ETC AS221-306

Suggested PCB Land Pattern Designs for
Leaded and Leadless Packages and Detailed
Surface Mount Guidelines for Leadless Packages
Below are sample printed circuit board land pattern
dimensions. These are based on the IPC (Institute for
Interconnecting and Packaging Electronic Circuits) surface
mount design and land pattern standard: IPC-SM-782.
These drawings are for reference only. It is recommended
that you consult with the company doing the component
mounting and soldering to the printed circuit board. These
companies have more information on options (various
possible dimensions) of actual land patterns.
0.051 (1.30 mm)
0.026
(0.65 mm)
0.087
(2.20 mm)
0.055
(1.40 mm)
0.020 (0.50 mm)
SC-70
375 µm
0.075
(1.90 mm)
600 µm
0.037
(0.95 mm)
250 µm
Chip Scale
0.087
(2.20 mm)
0.055
(1.40 mm)
0.014
(0.35 mm) NOM.
0.039
(1.00 mm)
SOT-23 3 Lead
0.014 (0.35 mm) NOM.
0.053
(1.35 mm) NOM.
0.075 (1.90 mm)
SC-79
0.095 (2.40 mm)
0.087
(2.20 mm)
0.067
(1.70 mm)
0.030
(0.80 mm)
0.031 (0.80 mm)
0.057 (1.44 mm)
0.035
(0.90 mm)
0.039 (1.00 mm) MIN.
0.039
0.047 (1.20 mm) MAX. (1.00 mm)
SOD-323
SOT-143
Skyworks Solutions, Inc. [781] 376-3000 • Fax [781] 376-3100 • Email sales@skyworksinc.com • www.skyworksinc.com
Specifications subject to change without notice. 10/02A
1
Suggested PCB Land Pattern Designs for Leaded and Leadless Packages
and Detailed Surface Mount Guidelines for Leadless Packages
0.70 mm REF.
2.4 mm
REF.
1.0 mm REF.
3.4 mm
REF.
5.200 mm
2.200
mm
0.95 mm REF.
0.95 mm REF.
0.600 mm
SOT-5, SOT-6
1.270 mm
14 Lead SOIC Narrow Body
5.8 mm
4.1 mm
2.4 mm
0.65
mm
9.2 mm
0.4
mm
1.7 mm
MSOP-8
2.2 mm
9.4 mm
1.27 mm
7.2 mm
16 Lead SOIC Wide Body
0.65
mm
5.0 mm
2.2 mm
0.40
mm
0.6 mm
9.2 mm
8 Lead SSOP (5.3 mm)
2.2 mm
1.27 mm
0.6 mm
28 Lead SOIC Wide Body
2
Skyworks Solutions, Inc. [781] 376-3000 • Fax [781] 376-3100 • Email sales@skyworksinc.com • www.skyworksinc.com
Specifications subject to change without notice. 10/02A
Suggested PCB Land Pattern Designs for Leaded and Leadless Packages
and Detailed Surface Mount Guidelines for Leadless Packages
2.200 mm
0.020 (0.50 mm)
0.026 (0.65 mm)
0.600 mm
0.010
(0.25 mm)
0.165
(4.20 mm)
0.110
0.126 (2.79 mm)
(3.20 mm)
SQ.
0.013
(0.33 mm)
Typ. GND
VIA
1.270 mm
0.008
0.063
(0.20 mm)
(1.60 mm)
TYP.
5.200 mm
Lead Length of LPCC
8 Lead SOIC Narrow Body
Outside
of Package
Lead Width
Footprint of PCB Land =
Lead Length +0.1 mm
2.200 mm
0.600 mm
1.270 mm
LPCC-16 Lead 4 x 4 mm (-307)
Surface Mount Land Pattern
0.020
(0.50 mm)
0.013
(0.33 mm)
0.020
(0.50 mm)
5.200 mm
0.122
(3.10 mm)
SQ.
0.013
(0.33 mm)
TYP.
0.020
(0.50 mm) GND VIA
SOIC-8
0.020
(0.50 mm)
0.063
(1.60 mm) TYP.
QFN-32 Lead 5 x 5 mm (-310)
Surface Mount Land Pattern
5.200
mm
2.200
mm
0.65 mm REF.
0.65 mm REF.
0.600 mm
1.270 mm
16 Lead SOIC Narrow Body
1.65 mm REF.
0.75 mm
REF.
0.40 mm REF.
SC-88 (6 Lead SC-70)
Skyworks Solutions, Inc. [781] 376-3000 • Fax [781] 376-3100 • Email sales@skyworksinc.com • www.skyworksinc.com
Specifications subject to change without notice. 10/02A
3
Suggested PCB Land Pattern Designs for Leaded and Leadless Packages
and Detailed Surface Mount Guidelines for Leadless Packages
Detailed Surface Mount Guidelines for
Leadless Packages
Skyworks’ plastic encapsulated leadless style packages
are being offered on several products to reduce size and
weight and to improve application performance. These
packages are gaining acceptance in the industry and are
often referred to by such names as “QFN,” “LPCC,” “MLF”
and others, and conform to JEDEC outline MO-220.
0.65 (0.026)
0.50 (0.020)
0.25
(0.010)
4.20
(0.165)
3.20
(0.126)
2.79
(0.110)
0.33
(0.013)
TYP.
These packages use perimeter lands on the bottom of the
package to provide contact to the PCB. These packages
also have an exposed paddle on the bottom to provide a
stable ground for optimum electrical performance of
switches and attenuators, and an efficient heat path for
thermal performance for amplifier products.
0.20 (0.008)
1.60 (0.063) TYP.
DIMENSIONS IN mm (in.)
Mold Compound
Gold Wire
LEAD LENGTH OF LPCC
Down Bond
LEAD WIDTH
OUTSIDE OF PACKAGE
DIE
Lead
FOOTPRINT OF PCB LAND = LEAD LENGTH + 0.1 mm
Exposed Die Paddle
Figure 2. Surface Mount Land Pattern,
4 x 4 mm 16 Lead LPCC
Figure 1. Package Cross Section
Within are the suggested guidelines for layout of a PCB
and stencil for Skyworks’ 4 x 4 mm LPCC-16.
PCB Design Guidelines
For the lead/terminal solder pad design, it is
recommended to use a Non Solder Mask Defined (NSMD)
approach, but a small amount of solder mask should
remain between the pads to avoid solder bridging between
terminals. The PCB land width should match package pad
width. The PCB land length should be 0.1 mm greater than
the package pad length, with the extra area on the outside
of the package. See Figure 2.
4
The ground pad on the PCB should match the size of the
exposed paddle of the package and should be Solder
Mask Defined (SMD). The solder mask opening should
overlap the edges of the PCB ground pad by 0.065 mm
(0.0025") on all four sides. The recommended design gap
between the PCB ground pad and land pad is 0.15 mm
minimum to avoid solder bridging and shorting. When
space is available, a gap of 0.25 mm or more is preferred.
Plated thru via holes in the PCB ground pad should be
0.33 (0.013") in diameter and plugged. If via holes cannot
be plugged, it is recommended to cap the vias on the
backside of the board using solder mask material. This
should allow the vias to be filled with solder during reflow.
Skyworks Solutions, Inc. [781] 376-3000 • Fax [781] 376-3100 • Email sales@skyworksinc.com • www.skyworksinc.com
Specifications subject to change without notice. 10/02A
Suggested PCB Land Pattern Designs for Leaded and Leadless Packages
and Detailed Surface Mount Guidelines for Leadless Packages
Solder Mask Design
Solder Paste and Reflow Profile
Two types of stencil designs are used for surface mount
packages:
Because leadless packages have a low stand-off height
and small terminal pitch, a No Clean, Type 3 solder paste,
and a convection/IR reflow is recommended.
1. Solder Mask Defined (SMD): Solder mask openings
smaller than metal pads.
2. Non-Solder Mask Defined (NSMD): Solder mask
openings larger than metal pads.
NSMD is recommended for the perimeter I/O lands, as this
allows the solder to wrap around the sides of the metal
pads on the board for a reliable solder joint.
Sn63 (63% Sn, 37% Pb) solder is preferred because it is
a eutectic compound with a melting point of 183°C. The
reflow temperature in this case would be above 183°C for
30–60 seconds, with a peak temperature of 205–210°C.
Because the spacing between the ground pad and the
land pads can be small, SMD is recommended for the
ground pad to prevent solder bridging.
If a lead-free alloy is used, such as tin/silver or
tin/silver/copper, the melting point is 221°C and 217°C
respectively. In this case, the profile would be above
221/217°C for 30–60 seconds, with a peak temperature
of 230–240°C. Maximum temperature should not exceed
240°C.
A stainless steel stencil, 0.125–0.150 mm (0.005–0.006")
thick, is recommended for solder paste application. For
better paste release, the aperture walls should be
trapezoidal and the corners rounded.
A typical reflow profile is presented in Figure 4, which
could be used as a starting point. The actual profile used
will depend on the thermal mass of the entire populated
board and the solder compound used.
For the terminal lands, the stencil opening should be
0.05 mm larger than the PCB land (0.025 mm in each
direction).
<1.3˚–1.6˚C/Sec.
Temperature (˚C)
For the ground pad area, it is recommended to screen the
solder paste in an array of small openings rather than one
large opening. The total (cumulative) area of all the
openings should be approximately equal to 50% of the
total ground pad area. This will ensure good solder
coverage with fewer voids. See Figure 3.
250
200
<0.5˚–0.6˚C/Sec.
150
30–60
Sec.
<2.5˚C
Sec.
100
3
Minutes
Min.
2–4 Minutes Max.
50
Multiple Small Stencil Openings
(Total Area Approximately 50% of
Total PCB Ground Pad)
Preheat Flux Activation/ Reflow
Thermal Equalization
0
0
60
120
180
240
Cool
Down
300
Time (Seconds)
Figure 4. Typical Solder Reflow Profile
PCB Ground
Pad Boundary
Terminal Land
Stencil Opening
Figure 3. Recommended Stencil Design
Skyworks Solutions, Inc. [781] 376-3000 • Fax [781] 376-3100 • Email sales@skyworksinc.com • www.skyworksinc.com
Specifications subject to change without notice. 10/02A
5