ADBS-A320 Datasheet, PDF (4/55 Pages) AVAGO TECHNOLOGIES LIMITED – Optical Finger Navigation

PCB Assembly Considerations
1. Surface mount the sensor and all other electrical
components into PCB.
2. Reflow the entire assembly in a no-wash solder
process.
3. Remove the protective kapton tape from optical
aperture of the sensor and LED. Care must be taken
to keep contaminants from entering the aperture.
Recommend not to place the PCB facing up during the
entire assembly process. Recommend to hold the PCB
first vertically for the kapton removal process.
4. Press fit the lens onto the sensor until there is no
gap between the lens and sensor, with force up to
a maximum 2.2kgf. Care must be taken to avoid
contaminating or staining the lens. The lens piece has
alignment posts which will mate with the alignment
holes on the sensor package.
5. Place and secure the optical navigation cover onto the
lens to ensure the sensor and lens components are
always interlocked to the correct vertical height. The
cover design has a foolproof feature to avoid wrong
orientation of the cover.
6. The optical position reference for the PCB is set by the
navigation cover and lens.
7. Install device top casing. There MUST be a feature in
either top casing or bottom casing to press onto the
sensor to ensure the sensor and lens components are
always interlocked to the correct vertical height.
Note: Rectangular shape pad on PCB or FPC should
match in size (1:1) to sensor center GND pad
Figure 3b. Recommended Customer’s PCB PADOUT and spacing
Non-Solder Mask
Define Area
Soldering Profile Information
Max rising slope
Preheat time 150 – 200° C, ts
Time above Reflow (T_L = 220° C)
Peak Temperature
0.0°C/sec to 3°C/sec
60 – 90 sec
50 – 100 sec
225 – 260° C
The recommended soldering profile is shown below.
TP
Max. Ramp - Up Rate = 3°C/sec
Max Ramp - Down Rate = 6°C/sec
TL
Tsmax
Preheat Area
tp
Tc -5°C
t
Tsmin
ts
Solder Mask
Define Area
Detail 1
Metal Pad
Solder Mask
(Not shown in Fig 3b
for clarity)
Figure 3c. Recommended Customer’s PCB PADOUT and spacing
25
Time 25°C to Peak
Time (second)
Figure 3a. Recommended reflow profile
4