Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – For plural devices
Reexamination Certificate
2003-04-29
2004-01-27
Chambliss, Alonzo (Department: 2827)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
For plural devices
C257S727000, C257S730000, C257S773000, C206S711000
Reexamination Certificate
active
06683378
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to semiconductor packaging. More particularly, this invention relates to a method and to a system for singulating semiconductor components contained on a substrate.
Semiconductor components, such as packages, multi chip modules, printed circuit boards and interconnects are typically fabricated on a substrate which contains multiple components. The substrate can comprise a panel containing one or more rows of components, or one or more arrays of components in a matrix of rows and columns. Following the fabrication process the substrate is singulated into individual components.
BGA packages and chip scale packages, for example, can be fabricated on a substrate made of a circuit board material, such as bismaleimide triazine (BT). Typically, the singulation process is performed by cutting the substrate, such that each component includes a “component substrate” formed by a portion of the substrate. One method for cutting the substrate uses diamond tipped saw blades, similar to the blades used to dice semiconductor wafers into individual dice. In addition, the substrate can include locator openings for receiving locator pins, which are adapted to align the substrate to the saw blades during the sawing step of the singulation process.
Referring to
FIGS. 1A and 1B
, a prior art substrate
10
A made for fabricating semiconductor components
12
is illustrated. As shown in
FIG. 1A
, the substrate
10
A is a panel (or strip) of material similar in function to a metal leadframe. In this example, the substrate
10
A comprises a circuit board material, and the components
12
comprise BGA packages arranged in a single row on the substrate
10
A. However, the components
12
, rather than being BGA packages, can comprise other electronic elements made with semiconductor dice, such as chip scale packages, multi chip modules or printed circuit boards. The components
12
can also comprise interconnects for electrically engaging semiconductor dice. In addition, the components
12
can be arranged in more than one row (e.g., two rows, three rows etc.).
As shown in
FIG. 1B
, the components
12
include an encapsulant
14
which encapsulates a semiconductor die (not shown) bonded to a first side
18
of the substrate
10
A. In addition, the components
12
include external contacts
16
, such as solder balls in a grid array, formed on a second side
20
of the substrate
10
A in electrical communication with the die. The substrate
10
A also includes locator openings
22
formed along the opposing longitudinal edges of the substrate
10
A. The locator openings
22
facilitate handling of the substrate
10
A by automated equipment, such as conveyors, loaders and magazines. The locator openings
22
also function to align the substrate
10
A, and the components
12
, on various process equipment during different fabrication processes such as singulation, die attach and wire bonding.
Referring to
FIGS. 1C and 1D
, a prior art matrix substrate
10
B for fabricating the semiconductor components
12
is illustrated. The substrate
10
B is substantially similar in construction to the substrate
10
A described above. However, in this case the substrate
10
B, following a singulation step, includes separate arrays
27
, each of which includes multiple components
12
arranged in a matrix of rows and columns. As with the substrate
10
A, the substrate
10
B includes locator openings
22
that facilitate handling and alignment of the substrate
10
B during fabrication of the components
12
. As another alternative, the substrate can comprise a panel that contains a single matrix of components
12
rather than multiple arrays.
Referring to
FIGS. 2A and 2B
, a prior art system
23
for singulating the substrate
10
A is illustrated. The system
23
includes a nest
24
for supporting the substrate
10
A, a clamp assembly
25
for clamping the substrate
10
A on the nest
24
, and a sawing base
30
for holding the nest
24
during a sawing step of the singulation process.
As shown in
FIG. 2B
, the system
23
also includes one or more saw blades
28
configured to saw the substrate
10
A into the separate components
12
. The saw blades
28
rotate at high rpms, as indicated by rotational arrow
31
, and are also movable in the z-direction as indicated by z-direction arrow
34
. The sawing base
30
is moveable in an axial directions (e.g., x-direction) as indicated by axial direction arrow
37
. The saw blades
28
are configured to saw across the lateral axis, or along the longitudinal axis of the substrate
10
A, as the sawing base
30
moves the substrate
10
A in axial directions as required. The sawing base
30
can also be rotated about it's longitudinal axis (theta rotation) for positioning the substrate
10
A for lateral or longitudinal sawing. Such a prior art system is manufactured by Intercon Tools, Inc. of Morgan Hill, Calif.
As shown in
FIG. 2A
, the nest
24
includes locator pins
26
which are placed through the locator openings
22
(
FIG. 1A
) in the substrate
10
A. The locator openings
22
align the substrate
10
A on the nest
24
. As also shown in
FIG. 2A
, the substrate
10
A is initially placed on the locator pins
26
, and then clamped to the nest
24
using the clamp assembly
25
.
As shown in
FIG. 2B
, the nest
24
is then placed on the sawing base
30
, and the clamp assembly
25
is removed. The sawing base
30
includes mounting studs
36
that mate with mounting openings
38
on the nest
24
, and also one or more vacuum conduits (not shown) for holding the nest
24
on the sawing base
30
. The sawing base
30
also includes a pedestal
39
, and a vacuum conduit
40
, configured to apply a vacuum for holding the substrate
10
A on the nest
24
once the clamp assembly
25
is removed. With the substrate
10
A held on the nest
24
, and the nest
24
held on the sawing base
30
, the sawing step is performed by moving the sawing base
30
in the axial direction
37
, such that the saw blades
28
saw across the width, or the length, of the substrate
10
A as required.
One shortcoming of this prior art system
23
is that the locator pins
26
sometimes collect sawing scrap
32
(
FIG. 2C
) during the sawing step. The scrap
32
(
FIG. 2C
) can include pieces of the substrate
10
A, as well as other debris from the sawing step. As the saw blades
28
rotate in close proximity to the locator pins
26
, the scrap
32
(
FIG. 2C
) can come in contact with the rotating saw blades
28
causing bending, and in some cases breakage of the saw blades
28
. As is apparent, the damaged saw blades
28
are expensive to replace. In addition, replacement of the saw blades
28
requires that the sawing equipment be shut down, which causes even more costly production delays.
Besides damaging the saw blades
28
the scrap
32
can also cause problems with loading of the substrate
10
A into the nest
24
, and with unloading of the singulated components
12
from the nest
24
. These problems can also cause production delays, and require operators of the system
23
to manually remove the sawing scrap
32
from the locator pins
26
.
The present invention is directed to a method and to a system for singulating semiconductor components in which locator pins are eliminated from the sawing step. Specifically, the invention includes a pre-stage alignment step in which the substrate is aligned for the sawing step. Although locator pins are used during the pre-stage alignment step, the locator pins are eliminated from the nest, such that scrap does not collect on the locator pins during the sawing step, and damage to the saw blades is reduced.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved method and system for singulating semiconductor components are provided. Also provided are an improved sawing nest for semiconductor components, and improved semiconductor components fabricated using the method and the system.
The method includes the step of providing a substrate containing the components, and
Chapman Gregory M.
Wing Jason C.
Chambliss Alonzo
Gratton Stephen A.
Micro)n Technology, Inc.
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