One piece flatpack chip carrier

A one piece carrier for flatpack chips capable of accommodating chips of varying size. The carrier includes a pair of cantilever arms each having a tapered head for holding chips of varying thicknesses. The arms extend into the carrier's central aperture, one from the top and one from the bottom side of the aperture. Longitudinally offset stops are mounted on the arms to both laterally and longitudinally stabilize a small chip whose length is insufficient to reach the conventional stops mounted on the top and bottom sides of the central aperture. A recess is provided in the lateral sides of the central aperture to accommodate motion of the cantilever arms so that chips of varying widths may be held between the heads of the arms up to the width of the central aperture. A step of lower elevation is formed in the body of the carrier between the lead support channels adjacent the lateral sides of the central aperture to accommodate the formed leads of a chip.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to the field of flatpack integrated chip carriers. 
2. Brief Description of the Prior Art 
There are many forms of one piece flatpack chip carriers. See e.g., Ralstin 
U.S. Pat. No. 4,435,724 assigned to Wells Electronics, Inc., Alemanni U.S. 
Pat. No. 4,379,505 assigned to Gibson-Egan Co., Tems U.S. Pat. No. 
3,652,974 assigned to Milcross Control, Inc. (aka Milton Ross), Barnes 
U.S. Pat. No. 3,529,277, and Suverkropp et al. U.S. Pat. No. 3,471,865 
assigned to Signetics Corp. See also Morton, Jr. U.S. Pat. No. 4,444,309 
assigned to Bourns, Inc., a leadless chip carrier. 
Common to these carriers is a design that is intended to accommodate a 
specific size chip. However, chips come in many different widths, lengths 
and thicknesses. Thus they are loaded into many different configuration 
carriers by their manufactures. These different carrier configurations 
represent a barrier to automatic assembly operations. 
SUMMARY OF THE INVENTION 
The invention comprises a one piece carrier suitable for automatic assembly 
processes which accommodates flatpack chips of varying size. The one piece 
carrier has a body portion upon which are mounted a plurality of lateral 
side channels to support the leads of a flatpack chip. A central aperture 
formed in the body portion has top, bottom and right and left sides. The 
carrier includes a pair of cantilever arms each having a tapered head for 
holding a chip. The arms extend into the carrier's central aperture, one 
from the top and one from the bottom side of the aperture. Longitudinally 
offset stops are mounted on the arms to both laterally and longitudinally 
stabalize a small chip whose length is insufficient to reach the 
conventional stops mounted on the top and bottom sides of the central 
aperture. A recess is provided in the lateral sides of the central 
aperture to accommodate motion of the cantilever arms so that chips of 
varying widths may be held between the heads of the arms up to the width 
of the central aperture. A step of lower elevation is formed in the body 
of the carrier between the lead support channels adjacent the lateral 
sides of the central aperture to accommodate the formed leads of a chip.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a perspective view of the preferred embodiment of the present 
invention. It is comprised of a body portion 10 having mounted thereon a 
series of lateral channels 12 extending from a central aperture 14 for 
supporting the leads of a flatpack chip (not shown). The outer ends of the 
four outer channels have closing walls 16 which permit the carriers to be 
stacked and slid relative to one another without the channels becoming 
stuck. (In most standard carriers, the underside of the carrier has a 
grove adjacent one side into which the narrow wall of a channel can fit 
and become stuck.) 
The central aperture has four sides: top 18, bottom 20, left 22 and right 
24. Mounted on the top side and extending into the aperture is a stop 26. 
Mounted on the bottom side is a similar stop 28. These two stops provide 
longitudinal support for most chips. Support for short chips will be 
discussed momentarily. Also mounted on the top side of the central 
aperture and spaced from the center of the side by a predetemined distance 
is a resilient cantilever arm 30. A similar arm 32 is mounted on the 
bottom side a space an equal an opposite distance from the center of the 
bottom side. Each arm extends into the central aperture a distance 
sufficient for its second end (34 and 36) to lie beyond the centerline 
between the centers of the left and right sides of the central aperture. 
Mounted on these arm ends are tapered heads 38 and 40. Preferrably, the 
ends 34 and 36 of the cantilever arms are aligned with the wall of a 
channel so that the tpaered heads do not to interfere with the leads of a 
of a flatpack chip. Adjacent these ends, recesses 42 and 44 are formed in 
the right and left sides respectively. This permits the resilient 
cantilever arms greater freedom of motion away from the center of the 
aperture. The arms may be withdrawn from a chip for loading and unloading 
the chip. Further, the extra space permits large chips to be loaded into 
the carrier. If the recesses are made sufficiently large, chips whose 
widths are as wide as the central aperture itself may be loaded into the 
carrier. 
FIG. 2 shows a top plan view of the one piece carrier of the preferred 
embodiment. This figure shows essentially the same elements as shown in 
FIG. 1, and to the extent they were described in FIG. 1, they will not be 
descibed further here. Additional features not discussed in relation to 
FIG. 1 are stops 46 and 48 mounted on the interior of arms 30 and 32 
respectively, facing the center of the central aperture. The stops provide 
lateral support for a chip when mounted in the carrier between arms 30 and 
32. Due to the fact that the arms project from opposite walls, these stops 
are longitudinally offset from one another. Thus, should a chip be of 
insufficient length for it to rest on stops 26 and 28 mounted on the top 
and bottom sides of the central aperture, the offset itself will provide 
not only lateral, but also longitudinal support. This feature is important 
in that several assembly steps take place while the chip remains in the 
carrier. One such step is the stamping of identification material on the 
body of the chip. Without such longitudinal support, the chip would wobble 
in the carrier, bending the leads to an impermissible extent. 
Also show in FIG. 2 are steps 50 and 52 extending from the left and right 
sides of the central aperture respectively a short, predetermined distance 
sufficient to accommodate the leads of a chip after they have been formed. 
Typically, the chip, before final assembly to circuit board, is removed 
from the carrier and the leads are formed and tinned. The forming process 
bends the leads down a short distance and cuts them off. Thus steps 50 and 
52 are of lower elevation than rest of the body portion between the 
channels 12 to accommodate the bent leads. The length of the steps are 
such as to accommodate the trimmed leads. 
FIG. 3 shows one of the tapered heads, 38. The heads are mounted on the 
ends of the arms and extend upwards to the top of the channels 12. Each 
head has an inwardly facing tapered edge 54, whose wide portion comprises 
the top of the head and whose narrow portion cmprises the bottom of the 
head, which is mounted on the arm. The head in the preferred embodiment is 
formed as a one piece unit with the cantilever arms. 
The taper of the heads permits the loading of chips of varying thicknesses 
into the one piece carrier. The heads are designed to be taller than the 
thickest chip to be mounted in the carrier. Thus, when mounted, the chip 
spreads the resilient cantilevered arms apart and contact the heads along 
their tapered edges 54. The tapered edge of the heads tends to force the 
chip down into chip against the stops 46 and 48, and if the chip is long 
enough, stops 26 and 28. 
FIG. 4 shows a detail of a portion of arm 32 and head 40 of FIG. 2. Near 
the end of each arm, the arm is bent inwardly by a small angle, which in 
the preferred embodiment is 6 degrees 18 minutes. This is the same angle 
by which the resilient arms are spread away from the center of the central 
aperture by a chip mounted therein, when the chip is of a "standard" 
thickness. This permits the face of the tapered edge to contact the chip 
flat. The angle of the preferred embodiment may of course be varied as 
necessary by those skilled in the art to accomplish the same purpose. 
FIG. 5 is a cross-sectional view along 5--5 of FIG. 2. The view shows the 
walls 13 of the channels 12, which as aforementioned, provide support for 
the leads of the flatpack chip. Cuts 56 and 58 in two of these wall mark 
the edges of recess 42, which extends from the body portion 10 to the top 
of the channel walls 13. Step 52 is also shown as a lower elevational 
between channel walls 13. Stops 26 and 28 are also shown. The tops 60 of 
these stops are even with the top 62 of the body portion 10 between 
channels 12. 
The Figure also shows cantilever arm 30, head 38 with facing tapered edge 
54 and stop 46 mounted on the interior of arm 30 facing the center of the 
central aperture 14. The top 64 of this stop is even with the top of the 
stops 26, 28 and 48, and is also even with the top of the body portion of 
the chip carrier between channels 12. The stop also extends a short 
distance above arm 30. This permits the pins of an automatic assembly 
device to enter the chip carrier from below, contact the cantilever arm, 
and push it away from the center of the central aperture without 
interference from a flatpack chip sitting atop stop 46. 
This feature is also shown in FIG. 6, a cross-sectional view along 6--6 of 
FIG. 2, wherein the height of stops 46 and 48 extends their tops above 
arms 30 and 32. Stop 26 is also shown. Shown also in the figure is head 40 
mounted on the end of arm 32 with tapered edge 66 facing inwards toward 
the center of central aperture 14. The primary feature shown in this 
Figure are steps 50 and 52 which are lower elevational areas formed in the 
body portion 10 of the carrier. The steps extend a short distance form the 
left and right sides of the central aperture, the distance being 
sufficient to accommodate trimmed, bent, formed leads. 
Finally, FIG. 7 shows a cross-sectional view along 7--7 of FIG. 2. This 
Figure shows similar features as that of FIG. 6, but this time shows head 
38 mounted on arm 30. Also shown are steps 50 and 52 as well a stop 26. 
This completes a discussion of the preferred embodiment. An alternative 
embodiment is shown in FIGS. 8 through 10 where the only additional 
feature is the addition of two forward stops 70 and 72 mounted on the ends 
of arms 30 and 32 respectively. The forward stops are angled into the 
center of the aperture as can be seen from FIG. 9 and are of the same 
height as the arms, as can be seen from FIG. 10. Because these forward 
stops are lower than stops 26 and 28, they normally will not contact a 
chip. However, when a chip is insufficently long to contact the stops 26 
and 28, these stops act an auxillially longitudinal support mechanisms to 
limit the degree of wobble when a chip is placed under pressure, such as 
when it is stamped. 
The specifcation of the elements of the preferred embodiments should not be 
taken as a limitation on the scope of the appended claims, wherein