Assembly Instructions for SCA6x0 and SCA10x0 series
TN71
5
Printed Circuit Board (PCB) Level Guidelines
5.1 Recommended PCB pad layout
For optimal soldering and solder joint reliability results of VTI's DIL component, the PCB terminal
pads should be designed larger than the package leads. Reference dimensions for the land pad
design are presented in Figure 7. Note that this is only an example and e.g. much narrower pads
can be used and also the length can be different.
REFERENCE PCB LAYOUT FOR SCA6x0
REFERENCE PCB LAYOUT FOR SCA10x0
Figure 7: PCB pad lay-out for the DIL-8 and DIL-12.
VTI's DIL packages can be soldered on commonly used substrates, e.g. FR-4, ceramic etc. The
pad metallization should be solder wettable in order to assure good quality solder joints. For fine
pitch assembly, the quality of plating is important. Generally used circuit board finishes for fine pitch
SMD soldering are NiAu, OSP, Electroless-Ag and Electroless-Sn.
5.2 Solder paste and Cleaning process
The DIL package can be soldered with lead-free SAC (tin-silver-copper) solder. The SAC solder
paste composition should be near eutectic. The melting point of lead-free SAC solder can vary
between 217–221ºC, depending on the composition of solder alloy. In order to guarantee full RoHS
compatibility lead-free solder should be used for the soldering of VTI's DIL component. Also
traditional eutectic SnPb solder can be used for soldering the DIL packages if a lead-free process
is not required. With the eutectic SnPb solder, the melting point is 183°C.
A no-clean solder paste should be used, since the cleaning process is not recommended. The
metal lid on the pre-molded package is not fully sealed and there is a risk that cleaning fluids might
penetrate inside the package. If cleaning is used, user must validate that the process does not
decrease the performance or reliability of the component. Ultrasonic agitation is strictly
prohibited for VTI's MEMS components. Ultrasonic might destroy the MEMS structures.
The solder paste which is used must be suitable for printing it through the stencil aperture
dimensions. Type 3 paste is recommended (grain size 25-45µm).
VTI Technologies Oy
www.vti.fi
5/12
Rev.1.0
VTI [ VTI TECHNOLOGIES ]
