DRM101 Datasheet, PDF (28/56 Pages) Freescale Semiconductor, Inc – Blood Pressure Monitor Using the Flexis QE128 Family

Hardware Description
Figure 3-2. Bottom Layer
3.10.1 Mechanical Characteristics
3.10.1.1 Conductor Width and Clearances
The PCB is a rectangle with a size of 6.45 inches by 4 inches with a thickness of 0.064 inch.
The trace widths and clearances for power lines and signal lines are in this table:
Class
Regular signals
Power
Width
10
20
Clearance
10
10
Lines that carry more current, such as the collector lines for the Darlington transistors, have a width of 15
mm. When line widths were determined, current values and copper thickness were taken into account.
Standard drill sizes were used for guaranteed manufacturability and ease of production.
3.10.1.2 Trace Angles
One source of RFI is an abrupt change of direction in a PCB track, which effectively looks like impedance
discontinuities and will radiate accordingly. For HCMOS designs it is important to ensure that 90-degree
track-direction changes do not occur. Also, from the mechanical point of view, a 90-degree angle is more
likely to be detached from the board.
Blood Pressure Monitor Design Reference Manual, Rev. 0
3-6
Freescale Semiconductor