Murata XBSC Series Assembly page 2

XBSC/UBDC/UBSC/BBSC/ULSC 100 µm & 400 µm -
Assembly by soldering
Pad opening
The top surface of the Murata silicon capacitors are protected with a mineral passivation. The finishing of the contact
pads are in nickel gold (generally 5µm nickel and 0.2µm gold) conforming with the soldering process.
Murata recommends having an opening on the board which matches the pad of the capacitor (size, position and
spacing) – see figure 1. On the substrate, the metal layer can be larger than the varnish coating opening size but in
this case, the varnish coating opening has to be mirror with the pad size of the capacitor. No need to change the
metal landing pad of the PCB, only the opening in the varnish coating needs to be adjusted (see Figure 1). These
recommendations will improve the die placement, tilting and will avoid the contact between the solder paste and the
bare silicon die - see Figure 2.
Solder paste after reflow:
Assembly Note – Ref : ASNUBSC1.6
FBC-0003-01
Varnish
coating
Metal pad
Figure 1: Solder paste after reflow - Targeted
Varnish coating
Figure 2: Solder paste after reflow - Rejected
Rev 1.2
Rev. 1.6
2