Advancing material of indeterminate length – With means to temporarily deform material laterally
Reexamination Certificate
2000-03-31
2002-07-16
Mansen, Michael R. (Department: 3653)
Advancing material of indeterminate length
With means to temporarily deform material laterally
C226S185000
Reexamination Certificate
active
06419138
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a carrier tape conveying device which is used in assembly processes of electronic components such as semiconductor elements, etc., and more particularly to a conveying device that conveys an electronic component carrier tape constructed from a soft, heat-resistant flexible material such as a synthetic resin (referred to as a “resin film”) in the direction of length of the carrier tape.
2. Prior Art
The carrier tape system widely used in semiconductor element assembly processes uses a carrier tape in which a conductive layer is formed on appropriate portions of the top surface of a band-form film made of a synthetic resin. In this system, various types of assembly processes are performed by separate working devices for the respective working processes. For instance, an arrangement and bonding of numerous silicon chips to the top surface or undersurface of the carrier tape (die bonding), a connection of the surface electrodes of the silicon chips to a conductive layer by conductive wires (a wire bonding method), and a sealing of these parts with a synthetic resin (packaging) are performed.
FIG. 6
shows one of the conventionally used carrier tape conveying devices used in such carrier tape systems.
In this carrier tape conveying device, pressing rollers
75
are disposed on the top surface sides of the side edge portions of the carrier tape
2
, and drive rollers
77
are disposed on the undersurface sides of these side edge portions. The rotating shafts of the pressing rollers
75
are supported so that they rotate on pressing frames
29
that are constantly driven downward. The rotating shafts of the drive rollers
77
are connected to motors
41
.
In this construction, both side edge portions of the carrier tape
2
are pressure-held between the pressing rollers
75
and drive rollers
77
as a result of the driving force of the pressing frames
29
. The carrier tape
2
is conveyed in the direction of its own length (i.e. in the direction perpendicular to the surface of the drawing sheet) by the driving of the motors
41
. When a silicon chip
70
bonded to the undersurface of the conveyed carrier tape
2
stops at a specified working position, a jig
24
containing a heater used for preparatory heating is raised. As a result, the silicon chip
70
on the undersurface of the carrier tape
2
is received in a retaining hole
26
formed in the jig
24
, and the upper surface of the carrier tape
2
is pressed by a clamp (not shown). Then, the carrier tape
2
and silicon chip
70
in this attitude are subjected to working such as wire bonding, etc. from above.
However, the carrier tape
2
is flexible and is softened by preparatory heating by the heater. Accordingly, a sag in the direction of width as indicated by the one-dot chain line
72
in
FIG. 6
is generated in the carrier tape
2
by the weight of the silicon chips
70
bonded to the carrier tape
2
. In cases where conveying is continued in this state, the silicon chips
70
may collide with the waiting jig
24
if the sagging is severe, and the silicon chips
70
are subjected to impacts and vibrations. Furthermore, in the case of such collisions or in cases where the extraction of the silicon chips
70
from the jig
24
is insufficient, the carrier tape
2
may be pulled by an excessive force, so that stretching or shifting of the holding position occurs in the carrier tape
2
, causing a drop in conveying precision and working precision.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a conveying device that is able to prevent sagging of the carrier tape across the width thereof during conveying before such sagging occurs.
The object is accomplished by a unique structure for a device for conveying a carrier tape for an electronic component in which the side edge portions of a carrier tape are pressure-held from its upper and under surfaces by a pair of rollers rotating in opposite directions so as to convey the tape in the direction of length thereof; and in the present invention, a supporting member which protrudes upward with respect to the pressure-holding position of the rollers is provided on the center side of the carrier tape with respect to the direction of width of the carrier tape in the pressure-holding positions of the rollers, so that the carrier tape is held by the pair of rollers and supporting member while being elastically deformed so as to allow its own recovery from the deformed state.
In this structure, the supporting member which protrudes upward in the pressure-holding positions of the pair of rollers (that pressure-hold the carrier tape) is installed further toward the center of the carrier tape with respect to the direction of width of the carrier tape. Accordingly, when the rollers apply a pressure to the side edge portions of the carrier tape, the portion of the carrier tape that is near the center of the carrier tape with respect to its width direction is lifted upward in response to this pressure with the contact points between the carrier tape and the supporting member acting as fulcrums. Furthermore, since the rollers hold the carrier tape while causing an elastic deformation thereof, the holding force of the rollers is reinforced by the recovery force of the carrier tape, and slipping between the respective rollers and the carrier tape is prevented. Sagging of the carrier tape across the width of the carrier tape can thus be prevented in advance.
Furthermore, since the rollers and the supporting member merely cause an elastic deformation of the carrier tape and do not cause plastic deformation of the carrier tape, the carrier tape recovers to its original flat shape after passing through the pressure-holding or the rollers. Accordingly, the original shape of the carrier tape can be maintained without any folds being formed in the carrier tape, and there is no danger of a drop in the conveying precision or working precision that would be caused by plastic deformation of the carrier tape.
The above-described pair of rollers comprises a first roller and a second roller. The first roller has a large-diameter portion and a small-diameter portion. The large-diameter portion is formed on the side of the roller that is located further toward the center of the carrier tape with respect to the width of the carrier tape, and the small-diameter portion is formed on the side of the roller that is located further toward the outer edge of the carrier tape. The outer circumferential surface of the second roller faces the outer circumferential surface of the small-diameter portion of the first roller. The large-diameter portion of the first roller constitutes the supporting member.
Accordingly, the supporting member is formed as an integral part to the first roller. Thus, the structure is simpler than in cases where the roller and supporting member are formed as separate parts. Furthermore, regardless of the assembly precision of the rollers, the difference in height positions between the outer circumferential surface of the small-diameter portion of the first roller (which is the pressure-holding position of the side edge portion of the carrier tape) and the outer circumferential surface of the large-diameter portion of the first roller (which is the holding position of the center side of the carrier tape) can be accurately maintained.
Furthermore, a feeding movement of the carrier tape is imparted by the first roller using its small-diameter portion (which constitutes the pressure-holding position) and its large-diameter portion (which constitutes the supporting member). Here, however, the small-diameter portion and large-diameter portion are integral and rotate together; accordingly, the feeding movement created by the large-diameter portion is greater than the feeding movement created by the small-diameter portion. In other words, the feeding movement of the center side of the carrier tape is greater than the feeding movement of the side edge portion of the carrier tape
Sato Koji
Shiozawa Shigeru
Takahashi Koichi
Kabushiki Kaisha Shinkawa
Koda & Androlia
Mansen Michael R.
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