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MOSIS Packaging And Assembly
Packaging Options
1. Introduction
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In order for an integrated circuit to be useful, it must have physical
connections to the outside world. Designers must consider how their
part will be packaged before they submit a request for fabrication.
MOSIS cannot place a project on a run without knowing how it will be
packaged (even if not packaged by MOSIS).
Designers may select from a list of standard packages provided by
MOSIS, or they may choose to supply their own packages. Users may
request packaged parts, unpackaged parts (loose die) or any mix of
both. MOSIS can also provide access to flip-chip and other advanced
packaging technologies.
After wafers are fabricated by the foundry and tested by MOSIS,
selected wafers are sent to a packager for dicing and assembly. Chips
to be packaged are wire-bonded according to a bonding diagram generated
by MOSIS or provided by the designer.
Packaging options available through MOSIS for MEP designs are listed
in Section 17 of the Educational Program FAQ:
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http://www.mosis.com/Faqs/faq-education.html#17.
Several smaller circuits can be put together in one project. MOSIS
does not currently coordinate the singulation of individual circuits
within one design submission. Possible sources for dicing and
assembly are listed under
Third Party Services.
Contact the assembly vendor to confirm their sawstreet requirements
and die thickness.
2. Die Size
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A chip or die is the actual piece of silicon containing a project. In
addition to the project, the die contains MOSIS overhead and residual
scribe lanes.
Most MOSIS chips are packaged in ceramic or plastic packages, although
other options are available. The chip must fit within the cavity of
the package and meet normal wire bonding requirements. Considerations
include the following:
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Project size
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Buffer and Overhead
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Bare Silicon
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Package Cavity
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Die edge to package cavity spacing
A project's size is defined to be the size of the minimum bounding box
(MBB) containing the design.
To the project's MBB, MOSIS adds buffer to three sides, and buffer and
overhead to the top. The overhead contains critical dimension and
alignment figures, as well as a 6-character MOSIS fabrication ID. For
a design on a dedicated run, MOSIS can often add buffer to all
four sides and not include the overhead at the top.
In the example below, MOSIS adds a 12 micrometer buffer to three
sides, and 42 micrometers total of buffer and overhead to the top.
The width of the scribes will also affect the size of the die. The
saw does not cut to both edges of the scribe, but between the two
edges so there will be some remaining trim. Placement within the
reticle will also affect size as the scribe lanes between reticles are
larger than scribe lanes interior to the reticle.
Example
NOTE: The size of the buffer and overhead varies from one process to
another, and is not drawn to scale.
This allows for necessary project-edge to scribe-lane spacing. Though
the buffer may be as little as 12 micrometers, it can be several
hundred micrometers for reticle-based runs. As a rule of thumb, the
buffer, overhead, and bare silicon will not add so much (beyond the
minimum) that it forces a project into a larger package. For example,
given the project size, minimum overhead, and cavity spacing, if a
design fits a 40-pin DIP, the additional bare silicon will not force
the project into a larger package.
MOSIS stocks packages of varying size with respect to pin count
and cavity size.
Specific
information on any package inventoried by MOSIS is available.
Packagers require a minimum amount of spacing between the die edge and
the package cavity edge. The minimum die edge to cavity edge
spacing is:
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Die Edge to Cavity Edge
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Overall
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Without downbond
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10 Mils (254 micrometers)
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Die size + 20 Mils
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With downbond
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20 Mils (508 micrometers)
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Die size + 40 Mils
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MOSIS packaging vendors may be able to accommodate tighter spacing.
Please send a message to
support@mosis.com for evaluation
of your requirement.
Once the die size and package requirements have been determined,
the pad-to-pin assignments must be considered.
There are three choices:
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You can order unpackaged parts:
WARNING: Final cut die size is always greater than layout size.
Even when your parts will not be packaged by MOSIS, you should inform
us of your packaging plans so that we can consider your requirements
when determining the final cut die size.
MOSIS now offers the
Max Die
Size Update Form to allow you to provide maximum cut die size
constraints to be considered in the reticle planning process.
Please do not be unnecessarily restrictive. Over-sized or under-sized
die may inhibit our ability to include your project on the intended
fabrication run.
Although the above is preferred, an alternative method to specify a
die size constraint for unpackaged parts is to enter a "0" (zero) for
Quantity-Packaged and provide the name of a
Package Available Through MOSIS. The package specified should
have the same cavity size as the actual package to be used for
assembly.
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You can allow MOSIS to assign the pad-to-pin assignments;
By default MOSIS will attempt to generate a best effort bonding
diagram. If MOSIS software is unable to do this automatically MOSIS
will ask you to provide the bonding diagram.
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You can dictate the pad-to-pin assignments.
See Section 12 Bonding Diagrams.
3. Bonding Pad Layout and Placement
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General
MOSIS assembly vendors can bond prototype quantities of parts designed
using all pad design rules referenced below. Customers coordinating
their own assembly should contact their assembly vendor to confirm
bond-ability based on their specific pad layout.
Minimum recommendations for pad layout vary among fabrication and
assembly vendors. The following minimum pad openings and pitch
dimensions should create parts easily bondable by any packaging
vendor. Designers can base their minimum pad opening and pitch
dimensions on the capabilities of the assembly vendor that will be
bonding your parts.
The MOSIS general rule for minimum pad layout for wire bonding is:
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90 µm x 90 µm (3.5 mils x 3.5 mils) glass cut
box over a
100 µm x 100 µm (3.9 mils x 3.9 mils) top metal
box (bonding metal) with a
150 µm x 150 µm (5.9 mils x 5.9 mils) pitch.
Additionally most assembly vendors should be able to bond pads with 60
µm x 60 µm pad openings and 90 µm pitch. MOSIS
assembly vendors can easily bond pads with these dimensions, subject
to bonding diagram approval.
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Pads should be centered at the designated pad location.
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If vendor design rules require a single via is used under the bonding
metal, then it should be a box corresponding to the glass cut, also
centered.
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For Agilent sub-micron technologies, a ring of minimum sized vias
should be used to connect to underlying metal. The vias should not be
under the glass cuts; they should be close to the edge. In either
case, an array of minimum vias across the entire pad will cause
bonding yield problems and should not be used for this technology.
Please note that pad placement directly affects your yield. Packaged
parts that violate the following suggestions are likely to have shorts
or other bonding failures:
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The number of pads on a side must not exceed the number of bonding
fingers along the cavity edge of a package by more than two. Bonding
wires should not be at an angle greater than 45 degrees to the chip's
axis. The best rule of thumb is to distribute the pads evenly on all
four sides.
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Bonding pads should be placed along the edges of the project using the
appropriate (pitch) center-to-center spacing. Refer to the
appropriate table above for the recommended minimum.
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Bonding wires must not cross over any active circuitry or other
pads.
One way to increase the number of bonding pads on a given design size
is to have double rows. This type of bonding may be more expensive, so
designers should consult with MOSIS about pricing. Follow these
guidelines for packaging parts with two levels of bonding pads:
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The bond fingers of the package to be used line up with the pads of
the chip.
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A bonding diagram is provided by the designer that is a true
representation of the die in the package because it is drawn to scale.
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The lines on the diagram representing the bonding wires, drawn from
bonding pads on the die to the center of the package bonding fingers,
are the same width as the bonding pads (approximately 100 micrometers or 4
mils). The lines (wires) drawn should not touch one another.
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Shifting the die 250 micrometers in any direction should not cause any
lines to touch.
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No reverse bonding is allowed. Wires should not exceed 4000
micrometers (~150 mils) in length, and bonding wires from the inner
layer of bond pads should not be bonded to the package cavity.
Pad Count (MOSIS Software Estimate)
MOSIS software currently uses the following criteria to count bonding
pads.
MINIMUM_PAD_SIZE (passivation opening) = 35 µm x 35 µm
MAXIMUM_PAD_SIZE (passivation opening) = 400 µm x 400 µm
This pad count information is provided for your information only and
does not affect fabrication of any pads. All pads (bond, probe or
other) will be fabricated from your layout as submitted.
Fabrication Vendor
Rules and geometry vary among vendors and processes. Refer to the
specific vendor documents.
MOSIS SCMOS
MOSIS scalable (SCMOS) design rules for pads
Pad geometry in MOSIS scalable (SCMOS) design rules
(some processes)
4. Plastic Packages
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If you are interested in plastic packages, send a message to
support@mosis.com, specifying
the package parameters (package type, lead count, body size, and pad
size of interest).
5. Design Orientation
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By default, MOSIS will orient your die in the package cavity with the
orientation of your layout as submitted for fabrication.
To specify rotation of your die in the package cavity, update the
Special-Handling parameter with the following information.
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ROTATE-DIE-CLOCKWISE-IN-PACKAGE-CAVITY: (90, 180 or 270) DEGREES
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You must also specify rotation of your die in the package on your
customer supplied bonding diagram. Draw an "arrow" figure on your
bonding diagram pointing the top of your die as submitted for
fabrication in relation to the top of the package cavity. See
Section 12 Bonding Diagrams for example.
If the package specified has a rectangular cavity, and the design only
fits the package cavity when rotated, MOSIS will rotate your die
counterclockwise 90 degrees. To determine if your design has been
rotated, look at the bonding diagram supplied with your parts. If the
number in the center of the chip is lying on its side, your project
has been rotated.
6. Unpackaged Parts
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Users may request packaged parts, unpackaged parts (loose dies) or any
mix of both.
To request all parts unpackaged, use
Quantity-Unpackaged: ALL in your
project submission.
To request that some parts be packaged and some not, specify the
quantity for either
Quantity-Unpackaged or
Quantity-Packaged. MOSIS
will calculate the quantity of the other from your explicit or
implicit
Quantity-Ordered.
To constrained the size of your die to fit in a package assembled by
someone other than MOSIS, enter a "0" (zero) for
Quantity-Packaged and
provide the name of a
Package Available Through MOSIS.
Bare dies are
shipped in
bare die
trays that provide industry standard ESD protection. See also
die size issues.
7. Flip Chip
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Flip chip bumping is available through MOSIS. Since bumping
requirements vary, please contact the MOSIS packaging manager at
support@mosis.com for details.
8. Lids (Taping or Sealing)
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By default, all lids are taped on the packages to allow easy
removal. If semi-epoxy, full-epoxy or hermetic-ally sealed lids are
needed, a
Special
Handling request must be submitted to MOSIS during project submission.
Some packages do not allow sufficient clearance to attach lids with
tape; those lids are attached with semi-epoxy.
9. Customer Supplied Packages
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Users may supply packages to MOSIS, as long as the following items are
received two business-days in advance of the run-closing date:
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Package drawings
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Bonding diagram drawn to scale
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Packages with the appropriate pin count and cavity size (Please
provide 3 additional packages for bonding setup)
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Lids and lid assembly instructions
These items must be labeled with Design Number, Design Name, and
contact e-mail, phone, and fax information.
To specify a customer supplied package update the
Special-Handling parameter with the following:
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PACKAGE-MANUFACTURER: KYOCERA
PACKAGE-PART-NUMBER: KD-12345
PACKAGE-TYPE: DIP
PACKAGE-LEAD-COUNT: 16
PACKAGE-CAVITY-X-DIMENSION: 200 mils
PACKAGE-CAVITY-Y-DIMENSION: 200 mils
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Possible sources for Ceramic Packages for IC Assembly are listed under
Third Party Services.
10. Downbonds
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A downbond (sometimes called a substrate connection), is a wire from a
package bonding finger to the package cavity. The downbond is intended
to make an electrical connection from the package cavity to the bottom
of the chip. This bonding finger may also be connected (wired) to one
of the chip's pads; if it is, then that pad must be used appropriately
(as a GND pad for N_well CMOS, for example). The default pin is #1 for
all packages when a downbond is requested.
MOSIS does not put in downbonds unless they are requested. A minimum
of 635 micrometers (25 mils) die edge to cavity edge clearance is
required.
To request a downbond;
DOWNBOND-TO-SUBSTRATE-PACKAGE-PIN-NUMBER(S): 1, 91
11. Packaging Quality Control
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MOSIS determines the bonding diagrams for packaging based upon chip
size and pad count, taking into account any special requests.
MOSIS requires that its packaging vendors meet industry visual
inspection criteria, including checks for metalization defects,
scribing and chip defects, bond and wire inspection, and checks for
foreign material.
Each part to be packaged, and all loose die ordered by MOSIS customers
must be inspected and must meet the following specifications from MIL
STD 883, Method 2010.10, Section 5.1.
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Metalization Defects
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Sections 3.1.1.1, 3.1.1.2 and 3.1.1.6
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Scribing and Die Defects
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Section 3.1.3
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Bond Inspection
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Sections 3.2.1.2, 3.2.1.4
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Wire Inspection
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Section 3.2.2
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Foreign Material
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Section 3.2.5
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Die Mounting
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Section 3.2.3.1
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All bonded parts must have a wire bond pull strength of at least 3
grams as specified in MIL STD 883D, Method 2011.7.
12. Bonding Diagrams
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MOSIS Supplied
MOSIS can automatically generate bonding diagrams for MOSIS Standard
Ceramic Packages and MOSIS Standard
Open
Cavity Plastic Packages.
To request MOSIS-generated bonding diagrams set the BONDING DIAGRAM
SUPPLIER parameter to MOSIS when submitting your design.
If MOSIS is unable to automatically generate the bonding diagram, the
customer must provide one. See Customer-Supplied Bonding Diagrams.
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Note: Customer-supplied bonding diagrams are required for all I2A
Technologies (formerly IPAC) plastic packaging.
Preliminary (before run-closing date) and final (after run-closing
date) MOSIS-generated blank bonding diagrams are available for
download at:
https://www.mosis.com/Webforms/project_document_access.html
NOTE: Design layout is required and design must be in
the fabrication queue before MOSIS-generated blank bonding are made
available.
Customer Supplied
Customers that prefer to specify pad-to-pin assignments can do so by
providing MOSIS with a customer-supplied bonding diagram.
To request the customer-supplied bonding diagram option, set the
BONDING DIAGRAM SUPPLIER parameter to CUSTOMER when submitting your
design.
Preliminary customer-supplied bonding diagrams are provided for
customer internal use and review only and are not to be sent to MOSIS.
Final customer-supplied bonding diagrams are due within one week of
notification that final blank bonding has been posted. Notification
that the final blank bonding diagrams are available for creating final
customer-supplied bonding diagrams will be sent after the fabrication
run closing is complete.
Preliminary (before run-closing date) and final (after run-closing
date) blank bonding diagram templates to use for customer-supplied
bonding diagrams are available for download at:
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https://www.mosis.com/Webforms/project_document_access.html
General
A bonding diagram can be associated with a project only after the
design is in the fabrication queue. The procedure to check and log a
bonding diagram is done by hand, so there can be a delay in logging a
diagram of up to two days after it is received at MOSIS.
E-mail messages sent to
support@mosis.com with bonding
diagrams attached receive an acknowledgment that the e-mail message
was received.
You can
confirm the successful transmission of a bonding diagram sent by fax
by calling 310-448-9316 immediately after you send the bonding
diagram.
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Append the file in an e-mail message to
support@mosis.com. Type the
phrase "design-id Bonding Diagram Attached" in the subject line, and
attach the file using the naming convention of
"design-id_bonding_diagram," where "design-id" is the design number of
your project.
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Fax to the attention of the MOSIS packaging manager at
+1-310-823-5624. To confirm successful transmission of the fax,
please call +1-310-448-9316 immediately after you send the bonding
diagram.
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MOSIS accepts diagrams in only .pdf or .dwg formats.
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Bonding diagrams for plastic and ceramic packages with greater than
200 leads and/or multiple bond tiers must be supplied in .dwg or .dxf
format. Additionally, each bond tier must be drawn on a separate
bonding diagram for clearer reference during wire bond set-up/buy-off.
Valid bonding diagrams must:
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Be drawn to scale.
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Confirm orientation of die in the package cavity. This can be done by
drawing an arrow on the chip pointing to the top of the layout as it
was submitted for fabrication. MOSIS default orientation of the die in
the package cavity is the same as the layout was submitted.
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Include design specific reference information.
DESIGN_NUMBER:
CUSTOMER-NAME:
CUSTOMER-ACCOUNT:
PHONE-NUMBER:
FAX-NUMBER:
QUANTITY-ORDERED:
QUANTITY-PACKAGED:
QUANTITY-UNPACKAGED:
PACKAGE-NAME:
PACKAGE-CAVITY-SIZE:
MIN-PAD-SIZE-X:
MIN-PAD-SIZE-Y:
MIN-PAD-PITCH:
DIE-ROTATION(CLOCKWISE)-IN-PACKAGE-CAVITY:
(0, 90, 180 or 279)
Sample bonding diagrams in .pdf format:
Please be sure to draw your project to scale with respect to the
package cavity.
Standard packaging charges include one bonding diagram per design.
Each additional bonding diagram costs an incremental $100. This is in
addition to any other packaging charge.
13. Late Packaging Updates
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Customer packaging requirements are carefully considered when
determining optimal reticle placement/packing of customers layout.
Late packaging updates can invalidate optimal placement.
Additionally, processing late packaging updates often require the
complete rework of complicated vendor ordering instructions. As a
result of these considerations MOSIS finds it necessary to impose a
minimum $250 charge for all late packaging changes. This fee is in
addition to the standard packaging charges, and additional charges
beyond the $250 minimum may be necessary if additional wafers are
required in order to satisfy the late packaging update.
14. Bond Wire Electrical Parameters
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MOSIS packaging vendors use 1 mil gold wire by default. Other bond
wire diameters (smaller 0.8 mil or larger 1.2 or 1.3 mil) may be used
in special cases. See
Electrical Package Characterization. Under "Additional Information" select
Plastic Packages' Electrical Performance: Reduced Bond Wire Diameter (PDF).
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Length
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Wire
Length
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Bond Wire Diameter
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0.8 mil
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1.0 mil
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1.2 mil
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1.3 mil
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Resistance (Ohm)
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5 mm
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0.383
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0.257
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0.198
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0.180
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2 mm
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0.154
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0.103
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0.079
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0.072
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Inductance (nH)
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5 mm
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6.103
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5.869
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5.668
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5.576
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2 mm
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2.089
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1.996
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1.915
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1.879
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Capacitance (pF)
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5 mm
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0.202
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0.242
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0.279
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0.299
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2 mm
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0.104
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0.122
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0.140
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0.149
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Mutual Inductance (nH)
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5 mm
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3.320
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3.318
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3.314
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3.311
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2 mm
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0.9798
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0.9787
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0.9770
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0.9758
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Mutual capacitance (pF)
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5 mm
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-0.0374
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-0.0488
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-0.0602
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-0.0698
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2 mm
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-0.0204
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-0.0261
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-0.0327
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-0.0364
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15. ESD
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Designers and end users must enforce appropriate protective
measures against static discharge damage. ESD protection should
be employed in the design whenever possible, and parts should be
handled only by trained operators in a static-controlled
environment.
MOSIS handles wafers and singulated and packaged parts in a
static-controlled environment with regulated humidity and
conductive or dissipative flooring, work surfaces, carriers, and
tools. Personnel wear conductive outer garments and gloves and a
conductive wrist strap when handling any semiconductor product
material. Parts are shipped in static-dissipative, protective
packaging.
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Related Links
Fabrication Schedule
Customer Support
MOSIS Products
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