U.S. patent application number 10/682789 was filed with the patent office on 2005-04-14 for bare die tray with flat datum surface.
Invention is credited to Bradley, Scott C., Pylant, James D..
Application Number | 20050077206 10/682789 |
Document ID | / |
Family ID | 34422613 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050077206 |
Kind Code |
A1 |
Pylant, James D. ; et
al. |
April 14, 2005 |
Bare die tray with flat datum surface
Abstract
In one embodiment of the present invention, a component tray
includes a component housing portion having a plurality of
component pockets, with each pocket opening to a component housing
top surface. The tray has a flange around the component housing
portion defining a perimeter of the tray. A flange top surface in
one embodiment is below the component housing top surface. A
plurality of bosses extend downward from a flange bottom surface,
and are designed to be positioned in dis-alignment with burrs
caused by contact of mold ejector pins with flange bottom and top
surfaces. The height of the bosses is designed to exceed the height
of burrs, and therefore avoid contact of the burrs with any surface
upon which the tray is set. A bottom cavity provides clearance for
a tray component housing.
Inventors: |
Pylant, James D.; (Temecula,
CA) ; Bradley, Scott C.; (Carlsbad, CA) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
2475 HANOVER STREET
PALO ALTO
CA
94304-1114
US
|
Family ID: |
34422613 |
Appl. No.: |
10/682789 |
Filed: |
October 8, 2003 |
Current U.S.
Class: |
206/710 |
Current CPC
Class: |
B65D 1/36 20130101; H01L
21/67333 20130101 |
Class at
Publication: |
206/710 |
International
Class: |
B65D 085/30 |
Claims
1. A component tray comprising: a component pocket housing having a
plurality of component pockets opening to a housing top surface; a
tray surface having a plurality of bosses formed thereon and
extending from said tray surface, wherein said bosses are
positioned and configured to have a height sufficient to prevent a
burr on said tray surface from contacting another surface in
contact with said tray.
2. A tray as recited in claim 1 wherein said tray surface is on a
flange extending from said component pocket housing.
3. A tray as recited in claim 2 wherein said tray surface is on a
bottom of said flange.
4. A tray as recited in claim 3 wherein said tray surface is on a
top surface of said flange.
5. A tray as recited in claim 3 wherein said another surface is a
top surface of a flange of another tray.
6. A tray as recited in claim 4 wherein said another surface is a
bottom surface of a flange of another tray.
7. A tray as recited in claim 2 wherein said tray is formed in a
mold, and said burrs are formed by contact of mold ejector pins
with said flange.
8. A tray as recited in claim 7 wherein said bosses provide
reference surfaces allowing accurate calibration of said housing
top surface.
9. A component tray comprising: a component pocket housing having a
plurality of component pockets opening to a housing top surface;
and a tray surface having a plurality of bosses formed thereon and
extending from said tray surface, wherein said bosses are for
preventing burrs on another surface making contact with said
tray.
10. A tray as recited in claim 9 wherein said tray surface is on a
flange extending from said component pocket housing.
11. A tray as recited in claim 10 wherein said tray surface is on a
bottom of said flange.
12. A tray as recited in claim 10 wherein said tray surface is on a
top of said flange.
13. A tray as recited in claim 10 wherein said another surface is a
top surface of a flange of a second tray.
14. A tray as recited in claim 13 wherein said burr is caused by
contact of a mold ejector pin with said tray surface of said flange
of said second tray.
15. A tray as recited in claim 13 wherein said second tray is
formed in a mold and said burrs are formed by contact of mold
ejector pins with said flange.
16. A method of tray manufacture comprising: forming a plurality of
bosses on a surface of a tray flange using a mold, wherein said
tray is for holding a plurality of semiconductor devices; and
applying a mold ejector pin to said flange to eject said tray from
said mold.
17. A method as recited in claim 16 wherein said bosses are formed
on a bottom surface as said flange, and said mold ejector pins
contact a top surface of said flange, and wherein said pins are in
dis-alignment with said bosses.
18. A method as recited in claim 16 where said bosses are formed on
a bottom surface of said flange, and said ejector pins contact a
bottom surface of said flange.
Description
RELATED APPLICATIONS
[0001] This application is related to U.S. application entitled
Tray With Flat Bottom Reference Surface filed on the same date as
this application, having attorney reference 0067810/0303882 which
is expressly incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to trays for use in carrying
components such as semiconductors, and more particularly to a tray
having flat datum surfaces and configured to avoid calibration
variations due to mold injector pin burrs imposed on the tray
during manufacture.
[0004] 2. Description of the Related Art
[0005] Small components such as semiconductors are often stored or
shipped in molded plastic trays similar to tray 10 shown in FIGS.
1A and 1B. In the molding production operation, ejector pins are
used to push/eject the tray from the mold casing. Burrs are caused
from molten plastic filling the circumferential gap between the
ejector pin and the ejector pin hole. Slight protrusions can also
occur if the ejector pin is not level with the part surface. Part
ejection is a forceful process, and the pressure of the pins on the
tray leaves burrs/marks/blemishes on the tray surfaces. These burrs
cause variations in the effective tray thickness and as a result
trays cannot be stacked with a consistent height or degree of
flatness. The burrs cause errors in calibration of automated tray
handling equipment, and equipment for picking and placing
components in tray component packets. Removal of burrs would
involve additional and expensive machining or manual processes, and
generally is not practical.
[0006] FIG. 1A is a perspective top view of a prior art tray 10
showing ejector pin marks/burrs 12 left after ejecting the tray 10
from a mold. FIG. 1B is a perspective bottom view of the tray 10
showing ejector pin marks 14. For stacking of trays such as tray 10
and for calibration of automated tray handling equipment for use in
handling trays of the design shown in FIGS. 1A and 1B, it is
necessary to use surfaces 16 and 18 as reference surfaces. The
burrs 12 and 14 cause problems in the calibration. For example,
since burrs 14 would not be consistent from one tray to another,
the height of surface 20 would also be less certain from one tray
to another, and from one side of a tray 10 to another side of the
tray. These distorted/inaccurate reference surfaces limit the
ability of automatic machines to accurately pick and place
components in the tray. The burrs 12 and/or 14 also cause an
uncertainty in the height and straightness of a stack of trays 10,
causing problems with automatic stack handling equipment, as well
as problems with shipping containers and clips.
SUMMARY
[0007] It is an advantage of this invention in that it provides a
component tray that has improved reference surfaces.
[0008] It is a further advantage in this invention in that it adds
bosses to a bottom surface of a tray so as to avoid uncertain
contacts due to burrs.
[0009] It is a still further advantage of this invention in
providing a tray that in use maximizes the accuracy of calibration
of automated equipment.
[0010] It is another advantage of this invention in providing a
tray that can be stacked accurately.
[0011] It is another advantage of this invention in providing a
tray wherein ejector pin blemishes do not affect stacks and
calibration.
[0012] In one embodiment of the present invention, a component tray
includes a component housing portion having a plurality of
component pockets, with each pocket opening to a component housing
top surface. The tray has a contacting surface which makes contact
with a mating surface upon which the tray is placed, such as an
equipment handling base, or a contacting surface of another tray if
trays are stacked. In one embodiment the contacting surface is on a
flange surrounding the component housing portion defining a
perimeter of the tray. A flange top surface in one embodiment is
below the component housing top surface. A plurality of bosses
extend downward from a flange bottom surface, and are designed to
be positioned in dis-alignment with burrs caused by contact of mold
ejector pins with flange bottom and top surfaces. The height of the
bosses is designed to exceed the height of burrs, so as to avoid
contact of the burrs with any surface upon which the tray is set. A
bottom cavity in each tray provides clearance for a tray component
housing of another tray upon which it is stacked.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1A is a perspective top view of a prior art tray;
[0014] FIG. 1B is a perspective bottom view of the prior art tray
of FIG. 1A;
[0015] FIG. 2A is a perspective top view of a tray according to the
present invention;
[0016] FIG. 2B is a perspective bottom view of a tray according to
the present invention.
[0017] FIG. 3A is a top perspective view of two trays of the
present invention in position to be stacked;
[0018] FIG. 3B is a bottom perspective view of the trays of FIG.
3A;
[0019] FIG. 4 is a planar view of a tray illustrating more clearly
the principle of the present invention;
[0020] FIG. 5 shows three trays stacked; and
[0021] FIG. 6 illustrates using bosses attached to a base to
determine an accurate reference surface for picking and placing
components in tray pockets.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] While the present invention will be described herein with
reference to particular embodiments thereof, a latitude of
modifications, various changes and substitutions are intended, and
it will be appreciated that in some instances some features of the
invention will be employed without a corresponding use of other
features without departing from the spirit and scope of the
invention as described with respect to the preferred embodiments
set forth herein.
[0023] Referring now to FIGS. 2A and 2B, a component tray 22 is
shown that has been formed in a mold. The tray 22 has a component
housing portion 24 containing a plurality of component pockets 26
opening to top surface 28. A flange 30 extends around the housing
portion 24, defining the perimeter of the tray 22. The flange 30
has a flange top surface 32, and a bottom surface 34 shown in FIG.
2B. The flange alternatively can be of other configurations, for
example the flange could extend less than completely around the
housing, or could be in segments, such as only on two opposite
sides of the housing. The flange top surface 32 can alternatively
also be of different heights, including above, below or equal to
the top surface 28 of the housing 24. FIG. 2A illustrates a
particular embodiment wherein surface burrs/blemishes 36 are shown
on the top surface 32 caused by mold ejector pins when the molded
tray 22 is ejected from the mold. FIG. 2B is a bottom perspective
view of the tray 22 of FIG. 2A, and also shows burrs/blemishes 38
formed as a result of the pressure of mold ejector pins on the
flange bottom surface 34. Although FIGS. 2A and 2B show burrs on
both the top and bottom flange surfaces, the spirit of the present
invention also includes trays having burrs on just a top or bottom
surface.
[0024] According to one embodiment of the present invention, the
tray 22 has bosses 40 extending from the flange bottom surface 34
to a height that is high enough to prevent the burrs 38 from
contacting a surface on which the tray is placed. More generally,
the present invention includes bosses on any surface for preventing
contact of burrs/blemishes with any surface. In one embodiment, the
bosses are greater than twice an expected height of the
burrs/blemishes so that when the trays are stacked, one on another,
any burrs facing each other do not interfere with each other i.e.
in the case of burrs on the flange bottom surface of an upper tray
in a stack and any burrs on the flange top surface of a bottom
tray. This is shown, and will be described more clearly in
reference to FIG. 5. In this way, the bosses solve the problem of
the burrs/ejector pin marks interfering in stacking and calibration
operations. In the various figures, only a few of the bosses and
burrs are labeled with numbers for ease of illustration. Generally,
a boss is shown on the flange bottom surface 34 between every two
burrs. The present invention, however, also includes other
arrangements including fewer or greater numbers of bosses, and/or
bosses of other configurations. The number of bosses required is
only a sufficient number placed so as to assure tray stability when
placed in contact with a mating surface.
[0025] FIGS. 3A and 3B illustrate two trays of the present
invention placed one over the other as in preparation for stacking.
FIG. 3A shows the fact that a plurality of trays 22
processed/molded by the same mold or molds of the same design, will
have ejector pin marks/burrs 36 and/or 38 in alignment with each
other as indicated by line 44 (FIG. 3A) when the trays 22 are
placed in an aligned, stacked position as shown. FIG. 3B is a
bottom view of the two trays of FIG. 3A, and shows bosses 40,
designed as described above in one embodiment so as to have a
height that is greater than twice the expected or actual height of
the ejector pin marks/burrs 36 and 38 so that when the trays are
stacked, the two burrs facing each other, one burr 36 on the flange
top surface and one burr 38 on the flange bottom surface, do not
touch each other. This can be seen clearly in reference to FIG. 5.
In the case where burrs are only on the top or bottom, but not
both, the required minimum height of the bosses need only be
greater than the height of the burrs on the single surface.
[0026] Line 48 indicates that the bosses 40 of the two trays 22 are
in alignment. According to the present invention, the bosses are
positioned so as not to be in alignment with the ejector pin marks
36 or 38. Line 50 indicates the alignment of the ejector pin marks
38. Contact between the two trays is made by contact of the
surfaces 52 of the bosses 40 with the flange top surface 32 (FIG.
3A). In the event that burrs are on both the top and bottom of the
tray, the burrs 36 and 38 of one tray do not make contact with
another tray when stacked because the height of the bosses 40 is
more than the combined height of burrs 36 and 38.
[0027] A planar side view of a tray 54 is shown in FIG. 4 that is
simplified for ease of illustration by showing fewer bosses and
marks. The present invention, however, includes any number of burrs
and bosses in any configuration wherein the bosses provide a
contact surface and prevent the contact of burrs with surfaces on
which the tray is placed. The tray 54 according to the present
invention has a component pocket housing 56 with a plurality of
component pockets similar to the tray 22 of FIGS. 2 and 3, but for
ease of illustration are not shown in this figure. The housing 56
is surrounded by a tray flange 58, having a flange top surface 60
and a flange bottom surface 62, both surfaces being orthogonal to
the view of FIG. 4. For illustration, three burrs/marks 64 are
shown made by ejector pin contact with the flange top surface 60,
and three ejector pin marks/burrs 66 are shown as made by ejector
pin contact with the flange bottom surface 62. The marks 64 on the
top surface 60 may be in alignment with the marks 66 on the bottom
surface 62 as indicated by line 68. Other configurations wherein
the burrs are not in alignment are also included in the present
invention, wherein bosses are used to avoid contact of the burrs
with surfaces. Four bosses 70 are shown extending from the flange
bottom surface 62. The bosses 70 as shown and according to the
present invention are not aligned with the burrs/marks 64 or 66.
The height "h.sub.1" of the bosses 70 in one embodiment is greater
than twice the anticipated or actual height "h.sub.2" of the
burrs/marks. With this boss height, the bottom surfaces 72 of the
bosses can therefore make contact with a surface on which the tray
is set, including the flange top surface of another tray and
prevent contact of the burrs on the flange bottom surface of a
first tray making contact with a burr on the flange top surface of
a second tray on which the first tray is stacked. This will be
shown more clearly in FIG. 5. In another embodiment, the height of
h.sub.1 of the bosses is simply greater than the height of the
burrs 66 on the flange bottom surface, allowing the tray to be
placed on a flat reference surface 73 without the burrs 66 touching
the surface 73. As noted above, this boss height is also adequate
if there are burrs on only the top or bottom, but not both
surfaces.
[0028] According to a method of the present invention, the tray 54
is set on a base surface 73. The housing surface 75 can be
accurately calibrated due to the accuracy and reproducibility of
the contact between the boss reference surfaces 72 and the base 73.
This is an improvement over the prior art trays wherein the burrs
66 would contact the surface 73. In automated equipment for
example, the base 73 can be a part of the equipment. A tray
according to the present invention allows accurate calibration of
the surface 75 and thereby accurate calibration for handling the
tray 54, and for picking and placing components in component
pockets that open to the surface 75; for example component pockets
26 as shown in FIG. 2A.
[0029] FIG. 5 shows three trays 77 in a stacked arrangement. Note
that each tray 77 generally has a bottom pocket 74 providing
clearance for a component housing 76 of a tray upon which it is
stacked. The bosses 70 are high enough to prohibit contact of the
burrs with a surface, and as shown between the two opposing burrs
64 and 66, and therefore the bosses of an upper tray make contact
with the flange top surface of the tray upon which it is set, and
as a result provide an accurate stack. FIG. 5 also illustrates
placing a stack of trays 79 on a base surface 81, which can be a
surface for example of calibrated tray handling equipment. The
accurate position of the trays as described above due to the
bosses, allows accurate calibration of automated tray handling
equipment.
[0030] FIG. 6 shows an alternate embodiment wherein bosses 78 are
attached to a base 80, such as a part of automated equipment for
tray handling and/or for picking and placing components in
component pockets of a tray 82. Similar to the description above,
the bosses 78 are designed to have a height greater than the height
of otherwise interfering burrs 84 caused by pressure from ejector
pins during a tray molding process. The embodiments described above
all show bosses and burrs on flanges of trays. The present
invention also includes as an alternate embodiment trays with burrs
and bosses at other locations on trays. The present invention also
includes bosses on trays of other configurations. For example, the
tray may or may not have a flange, or the flange area could be of
different heights in relation to the surface 75 of the housing 56
of FIG. 4. These and other combinations/configurations of trays
using bosses to avoid contact of burrs and/or blemishes with
surfaces are included in the spirit of the present invention.
Although the above description describes in detail the use of
bosses to avoid burrs caused by mold ejection pins from contacting
a surface on which a tray is set, or contacting a surface of a
second tray stacked upon a first tray, the present invention also
includes the use of bosses as described above for avoiding contact
of any other kind of surface burr/blemish with a surface. For
example, a burr/blemish could be a raised logo or a part number
formed on a surface.
[0031] While the present invention has been described herein with
reference to particular embodiments thereof, a latitude of
modifications, various changes and substitutions are intended in
the foregoing disclosure, and it will be appreciated that in some
instances some features of the invention will be employed without a
corresponding use of other features without departing from the
spirit and scope of the invention as set forth in the appended
claims.
* * * * *