HDC1008 Datasheet, PDF (19/30 Pages) Texas Instruments – Low Power, High Accuracy Digital Humidity Sensor

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11 Layout
HDC1008
SNAS649B – OCTOBER 2014 – REVISED DECEMBER 2015
11.1 Layout Guidelines
The Relative Humidity sensor element is located on the bottom side of the package. It is positioned between the
two rows of bumps.
It is recommended to not route any traces below the sensor element. Moreover, the external components, such
as pull-up resistors and bypass capacitors need to be placed next to the 2 rows of bumps or on the bottom side
of the PCB in order to guarantee a good air flow.
11.1.1 Surface Mount
Two types of PCB land patterns are used for surface mount packages:
1. Non-solder mask defined (NSMD)
2. Solder mask defined (SMD)
Pros and cons of NSMD and SMD:
1. The NSMD configuration is preferred due to its tighter control of the copper etch process and a reduction in
the stress concentration points on the PCB side compared to SMD configuration.
2. A copper layer thickness of less than 1 oz. is recommended to achieve higher solder joint stand-off. A 1 oz.
(35 micron) or greater copper thickness causes a lower effective solder joint stand-off, which may
compromise solder joint reliability.
3. For the NSMD pad geometry, the trace width at the connection to the land pad should not exceed 2/3 of the
pad diameter.
( 0.263)
METAL
0.05 MAX
0.05 MIN
METAL
UNDER
MASK
SOLDER MASK
OPENING
NON-SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK
DEFINED
SOLDER MASK DETAILS
NOT TO SCALE
Figure 17. Solder Mask
( 0.263)
SOLDER MASK
OPENING
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