SEFAR INC.
Product
Information
Guide for Precision
Electronic Screens
CONTENTS...
Products & Services
2
Mesh Specifications
3-4
Cast Frames
5
Emulsion Thickness Data
Image Alignment Fixture
6
Emulsion Data
7-8
CAD & Photo-Plotting
9
Consumables
10
Photovoltaic Screens
11
Technical Center Services
12
Ordering Screens
13
Mesh Selection Guide
13
COMBINED LEADERS...
TOTAL VALUE-ADDED SERVICE
Sefar Inc. is part of a world wide organization which includes the world’s
leading manufacturer of polyester woven fabric and one of the world’s largest
organizations for the fabrication and distribution of screens across a broad
industry spectrum. In the United States, Sefar Inc. is the largest manufacturer
of commercial thick film screens for the electronics industry. With more than
175 years of experience in weaving and screen fabrication, Sefar Inc. offers
their customers the benefit of their knowledge in the development of product
quality and the advancement in technology.
In 2001, Sefar Inc. acquired the Microcircuit Engineering Corporation (MEC).
A pioneer of screen-printing mesh technology, MEC brought over 35 years
of industry experience to Sefar Inc., launching the company into the thick
film screen market with a strong emphasis on quality and technical support.
In 2003, Sefar Inc. acquired Seri-Max, a premier supplier of stretched screens
and supplies to the CD/DVD decorating market. The addition of Seri-Max
provided two additional screen fabrication networks in the US, which helped
Sefar Inc. expand their screen-making capabilities further into the textile,
container and optical disc market segments.
In 2005, Sefar Inc. acquired Hybrid Screen Technologies, Inc. (HST). An
independent organization since 1993, HST also evolved from the origins of
the thick film industry in the US. With a west coast and midwest screen
facility, HST, helped Sefar Inc. to successfully provide a nationally available
network of support specialized for today’s thick film customer.
In 2006, Sefar Inc. acquired Rigsby Screen and Stencil, Inc. The talent,
experiences and resources of this eighteen year veteran of the thick film
industry brought additional expertise to Sefar Inc.’s California location. The
combined knowledge and history of Rigsby Screen and Stencil, Inc. and Sefar
Inc. adds extra depth to the support available to customers interested in time
tested solutions and repeatable results.
Combining these leaders in the screen-printing industry, Sefar Inc. is
committed to the assurance of quality, service and technical support in all of
its products. These products include; pre-stretched screens, presensitized or
coated screens, and imaged screens. Sefar Inc. also provides an in-house laser
plotting service and a CAD staff to plot, convert or draw customer artwork.
A complete list of screen-printing accessories is also available to support the
needs of our customers.
ISO 9001 Certified
1
PRODUCTS & SERVICES
Fabricated Screen Applications
Related Products & Services
Š Thick Film Micro-Electronics
Š Hybrid Circuits
Š Solar and Photovoltaic applications
Š MCM’s
Š Ultra-Fine Lines
Š Microelectronic Packaging
Š Low Temperature Co-Fired Ceramics
Š Diffusion Patterning Process
Š Solder Paste & Adhesives
Š Membrane Switch Circuits
Š Electronic Display Systems
Š Printed Circuits
Š Precision Graphics & Compact Discs
Š Screen Tension Meters
Digital and mechanical tension meters
Š Large Chases & Tubular Frames
Custom sizes available
Š CAD Artwork Generation & Laser Photoplotting
Precision plots in 1/4, 1/8, 1/25 and 1/40 mil resolutions.
CAD artwork generation and modification including
image reduction, step and repeat, editing and Gerber®
file conversion.
Š Precision Machined Squeegee Blades
Various squeegee blades in Durometers to fit
almost any Thick Film or SMT printing application.
Screen Fabrication Options
Š Frames for Purchase
Precision cast aluminum screen frames from
5” x 5” up to 24” x 24” are available from Sefar
Printing Solutions, Inc.
Š Mesh Only Screens
The foundation of Sefar’s high quality screens
begins with Sefar mesh products. Premium
stainless steel and Sefar polyester mesh are
properly stretched and balanced to optimal
tension across our (or your) frames at any of the
following angles: 45°, 30°, 22.5°, and 90° (± 3°)
Š Presensitized Screens
Our high performance, dual cure emulsions are
uniformly coated onto our stretched screens from
0.0001” thick or greater. Sefar’s cleanroom
coating environment eliminates image defects,
providing screens ready for quick exposure in
your facility.
Š Imaged Screens
Screens arrive at your facility ready to print.
Highly skilled quality-conscious Sefar technicians
image and develop your screens from film
positives you supply or we generate from your
supplied drawing or electronic file.
2
Š Cleaning Wipes
General purpose to ultra-clean room grade wipes
Š Exposure/Drying/Developing Equipment
Screen exposure units
Pattern alignment fixtures
Screen developing & drying equipment
Value Added Services
Š ISO 9001 Certified
All Sefar Inc. screen stretching locations are ISO 9001
Certified to help you meet your stringent quality standards.
Š Quality Control
Sefar conducts a 100% inspection at each step in
the manufacturing process to ensure screens
exceed quality expectations.
Š Experienced Product Support
Sefar offers an extremely qualified portfolio of
experts to provide service and support before,
during and after the purchase of Sefar products.
WIRE MESH
Sefar uses the finest stainless steel wire cloth in our screen
manufacturing process; high strength, better tension-retaining
properties and exceptionally uniform mesh thickness. Calendered (Cal) stainless steel mesh is also available. A calendered
mesh is slightly flattened between two heavy rollers to create a
thinner, smoother and more uniform mesh (the mesh opening size and open area are unaffected). As a result, calendered
wire typically is 20% thinner than standard wire mesh, resulting in a thinner ink deposit during printing (see photo right).
Sefar Precision Stainless Steel Wire Cloth Specifications
Mesh Count
Wire Diameter
Mesh
Opening
Open Area
Weave
Thickness
Recommended Wet Print
Tension
Thickness
(wires/inch)
(inches)
(inches)
(%)
(inches)
(N/cm)
30
0.0065
0.0268
(inches)
64.8
.0115-.0140
42-52
0.0081
50
0.0055
0.0145
52.6
.0094-.0106
42-52
0.0053
60
0.0045
0.0130
58.3
.0081-.0095
42-52
0.0051
80
0.0020
0.0105
70.5
.0041-.0046
18-24
0.0030
80
0.0037
0.0088
49.5
.0080-.0089
26-42
0.0042
105
0.0030
0.0070
46.9
.0060-.0067
26-42
0.0030
120
0.0026
0.0065
47.3
.0052-.0058
26-42
0.0026
135
0.0023
0.0057
47.3
.0052-.0058
26-42
0.0026
145
0.0022
0.0047
46.4
.0045-.0050
26-42
0.0022
150
0.0026
0.0041
37.2
.0052-.0058
26-37
0.0020
165
0.0020
0.0041
44.9
.0041-.0046
26-37
0.0019
180
0.0018
0.0038
45.7
.0038-.0043
26-37
0.0018
200
0.0021
0.0029
33.6
.0041-.0046
26-37
0.0014
200
0.0016
0.0034
46.2
.0033-.0038
29-35
0.0016
200
0.0014
0.0035
51.8
.0029-.0034
26-34
0.0017
230
0.0014
0.0029
45.9
.0029-.0034
22-34
0.0014
230
0.0011
0.0032
54.0
.0023-.0026
18-24
0.0014
230 Cal
0.0011
0.0032
54.0
.0017-.0019
18-24
0.0010
250
0.0016
0.0024
36.0
.0033-.0037
26-37
0.0013
270
0.0014
0.0023
38.6
.0029-.0034
26-36
0.0012
280
0.0010
0.0026
53.0
.0018-.0022
17-23
0.0011
280
0.0012
0.0024
44.1
.0025-.0029
21-33
0.0012
290*
0.0008
0.0027
60.0
.0016-.0019
15-28
0.0011
325
0.0009
0.0022
50.1
.0019-.0022
15-21
0.0011
325 Cal
0.0009
0.0022
50.1
.0012-.0015
15-21
0.0007
325
0.0011
0.0020
41.3
.0022-.0026
21-32
0.0010
325 Cal
0.0011
0.0020
41.3
.0017-.0019
21-32
0.0007
360*
0.0006
0.0022
60.0
.0012-.0016
15-28
0.0008
400
0.0009
0.0016
40.0
.0017-.0020
18-25
0.0008
400
0.0010
0.0015
37.0
.0018-.0022
20-30
0.0007
400 Cal
0.0010
0.0015
38.0
.0015-.0018
20-30
0.0006
400
0.0007
0.0018
51.0
.0014-.0017
15-21
0.0008
400 Cal
0.0007
0.0018
51.0
.0009-.0011
15-21
0.0005
0.0013
42.3
.0010-.0013
15-21
0.0005
500 Cal*
0.0007
*High tensile strength alloy mesh
Cal = calendered mesh
Wire mesh specification accuracy is within 4% of Mesh Count
3
POLYESTER MESH
SEFAR® PET 1500
SEFAR® PET 1500 is the industry’s leading low elongation polyester mesh which features improved stencil
adhesion properties. It is available in the widest range of thread diameters and mesh counts. SEFAR®
PET 1500’s increased mesh strength and durability combined with low elongation provide:
Š Higher tension levels
Š Low elongation
Š Superior print quality
Š Increased durability
Š Consistent registration throughout the entire run
Š Machine utilization optimization
SEFAR® PET 1500 - Low Elongation Polyester Mesh
Mesh
Specification
60-140
Mesh Count
Mesh Opening
Thread Diameter
Open Area
Mesh Thickness
(t.p.i.)
(µm)
(µm)
(%)
(µm)
60
270
140
250
76-140
76
188
140
31.9
260
83-100
83
209
100
44.5
165
92-100
92
174
100
39.1
160
110-80
110
149
80
40.8
130
123-80
123
122
80
34.5
130
137-64
137
115
64
38.7
103
156-64
156
90
64
30.1
101
175-55
175
85
55
33.5
85
195-55
195
67
55
26.5
88
230-48
230
55
48
24.6
81
240-48
240
50
48
22.8
81
255-48 TW
255
45
48
20.3
88
280-34
280
54
34
35.2
55
280-40
280
47
40
26.6
65
305-34
305
45
34
29.6
55
330-34
330
40
34
26.9
53
355-34
355
31
34
19.4
55
355-34 TW
355
33
34
21.3
62
380-31
380
32
31
23.3
47
460-27
460
22
27
15.1
43
All above product descriptions are plain weave unless designated TW (twill weave).
4
41.9
CAST FRAMES
Sefar’s cast aluminum screen frames are designed for dimensional
stability and tension-retaining properties. Each new Sefar cast frame
is precision ground and inspected for flatness, parallelism, thickness, mounting hole location and thread size. We offer all industry
standard cast frame sizes from 5” x 5” up to 24” x 24” to fit most
thick film screen printers today. Should larger frames be required,
custom tubular extrusion frames or self-tensioning chases are available. (Please consult Sefar for recommendations and availability.)
Sefar Cast Aluminum Screen Frame Parameters
I. D.
O. D.
Corner Hole
Locations
Hole Size
Frame
Thickness
Flat &
Parallel ±
Standard
Stencil Size
(inches)
(inches)
(centers, in inches)
(thread size)
(inches)
(inches)
(inches)
5x5
6.70 x 6.70
5.875 x 5.875
10/32
0.735 ± 0.002
0.003
4x4
8 x 10
9.65 x 11.70
8.500 x 10.750
1/4 - 20
0.735 ± 0.002
0.003
6x6
10 x 10
11.70 x 11.70
10.000 x 10.000
1/4 - 20
0.735 ± 0.002
0.005
6x6
12 x 12
14.10 x 14.10
13.000 x 13.000
1/4 - 20
1.000 ± 0.002
0.003
8x8
12 x 17
15.00 x 20.00
13.000 x 18.000
1/4 - 20
1.000 ± 0.002
0.005
7 x 12
15 x 15
17.70 x 17.70
16.000 x 16.000
1/4 - 20
1.000 ± 0.002
0.003
10 x 10
20 x 20
23.10 x 23.10
21.000 x 21.000
1/4 - 20
1.000 ± 0.002
0.005
15 x 15
24 x 24
28.10 x 28.10
26.000 x 26.000
1/4 - 20
1.000 ± 0.002
0.005
20 x 20
Trampoline Mounted Screens from Sefar Inc.
Learn how trampoline mounted screens from Sefar can be a cost-effective and
astute alternative for fine line, high resolution, high mesh count applications.
Consisting of stainless steel wire mesh supported by a border of polyester mesh, a trampoline screen combines the best properties of both mesh types.
The high mesh count stainless steel mesh is ideally suited for fine line, high resolution printed line applications (these printing characteristics are difficult to achieve with other types of mesh). Polyester mesh has
superior elasticity properties that are well
suited for high volume printing, tension
consistency and the flexibility required for
the constant deformation associated with
off contact printing.
In combination, these two mesh types
create a screen that has excellent print
performance, long screen life and higher
process yields. For this reason, trampoline
screens are an excellent choice if you are
looking to reduce the financial burden associated with expensive, fine line printing
applications.
5
EMULSION THICKNESS DATA
Sefar dual cure & PVA/PVOH/Diazo direct screen
emulsions can be applied to our stretched screens in
thicknesses from 0.0001” to 0.030” (increments of
0.0001”) to the following tolerances:
Emulsion Thickness
Base coat to 0.0007”
0.0008” to 0.0030”
0.0031” to 0.0060”
0.0061” to 0.0150”
0.0160” and Greater
Tolerances
± 0.0001”
± 0.0002”
± 0.0005”
± 0.0010”
± 0.0015”
Determining Screen Emulsion Thickness
The emulsion thickness your screens require can be
determined in a number of ways:
Š Ask your ink supplier for a recommendation based
on your application.
Š Contact Sefar’s technical service staff for a
recommendation based on current industry standards.
Š Calculate the emulsion thickness you need based on
the following formula:
Te = Tw – (Tm x Ao)
When: Te = emulsion thickness
Tw = wet printed thickness
Tm = weave thickness
Ao = % of open area
You will need to know the wet printed thickness you
are trying to achieve as well as the parameters of the
screen mesh you will be using in order to complete
the above equation. This equation can be modified
for use in determining the theoretical wet printed
thickness achievable from any screen mesh/emulsion
thickness combination. The equation for determining
theoretical wet printed thickness is shown below (the
same conditions apply):
Tw = (Tm x Ao) + Te
(Factors affecting print thickness which relate to ink, screen printing equipment, setup parameters, etc., are not considered)
IMAGE ALIGNMENT FIXTURE
Sefar’s Image Alignment Fixture is designed to
accurately position film positives to the center of the
mounting holes of standard size presensitized screen
frames. Aligning to the center of the mounting holes
of the frame will cause the Image to be centered under
the print head when the screen is mounted onto the
screen printer. The clear Lucite® fixture consists of a
flat base, removable corner pins, appropriately located
threaded inserts and centralized screen support block
displaying center and diagonal lines. The screen is
placed, squeegee-side down onto the screen support
block, with the corner pins passing up through the
corner holes in the frame. The operator then aligns the
film positive so that the positive’s center lines directly
overlay the center lines on the fixture’s screen support
block. Image location accuracy is operator dependent,
but is typically ± 0.035”.
The following size Image Alignment Fixtures are
available:
Š For 5” x 5”, 5” x 7”, 6” x 8” and 7” x 8” frames (ID)
Base: 16” x 16” x 0.375”
Block: 4” x 4” x 1.0”
Š For 8” x 8”, 8” x 10” and 10” x 10” frames (ID)
Base: 16” x 16” x 0.375”
Block: 7.5” x 7.5” x 1.0”
Š For 12” x 12” and 15” x 15” frames (ID)
Base: 20” x 20” x 0.375”
Block: 10” x 10” x 1.250”
6
Š For 20” x 20” frames (ID)
Base: 30” x 30” x 0.375”
Block: 10” x 10” x 1.250”
EMULSION DATA
Sefar Screen Emulsions
Premier Dual Cure Thick Film Screen Emulsions
High Quality PVA/Diazo Emulsions
e-11: Ultra-fine line resolution capabilities (30 µm
line and spaces) with razor sharp edge definition. e-11
has excellent gasketing characteristics as well as superior
solvent resistance. High sensitivity to ultraviolet (UV)
light means quick exposures. Use e-11 for the most demanding microelectronic printing applications, especially
when resolution and edge definition are critical.
ES: ES offers sharp edge definition with exceptional solvent and very good abrasion resistance. Easy processing.
MM-B: Ultra-fine resolution capabilities with crisp
edge definition. The MM-B emulsion has almost unlimited resolution potential and a superior resistance
to chemical solvents and abrasive pastes. The high
percentage of solvents and high cross-linking energy
requirements require a longer exposure time during
image processing. Exhibits its best performance when
imaged by Sefar’s trained technicians.
Pure Photopolymers
e-80: e-80 has outstanding resistance to cleaning
solvents and ink vehicles. Combine this with its excellent gasketing and printing characteristics and e-80
becomes a great choice for applications which involve
printing or cleaning with aggressive materials.
e-95: The clear base of e-95 is specially formulated
to provide easy print and deep UV penetration during
exposure. Very user-friendly with respect to processing,
exposes in a fraction of the time of conventional PVAPVOH type emulsions, with quick and easy development
washout. Excellent for heavy deposits of solder paste or
adhesives, e-95 can be specified up to 30 mils thick.
EG: EG displays good gasketing and solvent resistance
along with easy processing characteristics.
PEF2: A direct/indirect emulsion application or film
based emulsion system, PEF2 combines precision emulsion thickness control with excellent substrate gasketing
properties and high resolution imaging capabilities. An
ideal choice for presensitized screens, this emulsion has
a rapid exposure time and is easy for the customer to
washout. Best suited for applications with greater than
0.0003” EOM.
PE: A direct emulsion product with all of the same
characteristics of PEF2, but ideally suited for very thin
emulsion build-ups of equal to or less than 0.0003”
EOM. Pure photopolymers are softer and more conforming to gasket multi-layer thick film applications in
a non-aggressive environment.
DCE9: With a longer exposure time, DCE9 demonstrates more of the properties of the classic Diazo
emulsion formulations. A direct emulsion specifically
formulated for harsher solvents such as NMP, DCE9
provides an excellent option as an emulsion choice in
aggressive chemical environments. Resolution features
are the most favorable in thinner emulsion build-ups,
but this emulsion gaskets well and is easily handled by
a customer exposing the screen in-house.
MH: A dual cure emulsion with very high water resistance to be used for long-run water-based print applications. Very high mechanical and abrasion resistance
which qualifies it as ideal for abrasive inks and substrates.
The Micro-Vu inspection system is used to verify the
dimensional stability of the image in the emulsion.
7
EMULSION DATA
Sefar Emulsion Cross-Reference Chart
Emulsion
e-11
MM-B
Toluene
1
1
Xylene
1
NMP
e-80
e-95
DCE9
MH
ES
EG
PEF2
PE
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
4
3
3
4
2
4
4
4
4
4
Distilled Water
3
1
2
3
1
2
4
4
3
3
Butyl Carbitol
1
1
1
1
1
1
2
1
1
1
Butyl Cellosolve
1
1
1
1
1
1
1
1
1
1
Butyl Carbitol Acetate
1
1
1
1
1
1
2
2
1
1
Isopropanol
1
1
1
1
1
1
1
1
2
2
1,1,1 Trichloroethane
2
1
1
1
1
2
2
2
2
2
Terpineol
1
1
1
1
1
2
1
1
2
2
Methyl Ethyl Keytone
3
2
1
3
2
2
1
2
2
2
Acetone
2
1
1
2
1
1
1
2
1
1
Methanol
1
1
2
3
1
4
4
3
3
3
Rosstech 106 FE
1
1
1
1
1
1
1
1
1
1
Rosstech 133
1
1
1
1
1
1
1
1
1
1
Axarel 2000
1
1
1
1
1
1
1
1
1
1
* Softness measured on the SWARD-ZEIDLER® relative hardness scale
Legend: 1 = Safe; 2 = Reasonably safe, 3= Use with caution, 4 = Not Compatible
400.0007” calendered mesh, 0.0006” emulsion,
imaged with 50 micron lines at 100x
8
400.0007” calendered mesh, 0.0006” emulsion,
imaged with 40 micron lines & 100 micron vias at 220x
CAD & PHOTO-PLOTTING
Laser Photoplotter
Our Laser Photoplotting System can accurately
reproduce the high resolution and the sharp edge
definition needed for today’s precision electronic
designs. Using this system, our staff of certified
Gerber® trained photo technicians can generate
sharp, accurate photo-plots for a wide variety of
imaging applications.
Performance Specifications:
Output Media: Silver-Halide Coated Film
Maximum Film Size: 22” X 28”
Maximum Film Thickness: 0.007”
Maximum Film Image Size: 21.5” X 27.5”
Accuracy: ± 0.5 mil
Repeatability: ± 0.5 mil
Resolution: 1/4, 1/8, 1/25 and 1/40 resolution
Š 24-Hour Turnaround (File must be received by 3 PM EST)
Š Competitive Pricing
Š Formats: Gerber® Files
AutoCAD .dwg and .dxf files
Adobe® Illustrator
Sefar features a complete range of CAD drafting
artwork generation and file editing using the latest
version of AutoCAD software. Data for CAD service
and/or photo plotting may be supplied either on disk,
electronic file, or as a dimensioned drawing. Any
electronic data supplied which is not in Gerber®
format can be translated into a Gerber® file for a
nominal charge.
9
CONSUMABLES
Squeegees
Cleaning Wipes
Sefar offers an extensive range of solvent resistant,
polyurethane squeeges that are available in a variety
of different durometers, colors, sizes, profiles and
composites. When ordering squeegees, it will be
necessary to provide us with the following information:
From general purpose to clean-room applications, Sefar
Inc. offers a complete line of cleaning wipes for screens,
squeegees, printers, stampers, and workstations. Available dry or pre-saturated.
Size
Squeegee is available in standard coil lenghths of 144”
(to be cut by the customer). Additional sizes are available—contact your Sefar Representative to inquire
about our current inventory.
Durometer
Durometer refers to the hardness of the squeegee
blade, each durometer designed to provide the printer
with a different print effect. If you are not sure which
durometer to use, feel free to contact Sefar Technical
Services for assistance. Squeegees are typically color
coded according to the durometer.
Squeegee Profile
The profile refers to the shape of the squeegee’s
printing edge. Common squeegee profiles for
electronics are straight and diamond (see below).
Squeegee Profiles
Bemcot M-3
5” x 5” spunbond filament fabric made from cotton
cellulose. Very soft, high absorbancy, lint-free.
Bemcot S-2
5” x 5” economical, thinner cotton, lint-free wipes.
Blue Guard
A highly absorbent wipe, featuring a hydro-entagled
blend of cellulose and polyester fibers for dimensional stability. Non-woven, excellent wicking action, tear-resistant.
Blue Guard wipes are 12” x 13” in size.
810 Ultrasonic Laundered
9” x 9” wipes made with 100% continuous filament polyester fiber. Excellent cleaning performance with extremely
low particle generation. Very soft (becomes softer when
wet) and will not scratch or damage the stencil.
Vision 1 Unlaundered
One of the most popular wipes used for screen printing
applications where lint-free cleaning is critical. 9” x 9” in
size, made with polyester.
Sponge Tech 2000
Fully reticulated (open cell) polyurethane foam wipe—the
only true lint-free, non-abrasive cleaning tool. Excellent
absorbancy, reusable, 6” x 9” in size.
Straight Diamond
401 Understencil
9” x 9” wipe specifically made for cleaning solder paste,
flux residue, inks and epoxies from SMT stencils. Tear and
shred-resistant.
PRE-SATURATED
Economy Wipes
5” x 8” polyester wipes, presaturated with IPA and
deionized water.
Screen Clean
5” x 8” polyester wipes, presaturated with Rosstech 119
safety solvent to clean inks, epoxies and thick film pastes.
10
PHOTOVOLTAIC SCREENS
Today’s Technology for Tomorrow
Capacity for your Demands
With the growing awareness for alternative power resources today, Sefar Inc. recognizes the importance for
the solar cell and photovoltaic industries to work with
dependable partners to insure both manufacturing
efficiency and the highest quality standards. With over
40 years of combined experience and technical expertise for supplying solar and thick film screens to the
industry, Sefar Inc. is dedicated to the advancement
of this technology, and providing the solar cell market
with precision screens for their innovative designs.
Growth in the solar power industry has made the customer demand for this technology to increase significantly in the last decade. With three North American
locations to serve you, Sefar Inc. is capable of providing large volumes of solar screens on-demand—having the largest capacity for stretched screens in the
US. Our stretching facilities are located in the West
(California), Midwest (Minnesota) and East (New
Jersey), making it easy for us to serve you regionally—
and nationally if your need for screens increases with
industry growth and expansion.
Screen Making Services
Artwork: Sefar Inc. CAD department is capable of
designing and supplying precision solar films for our
customers that contain fine line widths in the 3 mil
range (tolerance of +/- 3 microns). Our experience in
providing solar films to the industry for over a decade and our dedication for working closely with the
customer ensures that we can help you best achieve
your desired, target line thickness for your specific
application.
Screens: Equipped with state-of-the-art stretching
equipment and 70+ years of combined stretching
experience, Sefar Inc. is capable of stretching any frame
size, shape or type, to a desired tension using your
stainless steel mesh of choice. As the largest supplier of
stretched screens in North
America, Sefar Inc. can
accommodate any screen parameter
that your application requires.
Coating and Imaging: Capable of providing
screen coating and imaging services that excel
above solar industry standards, Sefar Inc. is well
equipped to be your full-service partner for solar
screens. We offer a wide variety of emulsions that
are capable of producing 3 mil and finer finger
widths that are necessary for specialized solar applications. With the help of our technical experts,
the correct emulsion can be selected for your solar
application based on variables such as solvent resistance, fine line requirements and durability against
abrasive materials.
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TECHNICAL CENTER SERVICES
Sefar Inc. operates a Technical Center in concert with
their Minnesota fabrication facility. The Technical Center
offers training and customer assistance to individuals
and groups interested in experiencing hands-on printer
setup and operation, technical seminars and mesh
product analysis.
The training class for screen printer setup and training
includes a plant tour of the screen fabrication facility, a
discussion of the correct mesh and emulsion selection
and a hands-on demonstration of screen printing
techniques. Attendees will setup and print fine-line
electronic patterns with artwork and materials supplied
by Sefar and its printing industry partners. The class
can also be customized to address a specific customer
related process problem. While not a prototype lab, the
Technical Center provides a process dryer and various
analytical tools to measure the attendee’s progress.
Each attendee will leave with a substrate printed during
the class as evidence of their new proficiency.
The resources of the screen printer training class include
an AMI Model MSP-885 screen printer, alumina and
green tape substrates, gold and silver conductive pastes,
and, of course, a wide selection of mesh and emulsion
combinations for screen assembly. Additional resources
available to customer specific requirements include via
fill metal masks and epoxy deposition stencils.
The screen printer training class can also go on the road
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for customer site visits and instruction. Using customer
supplied resources, Sefar Inc. can provide the same
screen printer setup training available at the Technical
Center, but in the familiar setting of the customer’s own
manufacturing facility.
Technical seminars organized by the Sefar Technical
Center address many new topics relative to the industry
where the screen plays an important role. With an
industry presence in many diverse electronic fields, Sefar
Inc. has acquired detailed knowledge and experience
in problem solving, process innovation and emerging
technologies.
In addition to the training and seminar opportunities,
the Sefar Technical Center offers customer support
with regard to mesh product analysis. Mesh selection
based on application, recommended tension levels, and
aligning your process for optimum mesh performance
are part of the resources available to our customers
interested in a more aggressive approach to problem
solving, process design or mesh product knowledge.
The Sefar Technical Center is a focal point for
investigating, sharing and developing the latest
advances in Printing Solutions. It is our name and
it is our mission.
ORDERING SCREENS
MESH SELECTION GUIDE
Contact our Inside Sales Group at 609.613.5000 to place
an order for stretched screens. They will contact your
Regional Territory Sales Manager, or one of our technical
experts if further assistance is needed.
Selecting the proper screen parameters for your specific
printing application will help to insure successful results.
To insure that your screens are made to your specifications,
it is important for you to provide us with adequate
information when placing an order. Please be prepared to
provide the following screen parameters:
‡ Frame Size
If you need to purchase frames, please be sure to
provide information on your frame requirements. For
more information please reference the chart on page
5. If you will be providing us with your frames we will
need to know the frame size for pricing purposes.
‡ Mesh Specification
When providing us with your mesh requirements, be
sure to include both mesh count and wire diameter. For
more information please see the charts on pages 3 & 4.
‡ Mesh Tension
Unless you require a special tension, all screens are
stretched to established standards according to the cloth
characteristics, such as mesh count and wire diameter.
‡ Mesh Angle
When determining mesh angle on your screens, it is
important that none of the wires run parallel to the
lines in your pattern (this can cause a reduction in the
anticipated feature width and shape). Common angles
are 45˚ and 22˚.
‡ Emulsion Thickness
If you would like your screens to be coated with
emulsion, please provide your emulsion over mesh
(EOM) build-up. You may also specify total screen
thickness (including mesh thickness). For more
information on wet deposit, reference our Mesh
Specification Chart on pages 3 & 4, and the Emulsion
Thickness calculation on page 6.
‡ Artwork
If we are coating your screens, we can image them
too! Artwork can be supplied, or we can output
your electronic files in-house. We accept AutoCAD’s,
.dxf, and .dwg files, as well as Gerber® and Adobe®
Illustrator files. Please provide artwork details during
the submission process (positive or negative films, right
or wrong-reading images, etc.).
‡ Image Orientation
When imaging screens that are on rectangular
frames, please provide accurate instructions on image
orientation to the frame.
Screen Frames: While all frames need to be flat and
parallel, and structurally stable to maintain tension and
dimensional accuracy, they also must be the appropriate
size. The inside dimension of your frame should be at
least 2 to 3 times the length of your squeegee blade
as well as 2 to 3 times the anticipated squeegee travel
distance. This provides enough margin for proper screen
deflection while minimizing possible distortion.
Screen Mesh: Screen mesh should be selected based
on criteria directly related to your ink and application.
Initially, choose mesh count and thread diameter
combinations that are capable of printing the wet ink
thickness your application requires. Wet ink thickness
can be estimated for any mesh type using this formula:
WPT = (MT x OA) + EOM
when: MT = mesh weave thickness
OA = percentage of open area
EOM = emulsion over mesh
Additionally, the mesh type selected must also be
capable of printing the smallest feature size in your
artwork pattern. An easy method of determining
resolution capability is to compare the smallest feature
of your artwork to the width of two wire diameters
plus two mesh openings of the mesh type you’re
considering. Your smallest artwork feature should be
equal to, or larger than, this accumulated distance.
Finally, to avoid clogging, the mesh selected must also
contain openings between wires which are at least 3 to
5 times larger than the size of largest particle dispersed
in the ink you will be using.
Emulsion Coating: Screen emulsion reproduces your
artwork geometry, and acts like a gasket on the underside
of the screen mesh to help prevent ink bleed. The
thickness of this emulsion coating or EOM (“emulsionover-mesh”) has direct influence on printed thickness
when the artwork features are smaller than 0.100” (2.54
mm). EOM has less influence on wet ink thickness as
pattern features increase in size beyond 0.100”.
Since EOM affects screen thickness, it also influences
resolution capability. The smallest feature size of your
artwork must be larger than the overall thickness of the
emulsion coated screen. For most applications, 0.0005”
(13µ) EOM is usually an appropriate emulsion thickness.
Contact Sefar’s Technical staff for additional assistance
when selecting screen parameters.
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Fabrication Locations
New York
Sefar Inc.
111 Calumet Street
Depew, NY 14043
California
Sefar Inc.
1956 S. Lynx Place
Ontario, CA 91761
Missouri
Sefar Inc.
4421 NE 34th Street
Kansas City, MO 64117
Sales Office
11.09
National Headquarters
Sefar Inc.
111 Calumet Street
Depew, NY 14043
Phone: 716 683 4050
Fax:
616 683 4053
e-mail: spsales@sefar.us
www.sefar.com