RClamp3552T
Final Datasheet Rev 4.0
Revision Date 10/5/2016
www.semtech.com
6 of 9
Semtech
Assembly Guidelines
The small size of this device means that some care must
be taken during the mounting process to insure reliable
solder joints. The gure at the right details Semtech’s
recommended mounting pattern. Recommended
assembly guidelines are shown in Table 2. Note that
these are only recommendations and should serve only
as a starting point for design since there are many factors
that aect the assembly process. Exact manufacturing
parameters will require some experimentation to get the
desired solder application. Semtech’s recommended
mounting pattern is based on the following design
guidelines:
Land Pattern
The recommended land pattern follows IPC standards
and is designed for maximum solder coverage. Detailed
dimensions are shown elsewhere in this document.
Solder Stencil
Stencil design is one of the key factors which will
determine the volume of solder paste which is deposited
onto the land pad. The area ratio of the stencil aperture
will determine how well the stencil will print. The area
ratio takes into account the aperture shape, aperture
size, and stencil thickness. An area ratio of 0.70 – 0.75
is preferred for the subject package. The area ratio of a
rectangular aperture is given as:
Area Ratio = (L * W )/ (2 * (L + W) * T)
Where:
L = Aperture Length
W = Aperture Width
T = Stencil Thickness
Semtech recommends a stencil thickness of 0.100mm for
this device. The stencil should be laser cut with electro-
polished nish. The stencil should have a positive taper
of approximately 5 degrees. Electro polishing and
tapering the walls results in reduced surface friction
and better paste release. Due to the small aperture
size, a solder paste with Type 4 or smaller particles are
recommended. Assuming a 100um thick stencil, the
aperture dimensions shown will yield an area ratio of
approximately 0.75.
Recommended Mounting Pattern
Stencil Opening (220x460 mm)
Land Pad (200x400 mm)
All Dimensions are in mm.
Land Pad.
Stencil opening Component
1.000
.850
Table 2 - Recommended Assembly Guidelines
Assembly Parameter Recommendation
Solder Stencil Design Laser Cut, Electro-Polished
Aperture Shape Rectangular
Solder Stencil Thickness 0.100mm (0.004”)
Solder Paste Type Type 4 size sphere or
smaller
Solder Reow Prole Per JEDEC J-STD-020
PCB Solder pad Design Non-Solder Mask Dened
PCB Pad Finish OSP or NiAu
Applications Information
