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Application Note
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P-TSLP-2-1/P-TSLP-3-1
Recommendations for the Board Assembly
T h e t a r g e t of this document is to provide guidelines for our customers to successfully introduce Infineon's lead-
less packages P-TSLP2-1 / P-TSLP-3-1 into production. This includes recommendations for board pad design, stencil lay-
out, component placement, and soldering process. Generally standard SMT equipment and processes are suitable for
the board assembly of all P-TSLP packages.
The Packages P-TSLP-2-1 and -3-1
The Plastic-ThinSmallLeadlessPack-
a g e is one of the smallest packages for diodes and tran-
sistors available today.
A comparison with the SOT23 (see Figure 1) shows its
space-saving capabilities for all space and height critical
board assembly applications.
The P-TSLP-2-1 is a diode package with two terminals,
which are of the same size. The P-TSLP-3-1 is a transistor
package with three terminals.
The P-TSLP is a GREEN PACKAGE, that means it con-
tains no halogenides and no lead. It is compatible with all
Pb-free and Pb containing solder pastes.
For further information about the package dimensions,
the marking, the packing and other general information,
please observe our package information book or the infor-
mation about packages on our homepage
(www.infineon.com).
Figure 1
Comparison between P-TSLP-2-1/P-TSLP-3-1
and a SOT23 package
Board Pad Design
The solder pads have to be designed in a way
to ensure optimum manufacturability and reliability. Gen-
erally two basic types of solder pads are commonly used
for area array packages:
■"Solder mask defined" (SMD) pad: The copper pad is
larger than the solder mask opening above this pad.
Thus the land area is defined by the opening in the sol-
der mask.
■"Non solder mask defined" (NSMD) pad: Around each
copper pad there is solder mask clearance.
Because solder mask between the pads of the P-TSLP-
2-1 and -3-1 can cause tilted devices, the solder mask
opening should be larger than the outline of the device
(opening = outline + clearance). Therefore SMD pads are
not useable. NSMD pads generally provide more space for
routing and result in a higher solder joint reliability (also
the side walls of the lands can be wetted by the solder,
which results in less stress concentration).
Therefore this type is recommended for the P-TSLP-2-1
and -3-1.
The copper pad dimensions which have been tested
up to now are shown in Figure 2.
The solder pads must have good wettability to eutectic
solder. Electroless NiAu plating is a common surface finish
and proven to be suitable for P-TSLP assembly.
0.6
1
0.15
0.225
0.6
1
0.3 0.350.35
0.350.35 0.3
Figure 2
Recommendation for optimum pad design
(non solder mask defined pad)
Published by Infineon Technologies AG
Solder Paste Printing Process
T h e s o l d e r p a s t e deposited on the printed cir-
cuit board by stencil printing has to be of eutectic or near
eutectic composition (e.g. 63Sn37Pb, 62Sn36Pb2Ag or
lead free 95.5Sn3.8Ag0.7Cu). A no clean solder paste is
preferred, because cleaning under the soldered P-TSLP-2-
1/P-TSLP-3-1 may be difficult. The paste must have the
printing capability for the pitch 0.8 mm, or pitch 0.65 mm,
respectively (typically type 3 paste; to ensure a uniform
deposition of the solder paste a type 4 paste is not a dis-
advantage).
A stencil thickness between 120 µm and 100 µm is rec-
ommended, to ensure a uniform and high solder paste
transfer to the PCB.
Typical dimensions of the stencil apertures are shown
in Figure 3.
For applications with a large displacement between
stencil and PCB (e.g. FR4, ceramic) of more than ca. 100
µm, this process may not be reliable for the P-TSLP- 3-1. In
this case the solder deposition should be carried out for
example by a solder dispenser.
0.2
0.925
0.45
0.375 0.275
0.45
0.94
0.17
0.32 0.35 0.28
R 0.1
Figure 3
Recommendation for the stencil layouts. The rounded
holes in the case of the two small pads of the P-TSLP-3-1
are used in order to have a better solder transfer
Placement of Components
G e n e r a l l y t h e P - T S L P can be placed with a wide range of placement systems.
The following remarks are important:
■On large boards especially, local fiducials, close to the device, can compensate tolerances of PCB (e.g. FR4, ceramic).
■Vision systems with pad recognition and alignment with regard to the pad locations (in contrast to outline centering)
are typical for the placement of such packages.
Reflow Soldering Process
Generally all standard reflow solder-
i n g p r o c e s s e s (vapour phase, convection, infrared)
and typical temperature profiles used for fine pitch
devices are suitable for board assembly of the P-TSLP.
Wave soldering is not possible. At the reflow process each
solder joint has to be exposed to temperatures above sol-
der liquidus for a sufficient time to attain the optimum sol-
der joint quality, whereas overheating the board with its
components has to be avoided. Using infrared ovens with-
out convection special care may be necessary to assure a
sufficiently homogeneous temperature profile for all sol-
der joints on the PCB (especially on large, complex boards
with different thermal masses of the components) includ-
ing those under the P-TSLP. The most recommended types
are therefore forced convection or vapour phase reflow.
Nitrogen atmosphere can generally improve solder joint
quality as for soldering of leaded SMD devices, but is nor-
mally not necessary for the P-TSLP.
Figure 4 shows a typical forced convection reflow pro-
file, which is suitable for soldering the P-TSLP-2-1 and -3-1.
The temperature profile also has to be within the specifica-
tion of the used solder paste, and depends on the board
and the oven.
For typical Pb-free reflow soldering (e.g. with SnAgCu)
peak temperatures up to 260°C are used. Figure 5 shows a
corresponding reflow profile.
T
< 2.5 ˚C/s
240 2800
0
50
8040 160120 200 320s
t
˚C
100
150
200
300
250
Preheating Zone 170 s
Soaking
Zone
60 s
Reflow
Zone
50 s
Peak Temp.
225 ˚C
T
< 2.5 ˚C/s
2400
0
50
8040 160120 200 320280 s
t
˚C
100
150
200
300
250
Preheating Zone 165 s
Soaking
Zone
75 s
Reflow
Zone
90 s
Peak Temp. 260 ˚C
more than 250 ˚C, 35 s
Figure 4
Typical forced convection reflow profile suitable for P-TSLP-2-1/
P-TSLP-3-1. (example for solder paste Litton Kester R256)
Figure 5
Typical forced convection reflow profile suitable for
P-TSLP's lead free soldering
Ordering No. B000-H0000-X-X-7600
Printed in Germany
PS 09010. NB
www.infineon.com
