U.S. patent application number 10/682788 was filed with the patent office on 2005-04-14 for tray with flat bottom reference surface.
Invention is credited to Bradley, Scott C., Pylant, James D..
Application Number | 20050077205 10/682788 |
Document ID | / |
Family ID | 34422612 |
Filed Date | 2005-04-14 |
United States Patent
Application |
20050077205 |
Kind Code |
A1 |
Pylant, James D. ; et
al. |
April 14, 2005 |
Tray with flat bottom reference surface
Abstract
A molded component tray includes a component housing portion
having a plurality of component pockets. 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 flange bottom surface includes recessed
areas positioned in alignment with mold ejector pins which may
contact the flange bottom surface, and alternatively in alignment
with mold ejector pin marks on the flange top surface. The depth of
the recesses is greater than the height burrs left by the ejector
pins, thereby leaving the tray bottom surface free of burrs caused
by ejector pins. Alternatively, when one tray is stacked on top of
another, the recesses in the bottom of an upper tray can be
positioned to allow clearance for ejector pin marks on the top of
the flange of a lower tray.
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: |
34422612 |
Appl. No.: |
10/682788 |
Filed: |
October 8, 2003 |
Current U.S.
Class: |
206/710 |
Current CPC
Class: |
H01L 21/67333 20130101;
B65D 1/36 20130101 |
Class at
Publication: |
206/710 |
International
Class: |
B65D 085/30 |
Claims
1. A tray comprising: a molded tray including a component housing
having a plurality of pockets for holding components; and a tray
surface having a plurality of recesses, each recess for recessing a
burr on a bottom surface of said recess below said tray
surface.
2. A tray as recited in claim 1 wherein said burr is caused by
contact of a mold ejector pin with said bottom surface.
3. A tray as recited in claim 1 wherein said tray has a flange, and
said tray surface includes a flange surface.
4. A tray as recited in claim 3 wherein said tray surface includes
a flange top surface.
5. A tray as recited in claim 3 wherein said tray surface includes
a flange bottom surface.
6. A tray comprising: a tray for holding a plurality of
semiconductor devices, said tray including a component housing
having a plurality of pockets for holding said semiconductor
devices; and a flange surrounding said housing, said flange having
a flange surface with a plurality of recesses formed therein for
providing clearance for a burr on a mating surface for contacting
said flange surface.
7. A tray as recited in claim 6 wherein said flange surface is a
flange bottom surface, and said mating surface is a flange top
surface of a second tray upon which said tray is to be placed.
8. A tray as recited in claim 7 wherein said burr is caused by
contact of a mold ejector pin with said flange top surface of said
second tray.
9. A method of tray manufacture comprising: forming a plurality of
recesses in a tray for holding semiconductors devices using a mold;
and applying a mold ejector pin to a recess bottom surface of a
said recess for ejecting said tray from said mold.
10. A method as recited in claim 9 wherein said tray includes a
flange, and at least one of said recesses is in a flange top
surface.
11. A method as recited in claim 10 wherein said tray includes a
flange, and at least one of said recesses is in a flange bottom
surface.
Description
RELATED APPLICATIONS
[0001] This application is related to U.S. Application entitled
Bare Die Tray With Flat Datum Surface filed on the same date as
this application, bearing attorney reference 0678100301344 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 pockets. 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 on 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 the burrs are not consistent from one tray to another, the
height of surface 20 is 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 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
recessed areas for contact with mold ejector pins so as to avoid
uncertain contacts due to burrs, and therefore provides a flat
datum surface.
[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 stacking of trays
and calibration.
[0012] In one embodiment of the present invention, a molded
component tray includes a component housing portion having a
plurality of component pockets. 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 flange bottom surface includes recessed areas
positioned in alignment with mold ejector pins which may contact
the flange bottom surface, and alternatively in alignment with mold
ejector pin marks on the flange top surface. The depth of the
recesses is greater than the height of burrs left by the ejector
pins, thereby leaving the tray bottom surface free of burrs caused
by ejector pins. Alternatively, when one tray is stacked on top of
another, the recesses in the bottom of an upper tray can be
positioned to allow clearance for ejector pin marks on the top of
the flange of a lower tray.
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 the tray of FIG. 2A
according to the present invention;
[0017] FIG. 2C is an enlargened section view from FIG. 2B;
[0018] FIG. 3 shows two trays stacked, with recesses in the tray
bottom flange surface; and
[0019] FIG. 4 shows two trays stacked, with recesses in the flange
top surface.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] 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.
[0021] 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. The component pockets 26 are for holding
small components, such as semiconductor devices. 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 shows burrs/blemishes 36, which may or may not
occur on the surface 32. The burrs/blemishes 36 shown in FIG. 2A
raised from the top surface 32 may be due to 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 pressure of mold ejector
pins.
[0022] According to the present invention, recesses 40 are formed
along the bottom surface 34 to be in alignment with the
burrs/blemishes 36 and/or 38, which in a particular embodiment are
caused by ejector pins used for removing the tray from a mold. For
example, if the mold is designed for ejector pins to push on the
bottom of a tray for the purpose of ejecting the tray from the
mold, the recesses are configured to be in alignment with the
ejector pins and at a diameter somewhat greater than the pins so
that the pins make their mark on the bottom of the recesses 40. The
depth of the recess need only be in excess of the height of the
burr/mark 38 left by the ejector pins.
[0023] In the event that burrs exist on the top surface 32, such as
ejector pins used to press on the top surface 32 of the tray, then
the recesses 40 in the bottom surface are designed to provide
corresponding clearance for the burrs 36 on the top surface, so as
to allow a flat mating surface 32 for a tray bottom surface 34 in
the event that the trays are stacked.
[0024] A recess 40 can therefor provide a recess bottom surface
upon which to apply an ejector pin, or/and the recess 40 can serve
to provide clearance for a burr/mark on a mating top surface when
trays are stacked.
[0025] FIG. 2C is an enlargened section A taken from FIG. 2B to
show recesses and burrs more clearly.
[0026] The recesses 40 of FIG. 2B are shown as an example of the
concept of the present invention. The invention also includes
recesses of other configurations and positions to allow clearance
for burrs/blemishes in any mating surface that the tray may be set
upon. For example, in the event that trays are stacked, a recess in
surface 34 may be included to allow clearance for any raised mark
in the surface 32 of a lower tray. A raised mark for example, could
be caused by an ejector pin, or it could for example be a company
symbol/logo or a part number, etc.
[0027] As a further alternate embodiment, one or more recesses can
be placed in the top surface 32, to provide recess bottom surfaces
for ejector pins that may be applied to the top surface 32, or as a
recess to provide clearance for an ejector pin mark on a tray
bottom surface when trays are stacked. It should be noted however,
that placing a recess only on the top surface does not provide a
flat reference surface on the bottom of a tray, which would be a
problem for the bottom tray of a stack if there are marks on the
bottom surface.
[0028] FIG. 3 is a cross sectional view of two trays 42 and 44
stacked one upon the other, and illustrates the use of recesses 46
to achieve a flat bottom reference surface 48, for example on tray
42 to sit on the top surface 50 of tray 44, and the flat bottom
surface 48 on tray 44 to sit on a base surface 54. FIG. 3 shows how
the recesses 46 provide clearance for burrs 56 on the top surface
50 of tray 44, as well as provide recess bottom surfaces 58 for the
application where contact with ejector pins causes burrs 60.
[0029] FIG. 4 shows two trays 62 and 64 stacked, wherein the trays
have recesses 66 in the top flange surface 68 to provide a recess
bottom surface 70 for receiving ejector pins that leave a mark/burr
72.
[0030] The present invention also includes trays with recesses in
both the top and bottom surfaces for providing clearance for any
type of surface burrs/blemishes, such as ejector pin marks or
raised lettering, logos, etc. in a mating 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.
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