U.S. patent application number 13/662800 was filed with the patent office on 2013-02-28 for carrier tapes having tear-initiated cover tapes and methods of making thereof.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. The applicant listed for this patent is 3M Innovative Properties Company. Invention is credited to Rocky D. Edwards, Douglas B. Gundel, Ruben E. Velasquez Urey.
Application Number | 20130048220 13/662800 |
Document ID | / |
Family ID | 39082343 |
Filed Date | 2013-02-28 |
United States Patent
Application |
20130048220 |
Kind Code |
A1 |
Velasquez Urey; Ruben E. ;
et al. |
February 28, 2013 |
Carrier Tapes Having Tear-Initiated Cover Tapes and Methods of
Making Thereof
Abstract
A cover tape for use with a carrier tape, where the cover tape
includes at least one tear-initiation feature that defines a
predetermined direction of tear to initiate a tear along portions
of the cover tape.
Inventors: |
Velasquez Urey; Ruben E.;
(Austin, TX) ; Edwards; Rocky D.; (Lago Vista,
TX) ; Gundel; Douglas B.; (Cedar Park, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M Innovative Properties Company; |
St. Paul |
MN |
US |
|
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
ST. PAUL
MN
|
Family ID: |
39082343 |
Appl. No.: |
13/662800 |
Filed: |
October 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12368457 |
Feb 10, 2009 |
8323442 |
|
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13662800 |
|
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|
11835211 |
Aug 7, 2007 |
|
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12368457 |
|
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|
60821944 |
Aug 9, 2006 |
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Current U.S.
Class: |
156/701 |
Current CPC
Class: |
C09J 2301/204 20200801;
Y10T 156/1067 20150115; Y10T 156/1056 20150115; C09J 2301/18
20200801; Y10T 156/11 20150115; Y10T 428/15 20150115; Y10T 156/10
20150115; H05K 13/0084 20130101; C09J 7/22 20180101 |
Class at
Publication: |
156/701 |
International
Class: |
B32B 38/10 20060101
B32B038/10 |
Claims
1. A method of using a carrier tape, the method comprising:
providing the carrier tape having a cover tape bonded to a base
portion, wherein the cover tape includes a tear-initiation feature
and a score line; peeling a first portion of the cover tape from
the base portion until the peel reaches the tear-initiation
feature; peeling a second portion of the cover tape along the
tear-initiation feature; tearing a third portion of the cover tape
in a direction that substantially follows the tear-initiation
feature until the tear reaches the score line; and tearing a fourth
portion of the cover tape in a direction that substantially follows
the score line.
2. The method of claim 1, wherein the tear-initiation feature has
an arcuate shape.
3. The method of claim 1, wherein the cover tape comprises a
plurality of tear-initiation features.
4. The method of claim 1, wherein the tear-initiation feature does
not intersect the score line.
5. The method of claim 1, wherein at least a portion of the
tear-initiation feature has a linear shape.
6. The method of claim 1, wherein the tear-initiation feature is
cut prior to applying adhesive materials that bond the cover tape
to the base portion.
Description
REFERENCE TO CROSS-RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/368,457, filed Feb. 10, 2009, which is a divisional of U.S.
application Ser. No. 11/835,211, filed Aug. 7, 2007, which claims
priority to U.S. Provisional Patent Application 60/821,944, filed
Aug. 9, 2006, the disclosure of which is incorporated by reference
in its entirety herein.
BACKGROUND
[0002] The present invention relates to carrier tapes for storing
electronic surface mount components. In particular, the present
invention relates to carrier tapes that incorporate cover tapes
having tear-initiation features.
[0003] During electronic circuit assembly, electronic components
are often carried from a supply of such components to a specific
location on a circuit board for attachment. One way to provide a
continuous supply of electronic components to a desired location is
to load a series of such components into pockets that are spaced
along a carrier tape. The loaded carrier tape, which is usually
provided in roll form, may then be advanced toward a pick-up
location at a predetermined rate as each succeeding component is
removed from the tape by a robotic placement machine.
[0004] Conventional carrier tapes typically include a
self-supporting base portion that carries the component, and a
flexible cover tape that aids in preventing foreign matter from
deleteriously affecting the component. The cover tape is typically
sealed to the base portion with a sealing apparatus, and is
progressively peeled away from the base portion just before the
robotic placement machine removes the component from the carrier
tape. However, a common issue with carrier tapes is that the bond
between the base portion and the cover tape needs to be sufficient
to prevent the cover tape from prematurely delaminating from the
base portion, while also being weak enough to allow the cover tape
to be readily peeled off from the base portion without requiring
excessive removal forces or generating undesirable vibrations. As
such, there is a need for cover tapes that exhibit suitable bond
strengths to base portions and are also easy to remove when
desired.
BRIEF SUMMARY
[0005] At least one aspect of the present invention relates to a
cover tape for use with a carrier tape. The cover tape includes at
least one tear-initiation feature extending through a lateral edge
of the cover tape, where the tear-initiation feature at least
partially defines a predetermined direction of tear to initiate a
tear along portions of the cover tape. In one embodiment, the at
least one tear-initiation feature has an arcuate shape. In another
embodiment, the at least one tear-initiation feature is formed by
cutting through the film from a top surface of the film.
[0006] At least one aspect of the present invention also relates to
a method of forming cover tapes. The method involves cutting at
least one track into a film from a first major surface of the film,
cutting lines of weakness in the film from a second major surface
of the film, applying adhesive materials to the second major
surface of the film, and separating the film into multiple cover
tapes by slitting the film through the at least one track, thereby
forming at least one tear-initiation feature from the at least one
divided track.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of a carrier tape of an
embodiment of the present invention.
[0008] FIG. 2A is a top perspective view of a segment of a cover
tape of the carrier tape.
[0009] FIG. 2B is a top view of a segment of the cover tape of the
carrier tape.
[0010] FIG. 3 is a flow diagram of a method of forming the cover
tape.
[0011] FIG. 4A is a top view photograph taken of a cover tape
containing a tear-initiation features formed after an adhesive
strip was applied.
[0012] FIG. 4B is a top view photograph taken of a cover tape
containing a tear-initiation features formed before an adhesive
strip was applied.
[0013] FIG. 5 is a flow diagram of a method of forming multiple
cover tapes in a simultaneous manner.
[0014] FIG. 6 is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5.
[0015] FIG. 7 is a top view of an alternative multi-layer film
formed pursuant to the method shown in FIG. 5.
[0016] FIG. 8A is a side perspective view of a wound-up roll of
cover tape that illustrates an alternative method for forming
tear-initiation features.
[0017] FIG. 8B is a front perspective view of the wound-up roll of
cover tape.
[0018] FIG. 9A is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
first alternative "U"-shaped feature.
[0019] FIG. 9B is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
second alternative "U"-shaped feature.
[0020] FIG. 10 is an expanded view of a U''-shaped feature formed
pursuant to the method shown in FIG. 5.
[0021] FIG. 11 is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
first alternative, non-arcuate feature.
[0022] FIG. 12 is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
second alternative, non-arcuate feature.
[0023] FIG. 13 is a top view photograph of a carrier tape, which
includes a cover tape having non-arcuate tear-initiation
features.
[0024] FIGS. 14A-14D are top views of multi-layer films formed
pursuant to the method shown in FIG. 5, where the multi-layer films
depict additional alternative features.
[0025] FIG. 15A is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
"U"-shaped feature with a linear apex portion and linear trailing
ends.
[0026] FIG. 15B is a top view of a multi-layer film formed pursuant
to the method shown in FIG. 5, where the multi-layer film has a
"U"-shaped feature with a linear apex portion and curved trailing
ends.
[0027] FIG. 16 is a cross-sectional view of a cover tape having
recessed portions.
[0028] 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.
DETAILED DESCRIPTION
[0029] FIG. 1 is a perspective view of carrier tape 10, which is a
convenient system for storing and transporting electronic
components. As shown, carrier tape 10 includes base portion 12 and
cover tape 14, and is disposed in a coordinate system that includes
lateral axis 16x, longitudinal axis 16y, and vertical axis 16z. The
directional orientations are used herein for ease of discussion,
and are not intended to be limiting.
[0030] Base portion 12 is a flexible, self-supporting structure
that extends along longitudinal axis 16y, and includes perimeter
surface 18 and pockets 20. Perimeter surface 18 is a planar border
extending around pockets 20, and includes edge portions 22a and
22b. Edge portions 22a and 22b each extend along longitudinal axis
16y and are offset along lateral axis 16x. Additionally, lateral
edge portion 22b includes a row of aligned advancement holes 24
formed in perimeter surface 18. Advancement holes 24 allow carrier
tape 10 to engage with an advancement mechanism (not shown) for
advancing carrier tape 10 to a predetermined position during use.
Pockets 20 are indentations formed in base portion 12, within
perimeter surface 18, which are spaced apart along longitudinal
axis 16y. Pockets 20 are designed to conform to the size of the
stored electronic components, such as component 26 shown in FIG.
1.
[0031] Cover tape 14 is a single layer or multi-layer film that
extends along longitudinal axis 16y, and is disposed vertically
over perimeter surface 18 and pockets 20 of base portion 12. As
such, during storage and transportation, cover tape 14 seals stored
electronic components (e.g., component 26) within pockets 20. Cover
tape 14 includes top surface 28 and bottom surface 30, which are
opposing major surfaces of cover tape 14 offset along vertical axis
16z. Cover tape 14 also includes bonding portions 32a and 32b, and
medial portion 34, where medial portion 34 is laterally disposed
between bonding portions 32a and 32b. Bonding portions 32a and 32b
are the portions of cover tape 14 that are adhered to perimeter
surface 18 at edge portions 22a and 22b, respectively. Medial
portion 34 is a central portion of cover tape 14 that is configured
to be peeled back as shown in FIG. 1 (i.e., separated from bonding
portions 32a and 32b) for access to pockets 20.
[0032] Cover tape 14 also includes a plurality of tear-initiation
features 36, which, in this embodiment, are arcuate-shaped slits
extending from top surface 28 toward, and typically through, bottom
surface 30 at bonding portions 32a and 32b, and are situated at
intermittent locations along longitudinal axis 16y. Tear-initiation
features 36 allow medial portion 34 to be readily peeled from
bonding portions 32a and 32b, without requiring an excessive amount
of removal force. When the cover tape 14 is peeled back from
perimeter surface 18 of base portion 12, bonding portions 32a and
32b respectively delaminate from edge portions 22a and 22b of
perimeter surface 18 until the peel intersects tear-initiation
features 36. At this point, cover tape 14 starts to tear and the
tear is directed towards the center of cover tape 14 by the angle
and shape of tear-initiation features 36. The tear continues until
it runs into score lines (not shown in FIG. 1), which then provide
the directions along which cover tape 14 will tear continually.
[0033] Tear-initiation features 36 allow cover tape 14 to rely on a
tear mechanism rather than an adhesive de-bonding mechanism to peel
cover tape 14 from base portion 12. This reduces the need for
specialized adhesives to bond cover tape 14 to base portion 12,
which otherwise require a balance between adhesion and removal
forces. As such, cover tape 14 can be adhered to base portion 12
with strong adhesive forces, while still allowing medial portion 34
to be readily removed with moderate and consistent removal
forces.
[0034] FIGS. 2A and 2B are respectively a top perspective view and
a top view of a segment of cover tape 14. According to the
embodiment shown in FIG. 2A, cover tape 14 is a multi-layer film
that includes topcoat layer 38, core layer 40, bottom coating 42,
and adhesive strips 44a and 44b. Core layer 40 is the base layer
for cover tape 14, and is desirably uniaxially or biaxially
oriented to facilitate downweb tearing along longitudinal axis 16y,
and to reduce or prevent transverse tearing along lateral axis 16x.
Core layer 40 of cover tape 14 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. Core layer 40
can also be transparent, intrinsically non-conductive, electrically
conductive, static dissipative, and combinations thereof. Core
layer 40 may be made electrically conductive or static dissipative
by compounding materials such as carbon black or metals into the
polymer film material that forms core layer 40.
[0035] Topcoat layer 38 is optionally provided along top face 28 of
cover tape 14. Topcoat layer 38 may be or may 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. Topcoat layer 38 may also be a
protective layer that protects the cover tape 14 and retained
electrical components during storage and transportation. Suitable
materials for topcoat layer 28 include weathering and abrasion
resistant materials, such as polyurethanes, cross-linked materials
(e.g., cured acrylates and epoxies), silicones, silane-conforming
materials, and combinations thereof. While topcoat layer 38 is
shown across the entire top portion of core layer 40, topcoat layer
38 may alternatively be disposed over one or more smaller portions
of core layer 40 (e.g., to align with adhesive strips 44a and 44b
when cover tape 14 is rolled up).
[0036] Bottom coating 42 is also optionally provided along the
bottom face 30 of cover tape 14. Bottom coating 42 can be an SD
coating or other type of coating, and can be at least partially
blended with core layer 40. Alternatively, a metallized layer,
which can dissipate static electricity, may be substituted for
bottom coating 42. Suitable materials for a metallized layer
include metals such as aluminum, stainless steel, nickel-chrome,
and nickel-cadmium, which are applied by vapor coating or
sputtering techniques. Additionally, one or both of topcoat layer
38 and core layer 40 may also include metals for dissipating
electricity.
[0037] While cover tape 14 is shown with the above-discussed
layers, in alternative embodiments, cover tape 14 may include
different types of functional and non-functional layers as
necessary for particular storage applications. In another
alternative embodiment, cover tape 14 is a single-layer film that
only includes core layer 40. In this embodiment, top surface 28 and
bottom surface 30 are the opposing major surfaces of core layer 40.
This embodiment is beneficial for reducing material and processing
costs in forming cover tape 14.
[0038] Adhesive strips 44a and 44b are film-based strips of
adhesive materials that are bonded to bottom surface 30 at bonding
portions 32a and 32b, respectively. Adhesive strips 44a and 44b
extend along longitudinal axis 16y, and are the portions of cover
tape 14 that adhere to edge portions 22a and 22b of base portion
12. Suitable materials for adhesive strips 44a and 44b include
pressure sensitive adhesives and heat-activated adhesives (e.g.,
ethylene vinyl acetate copolymers). Upon assembly with base portion
12 (shown above in FIG. 1), adhesive strips 44a and 44b adhere
bonding portions 32a and 32b of cover tape 12 to edge portions 22a
and 22b of base portion 12.
[0039] As further shown in FIG. 2A, cover tape 14 includes score
lines 46a and 46b, which are lines of weakness formed in bottom
surface 30, and which extend through bottom coating 42 and
partially into core layer 40. Score lines 46a and 46b are disposed
laterally adjacent to adhesive strips 44a and 44b, respectively,
and extend along longitudinal axis 16y. In an alternative
embodiment, score lines 46a and 46b extend partially into core
layer 40, but are formed before bottom coating 42 is secured to
core layer 40. As such, in this embodiment, score lines 46a and 46b
do not extend through bottom coating 42. Tear-initiation features
36 extend through topcoat layer 38, core layer 40, and bottom
coating 42, and each have an arcuate shape along top surface 28 and
bottom surface 30.
[0040] As shown in FIG. 2B, score lines 46a and 46b (shown with
hidden lines) are disposed laterally inward relative to adhesive
strips 44a and 44b (shown with phantom lines). As a result, when
the tear of cover tape 14 reaches score lines 46a and 46b, the
force required to peel medial portion 34 only needs to exceed the
tear force of score lines 46a and 46b. The strength of the adhesive
bond at bonding portions 32a and 32b no longer directly affects the
required peel force.
[0041] As further shown in FIG. 2B, tear-initiation features 36
extend from the lateral edges of cover tape 14 to points laterally
inward that are disposed over adhesive strips 44a and 44b. This
keeps cover tape 14 anchored to base portion 12, and reduces the
risk of cover tape 14 accidentally peeling at a premature point in
time (e.g., during storage or transportation). Tear-initiation
features 36 also do not intersect score lines 46a and 46b to
preserve the structural integrity of cover tape 14.
[0042] To obtain access to pockets 20 of base portion 12 (shown
above in FIG. 1), a removal force is applied to medial portion 34
of cover tape 14. This initially de-bonds bonding portions 32a and
32b from edge portions 22a and 22b of base portion 12, thereby
peeling cover tape 14 from base portion 12 as represented by arrows
48a. Continued application of the removal force causes further
de-bonding until the peel reaches the first set of tear-initiation
features 36 along longitudinal axis 16y.
[0043] When the peel reaches tear-initiation features 36, the peel
then follows the arcuate shapes of tear-initiation features 36,
thereby moving the peel laterally inward toward the center of cover
tape 14 as represented by arrows 48b. When the peel reaches the end
of tear-initiation features 36, cover tape 14 then begins to tear
in the same direction as the trailing edges of tear-initiation
features 36, as represented by arrows 48c. Continued application of
the removal force causes the tearing to continue until score lines
46a and 46b are reached. Because score lines 46a and 46b have lower
tear strengths, the applied removal force then causes the tear to
follow score lines 46a and 46b, as represented by arrows 48d. This
separates medial portion 34 away from bonding portions 32a and 32b,
while bonding portions 32a and 32b remain adhered to base portion
12.
[0044] FIG. 3 is a flow diagram of method 50, which is a suitable
method for forming cover tape 14. As shown, method 50 includes
steps 52-58, and initially involves forming the multi-layer film of
cover tape 14 (i.e., topcoat layer 38, core layer 40, and bottom
coating 42) (step 52). The layers of cover tape 14 may be formed in
a variety of manners, such as co-lamination techniques (e.g.,
coextrusions and wet castings), deposition techniques (e.g., vapor
coatings and sputtering techniques), and combinations thereof.
[0045] Tear-initiation features 36 are then cut into the lateral
edges of the multi-layer film of cover tape 14 from top surface 28
(step 54). Forming tear-initiation features 36 from top surface 28
reduces the amount of debris contamination on top surface 28,
thereby reducing the risk of contaminating guides and sealing shoes
of sealing equipment used to seal cover tape 14 to base portion
12.
[0046] Once tear-initiation features 36 are formed, score lines 46a
and 46b are then cut into cover tape 14 from bottom surface 30
(step 56). Because score lines 46a and 46b do not extend through
core layer 40 or topcoat layer 38, score lines 46a and 46b may be
cut from bottom surface 30 without forming debris contamination on
top surface 28. In an alternative embodiment, score lines extend
through topcoat layer 38 and into core layer 40. In this
embodiment, the score lines are cut into top surface 28 rather than
bottom surface 30. While steps 54 and 56 are described above in the
order shown in FIG. 3, steps 54 and 56 may alternatively be formed
in an opposite order (i.e., cut score lines 46a and 46b prior to
cutting tear-initiation features 36), or in a substantially
simultaneous manner.
[0047] Once tear-initiation features 36 and score lines 46a and 46b
are formed, adhesive strips 44a and 44b are then coated onto bottom
surface 30 at bonding portions 32a and 32b (step 58). This may be
performed with a standard lamination process. Applying adhesive
strips 44a and 44b after tear-initiation features 36 are formed
also reduces contamination that may otherwise occur if
tear-initiation features 36 are cut after applying adhesive strips
44a and 44b to bottom surface 30. Cutting tear-initiation features
36, from bottom surface 30, after applying adhesive strips 44a and
44b pushes adhesive material through tear-initiation features 36,
and out of top surface 28. This also pushes film debris out through
top surface 28, where it may potentially collect in the guides and
sealing shoes of the tape sealing equipment. Thus, coating adhesive
strips 44a and 44b onto bottom surface 30 after tear-initiation
features 36 are formed from top surface 28 (or from bottom surface
30) reduces the risk of producing contaminating debris.
Additionally, application of adhesive strips 44a and 44b after
tear-initiating features 36 have been formed will encapsulate
within the adhesive strips any film debris deposited on bottom
surface 30 when tear-initiating features 36 were formed.
[0048] After cover film 14 is formed, it is then sealed to base
portion 12 (after electrical components are placed in pockets 20)
to form carrier tape 10. Suitable sealing systems for sealing cover
film 14 to base portion 12 include systems commercially available
from Ismeca USA, Inc., Carlsbad, Calif.
[0049] FIGS. 4A and 4B are top view photographs taken of cover
tapes containing tear-initiation features (taken with 20.times.
magnification). In the example shown in FIG. 4A, the cover tape
includes portions 60a and 60b, and tear-initiation feature 62.
Portion 60a is a portion of the multi-layer film adjacent a lateral
edge of the cover tape, and portion 60b is a portion where an
adhesive strip is disposed below the multi-layer film. As shown,
tear-initiation feature 62 extends through portion 60a, and has a
trailing end that terminates in portion 62b (i.e., above the
adhesive strip).
[0050] In this example, tear-initiation feature 62 was cut into the
multi-layer film from bottom surface 30 after the adhesive strip
was applied to bottom surface 30, thereby forming tear-initiation
feature 62 through the adhesive strip as well. Because of this, the
section of tear-initiation feature 62 that extends into portion 60b
is spread apart, and adhesive material is pushed upwards through
tear-initiation feature 62. The penetration of the cutting blade
through the adhesive strip pushes the adhesive away from the area
of tear-initiation feature 62, thereby causing a small region with
insufficient adhesive. This area has a reduced adhesive bond to the
corresponding base portion, and is a potential point of
delamination, which can result in shut downs and damage to the
sealing equipment.
[0051] In the example shown in FIG. 4B, the cover tape includes
portions 64a and 64b, and tear-initiation feature 66, which
correspond to portions 60a and 60b, and tear-initiation feature 62
(shown above in FIG. 4A). In contrast to the example shown in FIG.
4A, tear-initiation feature 66 was cut into the multi-layer film
from top surface 28 before the adhesive strip was applied. As
shown, the section of tear-initiation feature 66 that extends into
portion 64b is cleanly cut and no adhesive is pushed upwards. Thus,
forming tear-initiation feature 66 from top surface 28 (or from
bottom surface 30) prior to applying the adhesive strips reduced
the amount of contaminating adhesive and debris formed on the top
surface of the cover tape. In addition, most of the debris created
when forming tear-initiation feature 66 was captured or
encapsulated by the adhesive strip, thereby making it cleaner.
Furthermore, debris in the region of the adhesive strip did not
appear to reduce the adhesive strength of the adhesive strip.
[0052] FIG. 5 is a flow diagram of method 68, which is a suitable
method for forming multiple cover tapes simultaneously. As shown,
method 68 includes steps 70-78, and initially involves forming a
multi-layer film containing the layers of the cover tapes (step
70). The multi-layer film may be formed using the same techniques
discussed above in step 52 of method 50 (shown above in FIG. 3).
Multiple tracks are then cut into the multi-layer film from the top
surface of the film (step 72). Multiple score lines are then cut
into the multi-layer film from the bottom surface of the film (step
74). In an alternative embodiment, score lines are cut into the
multi-layer film from the top surface of the film. While steps 72
and 74 are described above in the order shown in FIG. 5, steps 72
and 74 may alternatively be formed in an opposite order (i.e., cut
the score lines prior to cutting the tracks), or in a substantially
simultaneous manner. After the tracks and score lines are formed,
multiple adhesive strips are then coated onto the bonding portions
of the bottom surface of the film (step 76). Finally, the film is
separated into the multiple cover tapes by slitting the film
through the tracks (step 78). As discussed further below in FIG. 6,
slitting the film between the adhesive strips (and through the
tracks) bisects each of the tracks, thereby forming a pair of rows
of tear-initiation features on the lateral edges of each cover
tape.
[0053] FIG. 6 is a top view of film 80, which is a multi-layer film
formed pursuant to step 70 of method 68. Film 80 includes top
surface 82, tracks 84, score lines 86 (shown with hidden lines),
adhesive strips 88 (shown with hidden lines), and slit lines 90. As
discussed above, multiple tracks 84 are cut into top surface 82,
pursuant to step 72 of method 68. As shown, tracks 84 are rows of
"U"-shaped features 91, where each "U"-shaped feature 91 is
subsequently divided to form a pair of arcuate-shaped
tear-initiation features. As such, this allows a single cutting
blade to form tear-initiation features for a pair of adjacent cover
tapes. The distance along film 80 between "U"-shaped features 91
may vary depending on the particular sizing requirements of the
resulting cover tapes. Suitable separation distances include at
least about 0.1 inches, with more suitable distances typically
ranging from about 0.5 inches to about 3 inches. Suitable lateral
widths of "U"-shaped features 91 include at least about 0.1
millimeters, with more suitable widths typically ranging from about
0.5 millimeters to about 2.0 millimeters. In one embodiment, the
multi-layer film includes a single "U"-shaped features 91. As
discussed above, forming tear-initiation features from top surface
82 (and also prior to applying adhesive strips 88) reduces the
amount of contaminating debris that forms on top surface 82.
[0054] Multiple score lines 86 are then cut in multi-layer film 80
from the bottom surface (not shown in FIG. 6), pursuant to step 74
of method 68. As shown, score lines 86 are disposed laterally
beyond "U"-shaped features 91, and beyond the intended locations of
adhesive strips 88. Adhesive strips 88 are then coated onto the
bottom surface of multi-layer film 80, pursuant to step 76 of
method 68. At this point multi-layer film 80 includes multiple
repeating patterns containing tracks 84, score lines 86, and
adhesive strips 88. Multi-layer film 80 is then separated into
multiple cover tapes (e.g., cover tapes 92a and 92b) by slitting
film 80 along slit lines 90, pursuant to step 78 of method 68. As
shown in FIG. 6, slit lines 90 bisect tracks 84, thereby separating
each "U"-shaped feature 91 into a pair of arcuate-shaped
tear-initiation features that extend from each lateral edge of the
separated cover tapes.
[0055] Method 68 shown above in FIG. 5 and discussed in FIG. 6 is
an efficient technique for forming multiple cover tapes from a
single multi-layer film. The number of cover tapes that may be
prepared pursuant to method 68 will vary depending on the lateral
width of film 80, the desired lateral widths of the cover tapes,
and on the lateral widths of the cutting dies.
[0056] Tracks 84 may be cut into film 80 in a variety of manners.
For example, cutting may be performed with one or more blades, a
blade burst, a rotary die, a stamping die, or combinations thereof.
In one embodiment, a sealing shoe of a standard sealing apparatus
is modified with small blades to function as a rotary die. In this
embodiment, tracks 84 are cut into a cover tape (e.g., cover tape
92a) from top surface 82 after adhesive strips 88 are applied. When
tracks 84 are formed after the adhesive strips are applied, the
sealing shoe is desirably treated so that adhesive strips 88 do not
stick to the sealing shoe (e.g., Teflon, plasma, and other
lubricants). As cover tape 92a is positioned above a base portion
corresponding to base portion 12 (shown above in FIG. 1), cover
tape 92a and the base portion pass through the sealing shoe. The
sealing shoe then seals cover tape 92a to the base portion and cuts
tracks 84 into cover tape 92a in a substantially simultaneous
manner. Because the cutting process occurs during the sealing
process, the adhesive material does not press through the formed
features before the sealed portion of cover tape 92a exits the
sealing shoe. As such, the concern for contaminating debris is
reduced.
[0057] In an alternative embodiment, a cutting die (corresponding
to a rotary die or a stamping die) may be located on one of the
multiple idler rollers that feed cover tape 92a to the sealing
shoe, thereby cutting tracks 84 into cover tape 92a just before
cover tape 92a is sealed to the base portion. In additional
alternative embodiments, different types of cutting mechanisms may
be used to cut tracks 84 into multi-layer film 80. Examples of
suitable alternative cutting mechanisms include laser-cutting
systems, rotating blades, and ultrasound-cutting systems.
[0058] FIG. 7 is a top view of multi-layer film 94, which is also a
multi-layer film formed pursuant to step 70 of method 68. Film 94
includes top surface 95, tracks 96, score lines 97 (shown with
hidden lines), slit lines 98, and "U"-shaped feature 99, which are
the same as top surface 82, tracks 84, score lines 86, slit lines
90, and "U"-shaped feature 91, as shown above in FIG. 6. As shown
in FIG. 7, film 94 also includes adhesive strips 100 (shown with
hidden lines), which extend across slit lines 90 and encompass
tracks 96. Film 94 is separated into multiple cover tapes by
slitting film 94 along slit lines 98, pursuant to step 78 of method
68. As shown in FIG. 7, slit lines 98 bisect tracks 84 and adhesive
strips 100. As such, each "U"-shaped feature 99 is separated into a
pair of arcuate-shaped tear-initiation features, and each adhesive
strip 100 is separated into a pair of adhesive strips that extend
from each lateral edge of the separated cover tapes.
[0059] FIGS. 8A and 8B are respectively a side perspective view and
a front perspective view of roll 104, which is a wound roll of
cover tape 106 that includes score lines (not shown) and
tear-initiation features 108. To better illustrate tear-initiation
features 108, the layers of cover tape 106 on roll 104 are not
shown in the figures. Cover tape 106 may be formed pursuant to
method 68 (shown above in FIG. 5), except that step 72 (cutting the
tracks) is omitted prior to separating the multi-layer film into
individual cover tapes (e.g., cover tape 106). In this embodiment,
tear-initiation features 108 are formed by cutting tear-initiation
features 108 into the lateral sides of roll 104. As such, this
embodiment is suitable for forming tear-initiation feature in
existing (e.g., commercially available) cover tapes. This allows
the existing cover tapes to be opened in a desired direction with
the use of tear-initiation features.
[0060] One or more groups of tear-initiation features formed by a
single blade may be cut at a time. Alternatively, the cutting may
be performed with a cutting mechanism that holds multiple blades
angled in the proper direction, thereby cutting all tear-initiation
features 108 into one of the lateral sides of roll 104 in a single
cutting motion. This embodiment is beneficial because
tear-initiation features 108 can be cut in every layer of roll 104
with minimal equipment. Because most rolls (e.g., roll 104) are
wound with good accuracy, a pre-set depth of a blade will cut all
the layers within reasonable tolerances. Nonetheless, exemplary
samples of cover tapes formed in this manner initiated a tear even
when the tear-initiation features were not cut to the exact desired
depth. As such, the cutting-depth tolerances for tear-initiation
features 108 allow for processing variations.
[0061] While a number of tear-initiation features 108 disposed
around roll 104 are desirable to ensure that there is always a tear
initiation feature 108 in case the cover tape is cut, a single cut
on a lateral side of roll 104 is sufficient to form tear initiation
features 108 for use. A single set of tear initiation features 108
is beneficial for placing a tear initiation feature 108 at the
beginning of the sealed reel so a customer can readily initiate the
tear. This also improves the strength and integrity of cover tape
106.
[0062] FIGS. 9A and 9B are top views of multi-layer films, each of
which depict alternative "U"-shaped features that may be formed
pursuant to the step 72 of method 68 (shown above in FIG. 5). As
shown in FIG. 9A, film 110 includes features 112a-112c and slit
line 114, where features 112a-112c are sharper than "U"-shaped
features 91 (shown above in FIG. 6). The terms "sharp", "sharper",
and the like refer to "U"-shaped features that have narrow, angular
apexes that cause the features to resemble "V"-shapes. The
"U"-shaped features may also be more rounded so that they are
semi-circular or between a "U" shape and a semi-circular shape.
[0063] As shown, feature 112a is centered around slit line 114,
feature 112b is laterally offset upward in the view shown in FIG.
9A, and feature 112c is laterally offset downward in the view shown
in FIG. 9A. Because of this offsetting, and because of the sharp
"U"-shapes, slit line 114 does not intersect features 112b and 112c
at the apexes of the "U" shapes. As a result, when the cover tapes
are separated along slit line 114, the resulting divided
tear-initiation features are uneven. Nonetheless, the sharp
"U"-shapes create a sharp point having little surface area for the
cover tape, which tends to lift when stressed (e.g., when wound in
a roll after the cover tape is sealed to a bottom portion).
Accordingly, features 112a-112c reduce the risk of cover tape
lifting, which is undesirable and can cause equipment shut
downs.
[0064] As shown in FIG. 9B, film 116 includes features 118a-118c
and slit line 120, where features 118a-118c are flatter than
"U"-shaped features 91 (shown above in FIG. 6), and slit line 120.
The terms "flat", "flatter", and the like refer to "U"-shaped
features that have broad, extended apexes. The flatter shapes of
features 118a-118c reduce the need to accurately center features
118a-118c around slit line 120. As shown, feature 118a is centered
around slit line 120, feature 118b is laterally offset upward in
the view shown in FIG. 9B, and feature 118c is laterally offset
downward in the view shown in FIG. 9B. Nonetheless, because
features 118a-118c have flat "U"-shapes, when the cover tapes are
separated along slit line 120, the resulting tear-initiation
features each extend from the lateral edges of the cover tapes in
the same directions. As such, the tear forces required to peel the
cover tapes from the offset tear-initiation features (i.e.,
features 118b and 118c) are substantially the same as those for
centered tear-initiation features (i.e., feature 118a). Therefore,
the use of flat features, such as features 118a-118c, allows for
greater accuracy tolerances for aligning with slit line 120.
Furthermore, the flat "U"-shapes also allows for a greater surface
contact area with the adhesive materials, thereby reducing the risk
of cover tape lifting.
[0065] FIG. 10 is an expanded view of feature 122, which is a
"U"-shaped feature formed pursuant to step 72 of method 68 (shown
above in FIG. 5). As shown in FIG. 10, feature 122 is divided along
slit line 124 to form individual, arcuate-shaped tear-initiation
features 126a and 126b, which are disposed on adjacent cover tapes.
As used herein, the term "arcuate" refers to a curved shape of a
tear-initiation feature (e.g., tear-initiation feature 122a), where
a leading end of the tear-initiation feature adjacent the edge of
the cover tape (shown as leading end 128) is oriented in a
different direction than a trailing end of the tear-initiation
feature (shown as trailing end 130). Because of the curvature of
tear-initiation feature 126a, the directions of leading end 128 and
trailing end 130 may be determined by the tangents of
tear-initiation feature 126a at the leading end 128 and trailing
end 130 (shown as tangent lines 132 and 134, respectively).
Accordingly, a tear-initiation feature is defined as being arcuate
if a first tangent line at the leading end (i.e., tangent line 132)
is oriented in a different direction than a second tangent line at
the trailing end (i.e., tangent line 134). In one embodiment, the
term "arcuate" includes shapes that have corner angles.
[0066] FIGS. 11 and 12 are top views of multi-layer films, each of
which depict alternative, non-arcuate features that may be formed
pursuant to the step 72 of method 68 (shown above in FIG. 5). As
shown in FIG. 11, film 134 includes "V"-shaped track features 136
and slit line 138, where each feature 136 has a corner angle apex
centered around slit line 138. As a result, when the cover tapes
are separated along slit line 138, the resulting tear-initiation
features, defined by the track features, are linear notches
extending at the same angle from the edges of the cover tapes. As
shown in FIG. 12, film 140 includes notch track features 142 and
slit line 144, where each notch feature extends from slit line 144.
In this embodiment, when the cover tapes are separated along slit
line 144, the resulting tear-initiation notch features 142 separate
along with each cover film.
[0067] FIG. 13 is a top view photograph of carrier tape 146, which
includes base portion 148 and cover tape 150. Cover tape 150
includes notch features 152, which are tear-initiation features
that may be formed with films 134 and 140 (shown above in FIGS. 11
and 12). As discussed above, notch features 152 are formed by
cutting the film from the top surface, prior to applying the
adhesive strips. This reduces the risk of forming contaminating
debris on the top surface of the film.
[0068] FIGS. 14A-14D are top views of multi-layer films, each of
which depict additional alternative features that may be formed
pursuant to the step 72 of method 68 (shown above in FIG. 5). As
shown in FIG. 14A, films 154a-154d each include different tracks
cut into the films (shown as tracks 156a-156d). Tracks 156a-156d
illustrate the wide variety of tracks and tear-initiation features
that are suitable for use with the present invention. FIG. 14B
shows film 158 with features 160a-160c, where features 160a-160c
are cut into film 158 to form notch features that extend at varying
angles (ranging from about 15.degree. to about 45.degree.). FIGS.
14C and 14D show films 162 and 164, respectively, which
respectively include features 166a-166c and features 168a-168f. As
shown, features 166a-166c and features 168a-168f are inverted from
the "U"-shape features shown above in FIG. 14A. As such, features
166a-166c and features 168a-168f exhibit triangular or pyramidal
shapes that extend at varying angles. When features 166a-166c and
features 168a-168f are divided, however, the resulting
tear-initiation features are arcuate shaped, and function in the
same manner as those discussed above.
[0069] FIGS. 15A and 15B are top views of multi-layer films, each
of which depict additional alternative "U"-shaped features that may
be formed pursuant to the step 72 of method 68 (shown above in FIG.
5). As shown in FIG. 15A, film 170 includes features 172 and slit
line 174, where features 172 includes linear apex portion 176 and
linear trailing ends 178a and 178b. As shown, linear trailing ends
178a and 178b extend from linear apex portion 176 at corner angles
180a and 180b, respectively.
[0070] As shown in FIG. 15B, film 182 includes features 184 and
slit line 186, where features 184 includes linear apex portion 188
and curved trailing ends 190a and 190b. As shown, curved trailing
ends 190a and 190b extend from linear apex portion 188 at corners
192a and 192b, respectively. Features 172 and 184 are further
illustrative of the variety of different features that may used
pursuant the present invention.
[0071] FIG. 16 is a cross-sectional schematic view of another
embodiment of a cover tape of the present invention having recessed
portions. The cover tape 220 includes an elongate film 222 that has
opposed longitudinal edges 224 and 226, and opposed top and bottom
faces 228 and 230, respectively. Longitudinally extending tear
enabling features 232 and 234 and longitudinally extending recesses
236 and 238 are located relative to the bottom face 230 of the film
222. The tear enabling features 232 and 234 are spaced apart, and a
central portion 240 of the film 222 is defined therebetween. A top
coating 242 is optionally provided along top face 228 of film 222.
A bottom coating 244 is also optionally provided along the bottom
face 30 of the film 22. Longitudinally disposed adhesive stripes
246 and 248 are provided along the recesses 236 and 238.
[0072] The recesses 236 and 238 are located at the longitudinal
edges 224 and 226, respectively, of the film 222. The recesses 236
and 238 are each open facing the bottom face 230 and longitudinal
edges 224 and 226, respectively, of the film 222. 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.sub.R, because it would
facilitate winding of the cover tape.
[0073] In the embodiment shown in FIG. 16, a bottom portion 250 and
a side portion 252 define each of the recesses 236 and 238. The
adhesive stripes 246 and 248 can be disposed on the bottom portions
250 of the recesses 236 and 238, respectively. The bottom portions
250 of the recesses 236 and 238 can have microtexture (not shown in
FIG. 16) for better adhering the adhesive stripes 246 and 248 to
the film 222. It should be recognized that other recess shapes can
be utilized, so long as the recesses 236 and 238 are open facing an
adjacent elongate edge 224 or 226 of the film 222 and the bottom
face 230 of the film 222.
[0074] The film 222, including recesses 236 and 238 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 236 and 238 can be formed using
different processes.
[0075] The adhesive stripes 246 and 248 on bottom portion 250 of
recesses 236 and 238 can be, for instance, pressure sensitive
adhesives (PSAs), heat activated and microencapsulated adhesives.
The adhesive stripes 246 and 248 can have thicknesses greater than,
less than or equal to a depth D.sub.R of the recessed areas 236 and
238. Typically, the thickness is less than or equal to depth
D.sub.R. The adhesive stripes 246 and 248 have widths equal to or
less than widths W.sub.R of the recessed areas 236 and 238. Having
widths less than widths D.sub.R of recessed areas 236 and 238
provides substantially adhesive-free zones longitudinally extending
along the bottom portions 250 of the recesses 236 and 238 on either
side of each of the adhesive stripes 246 and 248 when the cover
tape 220 is not applied to a surface (i.e., is not under
tension).
[0076] The tear enabling features 232 and 234 are located relative
to the bottom face 230 of the film 222, and can be located adjacent
the recesses 236 and 238 at the side portions 252 thereof. However,
in further embodiments, the tear enabling features 232 and 234 can
be located nearly anywhere along the top face 228, bottom face 230,
or both faces of the film 222, so long as they are each spaced from
the longitudinal edges 224 and 226 of the film 222. As shown in
FIG. 16, the tear enabling features 232 and 234 are continuous
scoring lines that extend longitudinally along film 222. Such
scoring lines can be formed by cutting into the film 222 (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 232 and 234 can be weakened
regions of the film 222 (e.g., interfaces of different materials,
thinner regions, microperforations, etc.), a transition between two
materials (e.g., a first material comprises central portion 240 of
the film 222 and a second material comprises the region of the film
222 between the bottom portions 250 of the recesses 236 and 238 and
the top face 228), or other structures that facilitate tearing.
[0077] In one embodiment, provided by way of example and not
limitation, the cover tape 220 can have the following dimensions.
An overall width W.sub.o of the film 222 (measured between elongate
edges 224 and 226) is about 1 inch (2.54 cm). A thickness T of the
film 222 is about 2 mil (0.0254 mm) (measured at the thickest
portion of the central region 240 of the film 222). The recesses
236 and 238 each have a width W.sub.R of about 0.0393701 inch (1
mm) and a depth D.sub.R of about 0.5 mil (0.0127 mm). The tear
enabling features 232 and 234 are score lines each having a depth
of about 1.5 mil (0.0381 mm) (measured from the bottom face 230 of
the film 222). It should be recognized that dimensions of the cover
tape 220 can vary, as desired. For instance, a width of the central
portion 240 of the film 222 can be selected such that it is at
least as wide as the pockets of a carrier tape with which the cover
tape 220 is used.
[0078] Other embodiments of cover tapes having recesses are
disclosed in co-pending U.S. patent application Ser. No.
11/228,956, which is incorporated herein by reference.
[0079] Although the present invention has been described with
reference to preferred 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.
* * * * *