Carrier tape system

A carrier tape system includes an elongated base strip and an elongated cover strip both formed of a plastic film material. The cover strip is substantially coextensive in length with the base strip. The cover strip has a top surface and opposed sidewalls extending downwardly from the top surface. The opposed sidewalls are spaced apart from each other a distance substantially equal to the width of the base strip. A cover strip further includes retaining means formed integrally therewith for mechanically engaging and holding down thin component parts seated in cavities formed in the base strip. The retaining means is comprised of a pair of spaced apart rail members which are formed coextensive with the cover strip extending longitudinally to the sidewalls and projecting downwardly and outwardly from the top surface thereof. The rail members are flared outwardly at a slight angle toward the respective opposed sidewalls. The top surface of the cover strip between the spaced apart rail members defines a clear viewing window for viewing the component parts in the cavities.

BACKGROUND OF THE INVENTION 
This invention relates generally to carrier tapes and more particularly, it 
relates to an improved carrier tape system for transporting electronic 
components, pharmaceutical, and the like during production and assembly 
operations. 
As is generally well-known, carrier tapes are commonly used to transport 
miniature or subminiature components or products from one station to 
another station in production and assembly operations. Such carrier tapes 
are typically formed of a base strip of plastic, paper or the like and a 
cover strip. The base strip is formed with a plurality of cavities or 
pockets for holding the components and the cover strip is secured to the 
base strip so as to avoid accidental falling of the components from the 
cavities. Heretofore, the cover strip was most commonly held in place by 
an adhesive, heat bond or spaced snap-type fasteners. Typical examples of 
these type of prior art carrier tapes are disclosed in U.S. Pat. Nos. 
3,465,874; 3,650,430; 3,700,019; 3,894,896; 3,910,410; and 4,298,120. 
In addition to the above patents, there are various prior art carrier tapes 
which utilize a continuous mechanical interlock for securing together the 
base strip and the cover strip. For example, in U.S. Pat. No. 4,733,778 to 
Hugo Boeckmann et al. issued on Mar. 1, 1988, and entitled "Reusable 
Carrier Tape," there is disclosed a carrier tape construction in which the 
base and cover strips are uniformly and consistently secured to each 
other. At least one of the strips is provided with an integrally formed, 
longitudinally extending continuous profile which cooperates with the 
surfaces of the other strip to secure the two strips in a locking 
arrangement. In addition, in U.S. Pat. No. 4,708,245 to Hugo Boeckmann et 
al. issued on Nov. 24, 1987, and entitled "Carrier Tape," there is 
disclosed a carrier tape which includes an elongated base strip, an 
elongated cover strip, and at least one elongated profile strip bonded to 
one of the other strips, preferably the base strip. The profile strip is 
provided with a longitudinally extending continuous, integrally formed 
profile which cooperates with the surfaces of the cover strip to secure 
the base and cover strips in a locking engagement. 
Further, in U.S. Pat. No. 4,842,135 to Herbert A. Borst issued on Jun. 27, 
1989, and entitled "Improved Carrier Tape and Cover Applying and Removal 
Devices For Same," there is disclosed an improved carrier tape comprising 
an elongated base strip and an elongated cover strip both formed of a 
plastic film material. The base strip is provided with longitudinally 
spaced cavities for components to be transported therein as well as a 
series of spaced, longitudinally extending sprocket drive holes for 
advancing the tape through an associated assembly machine. The cover strip 
has sidewalls extending downwardly and terminating in inwardly directed 
barbs or profiles. The spacing between the sidewalls is substantially 
equal to the width of the base strip. A raised, longitudinally extending 
hump is provided projecting upwardly from the top surface of the cover 
strip. When the hump is depressed, the sidewalls of the cover strip move 
laterally outwardly so as to clear the edges of the base strip and thus 
permit removal of the cover strip. On the other hand, when the hump is 
released, the sidewalls return to their relaxed positions securely 
interlocking with the base strip edges. 
Furthermore, in U.S. Pat. No. 4,958,053 to Hugo Boeckmann et al. and 
entitled "Carrier Tape and Method of Manufacturing the Same," there is 
disclosed a carrier tape having a cover strip and a base strip formed of a 
plastic material and designed to mechanically interlock with each other. 
The cover strip includes a top surface from which sidewalls extend 
downwardly. At least one of the sidewalls includes a segment extending 
outwardly away from the other sidewall so as to define a camming surface 
to which a force may conveniently be applied to urge the sidewalls apart, 
thereby facilitating removal of the cover strip from the base strip. The 
cover strip may further be provided with a hump of a dovetail 
configuration. 
In U.S. Pat. No. 4,897,074 to Richard K. Knight and entitled "Mechanism For 
Joining a Carrier Tape Cover to a Base Strip," there is disclosed a 
carrier tape system which includes an elongated base strip and an 
elongated cover strip both formed of a plastic film material. The cover 
strip is substantially coextensive in length with the base strip. The 
cover strip has a top surface and opposed sidewalls extending downwardly 
from the top surface. The opposed sidewalls are spaced apart from each 
other a distance substantially equal to the width of the base strip. The 
cover strip further includes a hump projecting upwardly from the top 
surface and extends longitudinally in a parallel relationship to the 
sidewalls. Each of the sidewalls has an inwardly extending hooked portion 
formed integrally therewith. The hooked portion has its top surface faced 
beneath the edge of the base strip to form a U-shaped recess to secure the 
cover strip to the base strip. All of the aforementioned U.S. Pat. Nos. 
4,733,778; 4,708,245; 4,842,135; 4,958,053; and 4,897,074 are assigned to 
the same assignee as the this invention and are hereby incorporated by 
reference. 
Also, there is taught in U.S. Pat. No. 4,463,851 to Waldo E. Cecil issued 
on Aug. 7, 1984, and entitled "Protective Enclosure for Electronic 
Devices," a protective enclosure for electronic devices which includes a 
tube formed from conductive polyvinyl chloride and having a bottom wall, 
side walls, and a top wall. The top wall of the tube includes a gap 
defined by spaced apart edges extending the entire length thereof. A 
transparent window formed from transparent polyvinyl chloride is mounted 
on the outer surface of the top wall and extends across the gap to permit 
observation of electronic devices supported on the central portion of the 
bottom wall. 
Aside from the above U.S. Patents referred to, there is also known in the 
prior art of British patent application No. 8825154.1 filed on Oct. 27, 
1988, and entitled "Tape for Storage of Electronic Components." A 
corresponding PCT application was filed on Oct. 27, 1989, claiming the 
priority date of the earlier British patent application and was published 
on May 3, 1990, under No. WO 90/04915. This PCT application disclosed a 
tape for storage of electronic flatpacks which includes a series of 
pockets along its length. Each of the pockets has a floor which is 
inwardly deformed to define a protrusion extending in a generally 
rectilinear fashion around the pocket floor. The protrusion is profiled to 
define a support surface disposed at a first clearance from the floor and 
a ridge extending along the outer peripheral boundary of the support 
surface. The top of the ridge is disposed at a second clearance from the 
floor and by a third clearance from the walls of the pockets. An 
electronic flatpack having a body and protruding connector pins is carried 
by the support surface with the pins being disposed over the ridge and 
extending into the third clearance. 
In use, the prior art carrier tapes are usually wound around a storage reel 
for shipping and handling. While the base strip is provided with cavities 
which are often contoured to hold the components in place, it has however 
been encountered heretofore that the components may still be moveable out 
of the cavities, especially when they are small thin fragile parts, so as 
to be susceptible to physical and electrostatic discharge (ESD) damage as 
the carrier tape is wrapped onto the storage reel. As a result, the small 
thin parts tend to shift or move between the base and cover strips during 
the winding process, thereby causing them to prematurely fall out of the 
cavities. All of the various prior art methods of securing the base strip 
and the cover strip previously discussed (both the adhesion technique and 
the mechanical interlock type) fail to effectively hold the small thin 
parts in the cavities of the base strip during the assembly operation. 
Accordingly, it would therefore be desirable to provide an improved carrier 
tape system in which the base strip has trough-like sections 
interconnected between the cavities and the cover strip has retaining 
means for movement within the trough-like sections so as to mechanically 
engage and hold down the components in the cavities during wrapping around 
a storage reel. 
SUMMARY OF THE INVENTION 
Accordingly, it is a general object of the present invention to provide an 
improved carrier tape system having retaining means which is relatively 
simple and economical to manufacture and assembly, but yet overcomes the 
disadvantages of the prior art carrier tapes. 
It is an object of the present invention to provide a carrier tape system 
which include a base strip and a cover strip having retaining means for 
mechanically engaging and holding down components in cavities formed in 
the base strip. 
It is another object of the present invention to provide an improved 
carrier tape system in which the base strip has trough-like sections 
interconnected between the cavities and the cover strip has retaining 
means for movement within the trough-like sections so as to mechanically 
engage and hold down the components in the cavities. 
It is still another object of the present invention to provide an improved 
carrier tape system in which the cover strip has a ridge for mechanically 
engaging and pressing against the top surfaces of components in cavities 
formed in the base strip. 
It is yet still another object of the present invention to provide an 
improved carrier tape system in which the cover strip includes a pair of 
spaced-apart rail members for mechanically engaging and fitting tightly 
against the top surfaces of components in cavities formed in the base 
strip. 
In accordance with these aims and objectives, the present invention is 
concerned with the provision of improved carrier tape system which 
includes an elongated base strip and an elongated cover strip which is 
substantially coextensive in length with the base strip. The cover strip 
has a top surface and opposed sidewalls extending downwardly from the top 
surface. The opposed sidewalls are spaced apart from each other a distance 
substantially equal to the width of the base strip. The cover strip 
further includes retaining means formed integrally therewith for 
mechanically engaging and holding down components in cavities formed in 
the base strip. 
In another aspect of the invention, the retaining means is comprised of a 
pair of spaced-apart rail members coextensive with the cover strip and 
projecting downwardly and outwardly at a slight angle from being 
perpendicular to the top surface thereof. Further, in still another aspect 
of the invention, the base strip is formed with a plurality of 
specially-designed cavities having a plurality of ridge segments disposed 
therein for retaining the body of a fine pitch surface mount device. 
In still yet another aspect of the invention, the cover strip having the 
spaced-apart rail members includes a clear viewing window strip of an 
anti-static or static dissipative material formed in its top surface and 
between the rail members with the remainder of the cover strip being made 
of a conductive plastic material. In yet still another aspect of the 
invention, such cover strip may be used with the base strip having the 
specially-designed cavities to store sensitive electronic devices to 
provide a carrier tape system which offers improved protection against 
damage from ESD by quickly conducting static charges away from the 
electronic devices.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now in detail to the drawings, there is shown in FIGS. 1 through 
4 an improved carrier tape system 10 which is constructed in accordance 
with the principles of the present invention. The carrier tape system 10 
is comprised of an elongated base strip 12 and a generally coextensive 
cover strip 14. The carrier tape system 10 is preferably formed of a 
suitable plastic film material such as carbon loaded polyvinyl chloride, 
polypropylene or a glycol-based polyester such as polyethylene 
terephthalate (PETG) which may be readily extruded and vacuum or pressure 
formed to the desired shape. The carrier tape resin may be formulated with 
appropriate additives to render the base and cover strips anti-static or 
static dissipative as may be required. The improved carrier system 10 
should be sufficiently flexible to permit it to be spooled or wound on a 
storage reel. 
The base strip 12 is formed with a plurality of cavities 16 which define 
individual pockets for the components to be conveyed therein. In this 
regard, the cavities 16 may be contoured, as required, to maintain the 
component in a particular orientation, should such orientation be 
necessary. A series of aligned sprocket holes 18 is provided extending 
through the base strip 12, adjacent to and outward of the cavities 16. The 
base strip 12 further includes a first edge 20 disposed outwardly of the 
sprocket holes 18 and a second edge 22 disposed outwardly of the cavities 
16. 
Further, it will be noted that each of the cavities 16 is of a generally 
circular shape and is formed with round support ledges 24 disposed about 
the interior circumference of the cavities. When the components 26 to be 
conveyed in the cavities are small, thin fragile parts, such as metallic 
disc-shaped dome switch pads, only the periphery of the lower surface of 
the pad is to be held by the support ledges 24 within the cavity so that 
the entire lower surface does not contact the bottom surface 28 of the 
cavity, thereby reducing the possibility of physical damage. 
The base strip 12 also includes a plurality of recesses or trough-like 
sections 30, each extending longitudinally between and interconnecting two 
adjacent cavities 16. The trough-like sections 30 serve to receive 
retaining means formed on the cover strip 14 for movement therein, as will 
be presented hereinafter. Each of the trough-likessection 30 is defined by 
vertical walls 32, 34 which are spaced apart from each other by a distance 
equal to less than the diameter of the cavities 16. 
The cover strip 14 is coextensive in length with the base strip 12. The 
cover strip 14 is provided at each side, with downwardly extending 
sidewalls 36 and 38. These sidewalls 36, 38 are spaced apart from each 
other a distance equal substantially to the width of the base strip 12. A 
cover strip 14 also includes a longitudinally extending upwardly 
projecting hump 40 along its entire length. The hump 40 is used to provide 
a "living hinge" for major portion 42 and minor portion 44 of the top face 
of the cover strip 14 defined on opposite sides of the hump. 
The sidewall 36 has formed integrally therewith an inwardly extending 
hooked portion 46. The undersurface of the cover strip 14 adjacent the 
sidewall 36 and the top surface of the hooked portion 46 form a continuous 
longitudinally extending U-shaped recess or slot 48. Similarly, the 
sidewall 38 has formed integrally therewith an inwardly extending hooked 
portion 50. The undersurface of the cover strip 14 adjacent the sidewall 
38 and the top surface of the hooked portion 50 form a continuous 
longitudinally extending U-shaped recess or slot 52. 
The cover strip 14 also includes a longitudinally extending retaining means 
formed of a downwardly extending U-shaped depression or ridge 54 disposed 
substantially in the intermediate area of the major portion 42. The ridge 
54 is defined by spaced apart vertical wall members 56, 58 joined together 
by a horizontally flat crossmember 60. When the base strip 12 with its 
cavities 16 thereof loaded with small thin parts 26 and the cover strip 14 
are joined together in the assembled condition, the ridge 54 in the cover 
strip 14 will travel or move in the corresponding trough-like sections 30 
in the base strip 12 so as to cause the lower surface of the flat 
crossmember 60 to mechanically engage and press against the top surfaces 
of the thin parts 60 seated in the cavities 16, as can best be seen from 
FIG. 2. As a consequence, the crossmember 60 of the ridge 54 serves to 
efficiently and effectively hold down the thin parts in the cavities and 
thus restricts any extraneous movement thereof. Therefore, the thin parts 
26 are in this manner prevented from prematurely falling out of the 
cavities 16 during wrapping of the carrier tape system 10 around a storage 
reel for subsequent shipment and/or use. 
The sizes of the U-shaped recesses 48 and 52 are such that when the cover 
strip 14 is mechanically interengaged with the base strip 14, the edges 
20, 22 of the base strip are received within the recesses 48 and 50, as 
best seen from FIG. 2. Further, in the assembled condition the hump 40 is 
positioned to be aligned over the line of sprocket holes 18 thereby 
providing clearance for engaging the protruding teeth of a sprocket drive 
wheel of an assembly mechanism with which the carrier tape system 10 is to 
be used. 
In FIG. 5, there is illustrated a second embodiment of a cover strip 14a in 
which retaining means is comprised of a pair of spaced apart projections 
or rail members 62, 64. The rail members 62, 64 extend downwardly from the 
lower surface of the major portion 42 in substantially its intermediate 
area. The rail members are spaced apart a distance which is approximately 
equal to the width of the crossmember 60 of FIG. 4. The rail members 
function in a similar manner for mechanically engaging and fitting tightly 
against the top surfaces of the thin parts seated in the cavities, thereby 
precluding disengagement of the parts from the cavities during the 
assembly operation. 
In FIG. 6, there is illustrated a third embodiment of a cover strip 14b in 
which retaining means is comprised of a pair of spaced-apart projections 
or rail members 62a, 64a. The rail members 62a, 64a extend downwardly and 
outwardly from the lower surface of the major portion 42 in substantially 
its intermediate area. It will be noted that each of the rail members 62a, 
64a is not disposed perpendicularly to the lower surface of the major 
portion 42 as in the embodiment of FIG. 5, but is arranged to be at a 
slight angle from being perpendicular to the lower surface thereof. In 
other words, the rail members 62a, 64a are angled or flared outwardly an 
additional 10.degree. approximately toward the respective sidewalls 38, 
36. This feature ensures that the lower ends 63 of the rail members 62a, 
64a are prevented from engaging the top surface of the trough-like 
sections 30 and thus do not impede movement of the cover strip relative to 
the base strip during assembly. 
The rail members 62a, 64a are likewise spaced apart a distance which is 
approximately equal to the width of the crossmember 60 of FIG. 4. The rail 
members 62a, 64a also function in the same manner as the rail members of 
FIG. 5 for mechanically engaging and fitting tightly against the top 
surfaces of the component parts seated in the cavities, thereby precluding 
disengagement of the component parts from the cavities during the assembly 
operation. 
Referring now to FIG. 7, there is depicted a second embodiment of a base 
strip 12a which is formed with a plurality of cavities 16a defining 
individual pockets for holding component parts to be conveyed therein. A 
series of aligned sprocket holes 18a is provided extending through the 
base strip 12a, adjacent to and outward of the cavity 16a. The base strip 
12a further includes a first edge 20a disposed outwardly of the sprocket 
holes 18a and a second edge 22a disposed outwardly of the cavity 16a. 
As can be seen, each of the cavities 16a has a generally rectangular or 
square shaped configuration and is defined by four sidewalls 17. Each of 
the cavities 16a includes a rectangularly-shaped support ledge surface 24a 
having a rectangularly-shaped recessed bottom surface 28a located in its 
central portion thereof. The bottom surface 28a is provided with a 
circular opening 29a which allows for manual removal of the component 
parts and for permitting sensing by electronic means of whether there is a 
part in each of the cavities. 
Adjacent each of the four outer edges of the support ledge surface 24a, 
there is disposed an inverted V-shaped connecting ridge segment 31 which 
is used to join integrally each side edge of the support ledge surface 24a 
to one side of a peripheral bottom surface 33 of the cavity. It will be 
noted that the peripheral bottom surfaces 33 lie in the same plane as the 
recessed bottom surface 28a. The other side of each of the peripheral 
bottom surfaces 33 is formed integrally with one of the respective four 
sidewalls 17. With this specially-designed contour, the cavities 16a have 
been fabricated to locate and hold a fine pitch surface mount device 26a, 
such as a semiconductor I.C. device commonly referred to as a quad flat 
pack (QFP) device having fine pitch leads 27 extending outwardly from the 
four sides of its rectangularly-shaped body 29, so that the fine pitch 
leads does not contact or touch any portion of the carrier tape system, 
thereby eliminating the possibility of physical damage. 
The base strip 12a also includes a plurality of recesses or trough-like 
sections 30a, each extending longitudinally between and interconnecting 
two adjacent cavities 16a. The trough-like sections 30a serves to receive 
the retaining means 62a, 64a formed on the cover strip 14a of FIG. 6 for 
movement therein. Each of the trough-like sections 30a is defined by 
vertical walls 32a, 34a which are spaced apart from each other by a 
distance equal to less than the width of the cavity 16a. 
There is shown in FIG. 8 of the drawings another embodiment of an improved 
carrier tape system 10a which is comprised of the elongated base strip 12a 
of FIG. 7 and the generally coextensive cover strip 14a of FIG. 6. It can 
be seen that the base strip 12a has its cavities 16a thereof loaded with 
the QFP device 26a (which is shown in phantom) and that the cover strip 
14a is secured to the base strip 12a in the assembled condition. It should 
be noted that only the periphery of the lower surface of the body 29 of 
QFP device 26a is held by the support ledge surface 24a within the cavity 
so that the remaining lower surface or central portion of the body 29 does 
not contact the recessed bottom surface 28a of the cavity, thereby 
reducing the chance of physical damage. Further, the fine pitch leads 27 
extend horizontally and outwardly over the corresponding plurality of 
ridge segments 31 and the ends thereof are suspended freely above the 
respective peripheral bottom surfaces 33. As a result, the leads 27 do not 
engage or contact any portion of the base strip 12a so as to likewise 
avoid physical damage thereto. 
During assembly, the angularly disposed pair of rail members 62a, 64a will 
travel or move freely in the corresponding trough-like sections 30a in the 
base strip 12a so as to cause the lower ends 63 thereof to mechanically 
engage and press against the top surface of the body 29 of the QFP device 
26a seated in the cavity 16a, as can best be seen from FIG. 8. As a 
consequence, the plurality of ridge segments 31 serves to efficiently and 
effectively retain or fence in the body 29 of the device 26a in the cavity 
16a and thus restricts any extraneous movement thereof. Therefore, the QFP 
devices 26a are in this fashion prevented from prematurely falling out of 
the cavity 16a during wrapping of the carrier tape systems 10a around a 
storage reel for subsequent shipment and/or use. 
In FIG. 9, there is illustrated a fourth embodiment of a cover strip 14c 
which is quite similar to the embodiment of FIG. 6. The cover strip 14c 
includes the retaining means comprised of a pair of spaced-apart, 
stand-off ribs or rail members 62a, 64a. The stand-off ribs 62a, 64a 
extend downwardly and outwardly from the lower surface of the major 
portion 42 in substantially its intermediate area. A transparent or clear 
viewing window strip 66 is integrally formed in the major portion 42 of 
the cover strip 14c between the stand-off ribs 62a, 64a. 
The entire cover strip 14b in the embodiment of FIG. 6 is preferably formed 
of an anti-static or static dissipative material. The cover strip 14c in 
FIG. 9 is different from FIG. 6 in that only the relatively narrow window 
strip 66 is made of the anti-static or static dissipative material and the 
remainder of the cover strip 14c is preferably made of a conductive 
plastic material, such as carbon loaded polyvinyl chloride. The cover 
strip 14c fabricated in this manner provides improved protection against 
damage from ESD by quickly conducting any static charges away from 
sensitive electronic devices contained within the cavities of the base 
strip. Further, such cover strip 14c facilitates viewing the interior of 
the cavities of the base strip so as to permit a customer or user to 
visually verify whether the cavities are filled with the electronic 
devices. 
It should be apparent to those skilled in the art that as an alternative to 
the embodiment of FIG. 6 the area in the major portion 42 of the cover 
strip 14b between the spaced-apart rail members 62a, 64a could be formed 
with an opening or a plurality of openings so as to facilitate viewing of 
the interior of the cavities in the base strip. However, this cover strip 
design would only be acceptable to customers who do not require the 
improved ESD protection offered by the embodiment of FIG. 9. 
There is depicted in FIG. 10 still another embodiment of an improved 
carrier tape system 10b which is comprised of the elongated base strip 12a 
of FIG. 7 and the generally coextensive cover strip 14b of FIG. 9. It can 
be seen that the base strip 12a has its cavities 16a loaded with the QFP 
devices 26a (which is shown in phantom) and that the cover strip 14b is 
secured to the base strip 12a in the assembled condition. This carrier 
tape system design offers improved ESD protection since the cover strip 
14b having the stand-off ribs 62a, 64a is fabricated entirely of the 
conductive plastic material, except for the clear viewing window 66 
located between the ribs. As will be noted, the ribs 62a, 64a serve to 
engage against the top surfaces of the QFP devices 26a and to hold the 
same away from the viewing window 66. As a result, any electrostatic 
charge may be quickly conducted away so as to protect the QFP devices 26a 
contained within the cavities 16a of the base strip 12a. Except for these 
differences, the carrier tape system 10b of FIG. 10 is identical in 
structure and function to the tape system 10a of FIG. 8. 
From the foregoing detailed description, it can thus be seen that the 
present invention provides an improved carrier tape system in which the 
base strip has trough-like sections interconnected between the cavities 
and the cover strip has retaining means for movement within the 
trough-like section. The retaining means serves to mechanically engage and 
hold down the components in the cavities, thereby preventing them from 
prematurely falling out of the cavities during wrapping of the carrier 
tape system around a storage reel. The retaining means is formed suitably 
of either a ridge or a pair of spaced apart rail members. 
While there has been illustrated and described what is at present 
considered to be preferred embodiments of the present invention, it will 
be understood by those skilled in the art that various changes and 
modifications may be made, and equivalents may be substituted for elements 
thereof without departing from the true scope of the invention. In 
addition, many modifications may be made to adapt a particular situation 
or material to the teachings of the invention without departing from the 
central scope thereof. Therefore, it is intended that this invention not 
be limited to the particular embodiments disclosed as the best modes 
contemplated for carrying out the invention, but that the invention will 
include all embodiments falling within the scope of the appended claims.