200726341A; KR20080052592A; CN101273677A; EP1932408A1; MY154939A; US20070062844A1; IL190163A0; JP2014015263A; TWI418270B; CN101273678A; CN101273677B; JP2009508773A

Abstract

An article includes a cover tape, which includes a base film layer, recessed areas, tear enabling features, and an adhesive. The base film layer has opposed longitudinal edges. The recessed areas extend along the longitudinal edges of the base film layer. The tear enabling features are substantially parallel to the longitudinal edges. The adhesive is disposed on the recessed areas.

Description

COVERTAPEAND METHOD FORMANUFACTURE

BACKGROUND

The present invention relates to tapes for carrying components and a method and apparatus for making such tapes. In manufacturing settings, it is often necessary to hold and transport components.

For example, in the field of electronics circuit assembly, electronic components are often carried from a supply of components to a specific location on a circuit board for attachment thereto. The components may be of several different types, including surface mount components. Particular examples include memory chips, integrated circuit chips, resistors, connectors, processors, capacitors, gate arrays, etc. It is possible to transport small and delicate components using a carrier tape/cover tape system, such as that disclosed in U.S. Pat. No. 5,325,654.

The electronic industry is continually moving towards smaller devices and thus smaller components, which in turn require more delicate and precise removal of such components from the carrier tape/cover tape system. Most known cover tapes use heat activated adhesive (HAA) or pressure sensitive adhesive (PSA) to bond the cover tape to the carrier tape. Removal of the components is done by first carefully peeling or debonding the cover tape off of the carrier tape to expose the component to vacuum nozzles or other component handling equipment for safe component removal. However, known cover tapes present several operational difficulties. For instance, peeling the cover tape from the carrier tape can create "shocky", rough, nonuniform and inconsistent peels, which cause movement of the carrier tape/cover tape that can displace the small components. Shocky peels have also been known to eject the small components out of the pocket in the carrier tape, thus causing miss-picks and eventual shut down of automated component handling equipment.

The peel force of adhesive cover tape can vary considerably depending on the width of the cover tape and the type of carrier tape used. Wider HAA cover tapes require higher heat to get secure bonds. Likewise, wider PSA cover tapes have lower peel forces and require wider adhesive exposure to get secure bonds. In addition, cover tapes that are designed for one type of carrier tape (e.g., polystyrene) do not always have good performance from other types of carrier material (e.g., polycarbonate). Even if cover tapes do nominally work with different types of carrier tapes, they may have less than optimum peel force and nonuniform peels. Moreover, HAA cover tapes also have poor stability as the peel force degrades with time and temperature.

Additionally, known cover tapes present difficulties in storing and transporting the cover tape. For instance, adhesive "squeeze-out" can occur when adhesives on a bottom surface of a tape migrate and deform under pressure and/or heat such that adhesive moves beyond the edges of the tape. This is problematic, as it can cause adhesives to adhere in undesired locations, lead to contamination, necessitate undesired cleaning, lessen aesthetic values, as well as present other problems such as undesired equipment downtime. Moreover, where a cover tape made of a flat film (i.e., a film without recesses) is wound upon itself, it can cause undesired sagging in between adhesive stripes, which leads to an unstable roll.

BRIEF SUMMARY

In one aspect of the present invention, an article includes a cover tape, which includes a base film layer, recessed areas, tear enabling features, and an adhesive. The base film layer has opposed longitudinal edges. The recessed areas extend along the longitudinal edges of the base film layer. The tear enabling features are substantially parallel to the longitudinal edges of the base film. The adhesive is disposed on the recessed areas. In another aspect of the present invention, a method of making a cover tape includes providing a base film layer having opposed longitudinal edges, forming a recessed area extending along each longitudinal edge, forming tear enabling features substantially parallel to the longitudinal edges, and applying an adhesive on each of the recessed areas. The above summary is not intended to describe each disclosed embodiment or every implementation of the present invention. The figures and the detailed description, which follow, more particularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view of a cover tape according to the present invention. FIG. 2 is a cross-sectional schematic view of another embodiment of a cover tape according to the present invention. FIG. 3 is a cross-sectional schematic view of another embodiment of a cover tape according to the present invention. FIG. 4A is a cross-sectional schematic view of another embodiment of a cover tape according to the present invention. FIG. 4B is a cross-sectional schematic view of another embodiment of a cover tape according to the present invention.

FIG. 5 is a cross-sectional schematic view of the cover tape of FIG. 1 after heat and pressure have been applied.

FIG. 6 is a cross-sectional schematic side view of a portion of a roll of cover tape according to the present invention. FIG. 7 is a perspective view of a carrier tape/cover tape system according to the present invention, showing separation of the cover tape therefrom. FIG. 8 is a schematic side view of a cover tape scoring apparatus according to the present invention. FIG. 9 is a cross-sectional schematic side view of a portion of the scoring apparatus of

FIG. 8.

FIG. 10 is a schematic back view of a portion of the scoring apparatus of FIGS. 8 and 9. FIG. 1 IA is a cross-sectional schematic view of an embodiment of a series of cover tapes according to the present invention. FIG. HB is a cross-sectional schematic view of another embodiment of a series of cover tape according to the present invention.

While the above-identified drawing figures set forth several embodiments of the invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale. Like reference numbers have been used throughout the figures to denote like parts.

DETAILED DESCRIPTION Aspects of the present invention relate to a cover tape, a carrier tape/cover tape system, as well as to a method and apparatus for making a cover tape. A cover tape according to the present invention can be adhered to a carrier tape, which can hold components for storage and transportation. The cover tape can cover pockets in the carrier tape that can hold components, and has a portion that can be separated from the system to expose the pockets in the carrier tape. Tear enabling features on the cover tape permit the portion of the cover tape to be separated from other portions of the cover tape (and a carrier tape to which the cover tape was adhered) with a substantially consistent and uniform separation force, which reduces the possibility of undesired movement of components held by the carrier tape during the separation process. As used herein, the term "tear" means generally controlled separation of portions of a component. In addition, the cover tape according to the present invention provides recesses along the longitudinal edges of the cover tape, which help the cover tape maintain a relatively flat profile during storage and application. The location of the adhesive is spaced from the edge of the cover tape, which helps prevent contamination of the adhesive and undesired adhesion of the adhesive to other surfaces, such as cover tape handling equipment.

FIG. 1 is a cross-sectional schematic view of a cover tape 20 suitable for use in a carrier tape/cover tape system. The cover tape 20 includes an elongate film 22 that has opposed longitudinal edges 24 and 26, and opposed top and bottom faces 28 and 30, respectively. The film 22 can be a polymer film, for example, polyethylene terephthalate, oriented polypropylene (e.g., biaxially oriented polypropylene), oriented polyamides, oriented polyvinyl chloride, polystyrene, polycarbonate, polyethylene, polyacrylonitrile, polyolefin and polyimide films. The film 22 can be transparent. Additionally, the film 22 can be intrinsically electrically conductive or static dissipative. Longitudinally extending tear enabling features 32 and 34 and longitudinally extending recesses 36 and 38 are located relative to the bottom face 30 of the film 22. The tear enabling features 32 and 34 are spaced apart, and a central portion 40 of the film 22 is defined therebetween. A top coating 42 is optionally provided along top face 28 of film 22. The top coating 42 can include a static dissipative (SD) coating, LAB (i.e., an adhesive release coating), an anti- reflective or glare-reducing coating, and other coatings and combinations of coatings. A bottom coating 44 is also optionally provided along the bottom face 30 of the film 22, which can be a SD coating or other type of coating and can be at least partially blended with the film 22. Longitudinally disposed adhesive stripes 46 and 48 are provided along the recesses 36 and 38.

The recesses 36 and 38 are located at the longitudinal edges 24 and 26, respectively, of the film 22. The recesses 36 and 38 are each open facing the bottom face 30 and longitudinal edges 24 and 26, respectively, of the film 22. Alternatively, recesses may be formed on both surfaces of the cover tape. This feature would be useful, for example, if the thicknesses of the adhesive stripes are greater than depth D_R, because it would facilitate winding of the cover tape.

In the embodiment shown in FIG. 1, a bottom portion 50 and a side portion 52 define each of the recesses 36 and 38. The adhesive stripes 46 and 48 can be disposed on the bottom portions 50 of the recesses 36 and 38, respectively. The bottom portions 50 of the recesses 36 and 38 can have microtexture (not shown in FIG. 1) for better adhering the adhesive stripes 46 and 48 to the film 22. It should be recognized that other recess shapes can be utilized, so long as the recesses 36 and 38 are open facing an adjacent elongate edge 24 or 26 of the film 22 and the bottom face 30 of the film 22.

The film 22, including recesses 36 and 38 and any microtextures, can be formed using processes such as scoring, extrusion, calendaring, micro-replication, laser ablation, ultrasound, die cutting, chemical etching, and stripping. In further embodiments, the recesses 36 and 38 can be formed using different processes. Moreover, the film 22 can be formed using a film that can fracture or delaminates along a centerline (i.e., a line halfway between the top and bottom faces 28 and 30 of the film 22), and separation lines can be cut from the top and bottom to the centerline in order to form the recesses. As illustrated in Fig. HA, the fracture or delamination centerline can be established, for example, by laminating or co-extruding two layers of different material 25, 27 that have a weak interface. Multiple cover tapes 20 can be formed from a single film web of the two layer material by cutting multiple separation lines across the width of the sheet. Separation lines in one layer will be a width Wo apart. These separation lines will form opposed longitudinal edges 24 and 26 of each adjacent cover tape 20. Separation lines in the second layer will be spaced away from the separation lines in the first layer by a width W_R. These separation lines will form side portions 52 of each adjacent cover tape, which side portions are a width Wi apart. The portion of the second layer opposite the separation line in the first layer will be scrap material 29. After the separation lines are cut, tapes 20 are formed by separating sections of film 22 along edges 24 and 26, side portion 52, and fracture line 31. Fracture line 31 forms the interior side of scrap material 29.

As shown in Fig. 1 IB, to avoid having this scrap material, a different process may be used. In this case, both the top and bottom layers of the film web are made of the same material 25 with a thin layer of a different material 27 between these layers to allow for fracture or delamination. Preferably, the cohesive strength of material 27 is less than the adhesive strength between materials 25 and 27. Because the top and bottom layer materials are the same, both layers may form the wider and narrower portion of the cover tape. (This method could also be used with the top and bottom layers being different materials, but is particularly useful when it is desirable to have the top and bottom layers made of the same material.) Accordingly, adjacent cover tapes may be arranged adjacent each other top-to-bottom (i.e., arranged at a 180° angle relative to each other). Therefore, each separation line in a layer will form a longitudinal edge 24 or 26 of one cover tape and will also form side portion 52 of an adjacent tape. In other words, separation lines on each of the layers will alternately be separated by a width of Wo and a width of Wi. In the relation of one layer to another, the distances between separation lines will alternate in opposite orders such that a width Wo in one layer 25 will be paired with a width Wi in the other layer 25. After the separation lines are cut, tapes 20 are formed by separating sections of film 22 along edges 24/52, 26/52 and fracture line 33. The adhesive stripes 46 and 48 on bottom portion 50 of recesses 36 and 38 can be, for instance, pressure sensitive adhesives (PSAs), heat activated and microencapsulated adhesives. The adhesive stripes 46 and 48 can have thicknesses greater than, less than or equal to a depth D_R of the recessed areas 36 and 38. Typically, the thickness is less than or equal to depth D_R. The adhesive stripes 46 and 48 have widths equal to or less than widths W_R of the recessed areas 36 and 38. Having widths less than widths D_R of recessed areas 36 and 38 provides substantially adhesive-free zones longitudinally extending along the bottom portions 50 of the recesses 36 and 38 on either side of each of the adhesive stripes 46 and 48 when the cover tape 20 is not applied to a surface (i.e., is not under tension). The tear enabling features 32 and 34 are located relative to the bottom face 30 of the film 22, and can be located adjacent the recesses 36 and 38 at the side portions 52 thereof. However, in further embodiments, the tear enabling features 32 and 34 can be located nearly anywhere along the top face 28, bottom face 3O₅ or both faces of the film 22, so long as they are each spaced from the longitudinal edges 24 and 26 of the film 22. As shown in FIG. 1, the tear enabling features 32 and 34 are continuous scoring lines that extend longitudinally along film 22. Such scoring lines can be formed by cutting into the film 22 (e.g., with lasers, die cutters, and blades, for instance, according to the blade scoring procedure described below). In further embodiments, the tear enabling features 32 and 34 can be weakened regions of the film 22 (e.g., thinner regions, microperforations, etc.), a transition between two materials (e.g., a first material comprises central portion 40 of the film 22 and a second material comprises the region of the film 22 between the bottom portions 50 of the recesses 36 and 38 and the top face 28), or other structures that facilitate tearing.

In one embodiment, provided by way of example and not limitation, the cover tape 20 can have the following dimensions. An overall width Wo of the film 22 (measured between elongate edges 24 and 26) is about 1 inch (2.54 cm). A thickness T of the film 22 is about 2 mil (0.0254 mm) (measured at the thickest portion of the central region 40 of the film 22). The recesses 36 and 38 each have a width W_R of about 0.0393701 inch (1 mm) and a depth D_R of about 0.5 mil (0.0127 mm). The tear enabling features 32 and 34 are score lines each having a depth of about 1.5 mil (0.0381 mm) (measured from the bottom face 30 of the film 22). It should be recognized that dimensions of the cover tape 20 can vary, as desired. For instance, a width of the central portion 40 of the film 22 can be selected such that it is at least as wide as the pockets of a carrier tape with which the cover tape 20 is used.

FIG. 2 is a cross-sectional schematic view of another embodiment of a cover tape 80 according to the present invention. The cover tape 80 shown in FIG. 2 is generally similar to the cover tape 20 shown and described with respect to FIG. 1. The cover tape 80 of FIG. 2 further includes coatings 82 and 84 on elongate edges 24 and 26, respectively of the film 22. The coatings 82 and 84 can be LAB coatings in order to reduce the possibility of adhesive becoming attached to the elongate edges 24 and 26, and therefore reduce the possibility of undesired stickiness, contamination, and other problems associated with exposed adhesives.

FIG. 3 is a cross-sectional schematic view of another embodiment of a cover tape 90 according to the present invention. The cover tape 90 shown in FIG. 3 is generally similar to the cover tape 20 shown and described with respect to FIG. 1. The cover tape 90 of FIG. 3 further includes outer recess coatings 92 and 94 and inner recess coatings 96 and 98. The outer recess coatings 92 and 94 are each located on the bottom portions 50 of the recesses 36 and 38, adjacent to the adhesive stripes 46 and 48 and toward the elongate edges 24 and 26 of the Film 22. The inner recess coatings 96 and 98 are each located on the bottom portions 50 of the recesses 36 and 38, adjacent to the adhesive stripes 46 and 48 and toward the side portions 52 of the recesses 36 and 38. Coatings 92, 94, 96 and 98 can be, for example, LAB coatings or other tack-free materials that can help prevent undesired contact with adhesives by more positively constraining the adhesive stripes 46 and 48 within the recesses 36 and 38.

FIG. 4A is a cross-sectional schematic view of a further embodiment of a cover tape 100. The cover tape 100 is generally similar to cover tape 20; however, the film 22 includes a first material 104 and a second material 106. With cover tape 100, the second material 106 is located at (i.e., above) the recesses 36 and 38 and extends from elongate edges 24 or 26 to material interfaces 108. The central portion 40 of the film 22 is defined between material interfaces 108.

The material interfaces 108 exhibit weaker bonding or connection strength than internal bonding or cohesion of either the first material 104 or the second material 106. The relative weakness of the material interfaces 108 facilitates substantially consistent and uniform tearing, that is, the separation of the first material 104 and the second material 106 at the material interfaces 108. Thus, the material interfaces 108 can form tear enabling features.

The first and second materials 104 and 106 can generally be selected from the same types of materials discussed with respect to FIGS. 1-3 above. In some embodiments the first material 104 can be weaker than the second material 106, or vice versa. In other words, one material can have weaker internal cohesive or bonding properties than the other. Moreover, the central portion 40 of the film 22 can be transparent and have high optical clarity.

The films 22 of cover tapes 100 can be fabricated using processes such as co- extrusion and profile extrusion. With co-extrusion, the first and second materials 104 and 106 are extruded together in a desired arrangement. With profile extrusion, the first and second materials 104 and 106 are extruded individually in desired shapes and are joined while still molten after the initial individual extrusion process. Fabrication may result is some negligible intermingling of the first and second materials 104 and 106 at their interface (e.g., at interface 108 in FIG. 4A). One advantage of this embodiment is that the tear enabling features do not require scoring. FIG. 4B is a cross-sectional schematic view of another embodiment of a cover tape

102. The cover tape 102 is generally similar to cover tape 100, and the film 22 includes a first material 104 and a second material 106. With cover tape 102, the second material 106 is disposed in elongate bands 110 and 112 positioned near side portions 52 of the recesses 36 and 38, with the first material 104 disposed on either side of bands 110 and 112 of the second material 106. The central portion 40 of the film 22 is defined between the bands 110 and 112 of the second material 106.

The second material 106 is generally weaker than the first material 104. In other words, the second material 106 has weaker internal cohesive or bonding properties than does the first material 104. This facilitates consistent and uniform tearing of the film 22 within the bands 110 and 112 of the second material 106. The bands 110 and 112 thus constitute tear enabling features. In some embodiments, the first material 104 can resist tearing. The second material 106 can comprise a different and weaker form of the type of material as the first material 104, or can be an entirely different type of material. The first and second materials can generally be selected from the same types of materials discussed with respect to FIGS. 1-3 above. In addition, the weaker second material 106 can be made of ethylene vinyl acetate (EVA). One advantage of this embodiment is that the tear enabling features do not require scoring.

FIG. 5 is a cross-sectional schematic view of the cover tape 20 of FIG. 1 after heat and pressure have been applied. In use, the cover tape 20 may be placed in contact with a surface (e.g., wound upon itself) such that tensile and compressive forces act on the tape 20. Heat and pressure can cause portions of the film 22 near the recesses 36 and 38 to deflect slightly. Heat and pressure can also cause the adhesive stripes 46 and 48 to deform and migrate. More particularly, heat and pressure can cause the adhesive stripes 46 and 48 to change from first shapes 46A and 48 A to second shapes 46B and 48B. First shapes 46A and 48A have a generally greater thickness and generally lesser width than second shapes 46B and 48B. Nonetheless, even after such deformation, the adhesive stripes 46 and 48 are substantially contained within recesses 36 and 38 despite the presence of pressure and heat. In the second shapes 46B and 48B, the adhesive stripes 46 and 48 are generally spaced from side walls 52 of recesses 36 and 38, and spaced from the elongate edges 24 and 26 of the film 22. By substantially containing the adhesive stripes 46 and 48 within the recesses 36 and 38 (even when deformed by heat and/or pressure), the cover tape 20 can be securely adhered to a desired location without undesired exposure of adhesive or adhesion in undesired locations. It should be noted that the features of the recesses 36 and 38 are not limited to the particular embodiment of cover tape shown in FIG. 5.

It is possible to place cover tape according to the present invention in the form of a roll. FIG. 6 is a cross-sectional schematic side view of a portion of a roll 120 of cover tape 20. The cover tape 20 is wound upon itself on a core 122 (e.g., a substantially cylindrical cardboard core). In this configuration, the top face 28 of the cover tape 20 is substantially smooth and flat, and the roll 120 is generally stable. In addition, sides 124 of the roll 120 are generally tack-free, as adhesive generally does not protrude from the cover tape 20 along the sides 124 of the roll 120 (adhesive is spaced from the side edges of the tape within the recesses). The adhesive stripes 46 and 48 can releasably adhere to the top coating 42 of the cover tape 20.

Cover tape can be placed in a roll (e.g., the roll 120 of FIG. 6) after it has been fabricated and prior to being adhered to a carrier tape. Placing the cover tape in a roll facilitates storage and transportation, as well as automated handling of the cover tape. Coating materials on the top face of the cover tape can facilitate peeling portions of the cover tape away from the roll.

Cover tape can be used in a carrier tape/cover tape system. FIG. 7 is a perspective view of a carrier tape/cover tape system 130 that includes a carrier tape 132 and cover tape 20. The carrier tape 132 has a pair of opposed elongate lip portions 134, and one or more pockets 136. Components 138, such as electronic components, can be placed in the pockets 136. After the components 138 have been placed in the pockets 136 of carrier tape 132, as desired, cover tape 20 can be adhered to elongate lip portions 134 in order to cover the pockets 136 and contain the components 138 between the carrier tape 132 and the cover tape 20. The cover tape 20 can be dispensed from a roll.

In order to expose and remove the components 138, a portion of the cover tape 20 is separated from the system 130. As shown in FIG. 7, the central portion 40 of the cover tape 20, defined between tear enabling features 32 and 34, is torn away. Outer portions 140 of cover tape 20 remain adhered to carrier tape 132 after the central portion 40 of the cover tape 20 is torn away. After being torn away, the central portion 40 of the cover tape 20 can be wound into a roll 142 for discard or recycling. The central portion 40 of the cover tape 20 is separated at the tear enabling features

32 and 34 (e.g., score lines in the embodiments shown and described with respect to FIGS. 1-3). In other embodiments, separation can occur at material interfaces (e.g., material interfaces 108 as shown and described with respect to FIG. 4A), at bands of weaker material (e.g., bands 110 and 112 of the second material 106 as shown and described with respect to FIG. 4B), or other locations depending on the type and location of tear enabling features.

It is desirable to have a substantially uniform tear force when tearing away a portion of the cover tape. Although lasers or blades can be used to create scoring lines, making multiple precise scoring lines capable of less than 0.001 inch (0.0254 mm) in variation can be expensive with lasers, and is nearly impossible with known uses of blades that are hindered by variations in blade cutting edge alignment.

In order to achieve uniform tearing with cover tapes having scoring lines, it is desired to provide scoring lines with very little variation in depth along the length of the cover tape as well as between distinct scoring lines. Scoring lines with substantially uniform depth can be simply and efficiently formed in a film web using the method and apparatus described below. Scoring lines are generally formed in a film web after the film has been formed with recesses; however, scoring lines can be performed at other stages of a cover tape fabrication process. For example, one possible manufacturing process includes forming a plurality of parallel, laterally spaced apart and longitudinally extending recesses in a large film web. Next, longitudinal scoring lines are formed in the large film web. Then longitudinal adhesive stripes are applied to the recesses of the film (e.g., two spaced apart stripes of adhesive, with one stripe within each recess). Finally, the large film web is cut and separated into a plurality of individual cover tape strips by cutting through each recess between the adhesive bands therein. FIG. 8 is a schematic side view of a scoring apparatus 200 that includes web support rollers 202A, 202B and 202C and a blade assembly 204. FIG. 9 is a cross- sectional schematic side view of the blade assembly 204. The blade assembly 204 includes a main structure 206 with a cavity 208 defined along a rear face 210 and a generally-U-shaped opening 212 defined along a front face 214. The main structure 206 is supported by a pivot 216. Alignment means 218 (e.g., adjustable micrometer assemblies) are provided in order to provide precise alignment of the scoring apparatus 200 relative to roller 202B, for instance, to adjust the scoring depth. In order to maintain a substantially constant scoring depth, it is preferable to reduce the impact of variability in geometry of support roller 202B. This can be achieved by attaching one or more scoring depth control rollers 228 to the main structure 206. These scoring depth control rollers 228 are in direct contact with the web support roller 202B and enable the main structure 206 to follow the contour of the web support roller 202B, which will minimize variations in scoring depth. One or more blades 220 (e.g., conventional flat metallic blades having linear tapered cutting edges in configurations generally resembling that of a single-edged razor blade) are inserted into cavity 208 such that cutting edges 222 of the blades 220 face the front face 214 of the main structure 206 and contact a precision inner surface 224 (FIG. 9) of the cavity 208 that defines a plane. The blades 220 are biased against the precision surface 224, using biasing means such as ties, springs and bumpers (biasing means not shown in FIG. 8). Generally central portions of the cutting edges 222 of the blades 220 are exposed through the opening 212 in order to permit the blades 220 to cut a film web material that contacts them. The main structure 206 of the blade assembly 204 can be formed of any material

(e.g., metal, glass, polymers, etc.) such that the precision inner surface 224 resists cutting by the blades 220. In one embodiment, the main structure 206 is formed of a metallic material that is at least as hard as the blades 220.

In operation, an unscored film 22A passes between the roller 202B and the blade assembly 204. The cutting edges 222 of the blades 220 are adjusted with alignment means 218 relative to the roller 202B, such that desired cutting depths are achieved. It is possible to provide different cutting depths for different blades. For instance, some blades can provide scoring while other blades can simultaneously cut apart individual cover tape strips from an article that includes a plurality of connected cover tape strips. However, cutting to separate individual cover tape strips need not be performed at the same time as scoring. After passing the blade assembly 204, the now scored film 22B can be moved by the roller 202C to other locations for further processing, and can be ultimately wound in a roll (e.g., roll 120 as shown and described with respect to FIG. 6).

It is possible to provide a plurality of score lines in a film simultaneously using the apparatus shown and described with respect to FIGS. 8 and 9. FIG. 10 is a schematic back view of the blade assembly 204. In FIG. 10, the blades have been omitted for clarity. A number of lateral spacers 226 are inserted into the cavity 208 of the blade assembly 204. Gaps are formed between adjacent spacers such that a blade can be inserted into the gap. The spacers provide for alignment of the blades across a width of a film to be scored. In addition, the spacers provide support to the blades, which can be thin, in order to increase rigidity of the blades and promote the formation of straight and uniform scoring lines. The number, size, and arrangement of the spacers 226 will vary according to the desired scoring pattern. The spacers 226 can be formed of a metallic or polymer material.

In further embodiments, the spacers 226 can be integrally formed with the main structure 206 of the blade assembly 204. In such embodiments, a blade alignment plane can be collectively defined by the plurality of precision surfaces 224 formed relative to each gap.

In light of the discussion above, numerous advantages and benefits of the present invention should be recognized. One advantage of the cover tape according to the present invention is that it has a very uniform removal force of the central portion of the tape, which reduces the risk of miss-picks during storage and transportation operation due to parts or components "jumping" out of the carrier pocket of the carrier tape. In addition, the cover tape can be made more cost effective by using adhesive stripes while resolving the winding issues normally encountered with adhesive stripe-coated tapes (e.g., unstable rolls with sagging problems). In addition, the cover tape of the present invention also reduces a risk of adhesive build-up on equipment due to adhesive "squeeze-out" by keeping the adhesive substantially contained in the recesses before and after tearing of the middle portion of the tape. It also has substantially tack-free side edges when wound in a roll format, which reduces a risk of contamination when the roll of cover tape is laid on a table or other surface. Further, while forming the cover tape, no cutting through adhesive is required, which may lead to more effective processing by avoiding adhesive build-up on cutting equipment. The method and apparatus for scoring the film also present numerous advantages. Scoring can be accomplished, simply, efficiently, and in a cost-effective manner. The scoring apparatus of the present invention permits substantially uniforms scoring depth to be provided, with relatively little variation in scoring depth. By using conventional blades (e.g., blades resembling single-edged razor blades) in the manner of the present invention, the scoring apparatus is relatively simple, and the blades and apparatus are relatively inexpensive. Moreover, by aligning the blades directly at their respective cutting edges, rather than using blade reference features (e.g., notches and holes) that are spaced from the cutting edges, undesired variation in cutting or scoring depth due to individual variations in the blades can be reduced.

Although the present invention has been described with reference to several alternative embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For instance, various types of tear enabling features can be used according to the present invention, and those tear enabling features can have various arrangements.

Claims

CLAIMS:

1. An article comprising: a cover tape comprising: a base film layer having opposed longitudinal edges; recessed areas extending along the longitudinal edges; tear enabling features substantially parallel to the longitudinal edges; and an adhesive on the recessed areas.

2. The article of claim 1, wherein the base film layer is composed of a material selected from the group consisting of polyethylene terephthalate, polypropylene, polyamides, polyvinyl chloride, polystyrene, polycarbonate, polyethylene, polyacrylonitrile, polyolefin and polyimide.

3. The article of claim 1, wherein the base film layer is composed of an oriented film.

4. The article of claim 1, wherein the base film layer is transparent.

5. The article of claim I₅ wherein the adhesive is selected from the group consisting of pressure sensitive, heat activated and microencapsulated adhesives.

6. The article of claim 1 wherein the article is wound upon itself, and wherein prior to being wound the adhesive has a thickness less than or equal to a depth of the recessed areas.

7. The article of claim 1 wherein the article is wound upon itself, and wherein prior to being wound the adhesive has an initial thickness greater than a depth of the recessed areas, and wherein the adhesive can be displaced after being wound such that the article has a substantially flat profile.

8. The article of claim 1 , wherein the adhesive has a width equal to or less than a width of the recessed areas.

9. The article of claim 1, wherein the adhesive in each recess is spaced from the longitudinal edge of the base film layer.

10. The article of claim 1, wherein the adhesive in each recess is spaced from an adjacent tear enabling feature.

11. The article of claim 1 , further comprising a tack-free material on the recessed area.

12. The article of claim 1, wherein two tear enabling features are provided, and each tear enabling feature is continuous.

13. The article of claim 1, wherein each tear enabling feature comprises a weaker zone in the base film layer.

14. The article of claim 1 , wherein the base film layer comprises a first material and a second material, and the tear enabling features comprise a transition between the first material and the second material.

15. The article of claim 1, wherein the tear enabling features provide a substantially consistent tear force.

16. The article of claim 1 and further comprising: a carrier tape having compartments formed therein for holding components, wherein the cover tape can be adhered to the carrier tape for sealing components in the compartments.

17. The article of claim 1, wherein each recessed area is open along an adjacent longitudinal edge of the base film layer.

18. A method of making a cover tape, the method comprising: providing a base film layer having opposed longitudinal edges; forming a recessed area in the base film layer extending along each longitudinal edge; forming tear enabling features in the base film layer substantially parallel to the longitudinal edges; and applying an adhesive on each of the recessed areas.

19. The method of claim 18, wherein the step of forming a recessed area comprises a process selected from the group consisting of scoring, extrusion, calendaring, micro- replication, laser ablation, ultrasound, chemical etching and stripping.

20. The method of claim 18 wherein the base film layer comprises two layers of laminated or coextruded materials that have a weak interface, and wherein the step of forming a recessed area comprises cutting each layer to the interface at offset locations, then separating sections of the two-layer base film layer from each other along the cuts and a portion of the interface.

21. The method of claim 18 wherein the base film layer comprises two outer layers of laminated or coextruded materials separated by a intermediate layer of material having a weaker cohesive force than adhesive force with the outer materials, and wherein the step of forming a recessed area comprises cutting each outer layer to the interface with the intermediate layer at offset locations, then separating sections of the three-layer base film layer from each other along the cuts and a portion of the intermediate layer.

22. The method of claim 18, wherein the step of forming tear enabling features comprises a process selected from the group consisting of scoring, extrusion, calendaring, micro- replication, laser ablation, ultrasound, die cutting, and chemical etching.

23. The method of claim 18, wherein the base film layer comprises a first longitudinal strip of a film substrate having a plurality of such longitudinal side-by-side strips, and wherein the steps of claim 18 are performed in parallel to define a plurality of side-by- side cover tapes, and further comprising: separating adjacent cover tapes.