PixArt Imaging Inc.
ADBS-A350 Optical Finger Navigation
Overview of Optical Sensor Assembly
Soldering Profile
PixArt Imaging provides an IGES file drawing describ-
The recommended soldering profile is shown below.
ing the cover plate molding features.
tp
TP
The components interlock as they are mounted onto
defined features on the cover plate.
Tc -5°C
Max. Ramp - Up Rate = 3°C/sec
Max Ramp - Down Rate = 6°C/sec
TL
t
The ADBS-A350 sensor is designed for surface mounting
on a PCB, looking up.There is an aperture stop and features
on the package that align to the lens.
Tsmax
Tsmin
Preheat Area
ts
The lens provides optics for the imaging of the surface as
well as illumination of the surface at the optimum angle.
Features on the lens align it to the sensor and cover plate.
Contamination must be kept away from the lens. During
assembly process, it is recommended to use a minimum
of a 10K clean room environment or equivalent laminar
flow workbench.
25
Time 25°C to Peak
Time (second)
Figure 3a. Recommended reflow profile
PCB Assembly Considerations
1. Surface mount the sensor and all other electrical com-
ponents into PCB.
2. Reflow the entire assembly in a no-wash solder
process.
3. Remove the protective kapton tape from optical aper-
ture 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 assem-
bly 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 maxi-
mum 2.2 kgf. Care must be taken to avoid contaminat-
ing or staining the lens. The lens piece has alignment
posts which will mate with the alignment holes on the
sensor package.
Figure 3b. Recommended Customer’s PCB PADOUT and spacing
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.
Profiling Information
Max rising slope
0.0°C/sec to 3°C/sec
60 – 90 sec
Preheat time 150 – 200° C, ts
Time above Reflow (TL = 220° C)
Peak Temperature
50 – 100 sec
225 – 260° C
Figure 3c. Recommended Customer’s PCB PADOUT and spacing
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
PIXART [ PIXART IMAGING INC. ]
