SLAU857A May   2021  – July 2021 MSP430FR2476 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR2672 , MSP430FR2673 , MSP430FR2675 , MSP430FR2676

 

  1.   1
  2.   2
    1.     3
    2.     4
  3.   5
    1.     6
    2.     7
    3.     8
  4.   9
    1.     10
      1.      11
      2.      12
      3.      13
    2.     14
    3.     15
  5.   16
    1.     17
      1.      18
      2.      19
        1.       20
        2.       21
        3.       22
      3.      23
    2.     24
      1.      25
      2.      26
  6.   27
    1.     28
      1.      29
      2.      30
      3.      31
      4.      32
      5.      33
    2.     34
      1.      35
      2.      36
      3.      37
    3.     38
    4.     39
      1.      40
      2.      41
      3.      42
      4.      43
      5.      44
    5.     45
    6.     46
      1.      47
      2.      48
      3.      49
      4.      50
      5.      51
  7.   52
    1.     53
    2.     54
    3.     55
    4.     56
    5.     57
  8.   58
  9.   59

4.1.3 Mechanical Design Checklist

The main aspects of the mechanical structure that affect the touch sensitivity are coating, housing, and surrounding devices. Coating design mainly affects the capacitance change caused by finger touch. For a self-inductive solution, grounding the shell improves the noise immunity of the product, but it increases the capacitance to ground and reduces the sensitivity. For a mutual-capacitive solution, the grounding of the surrounding environment has little effect on the sensitivity. As capacitive touch is a sensitive device and also a source of interference, a grid ground plane is required for protection and isolation. Table 4-2 is a checklist of mechanical structure design.

Table 4-2 Mechanical Structure Design Checklist
NumberComponentRecommendation
1OverlayMaterialAvoid the use of conductive materials and conductive paints.
2Thickness10 mm or thinner, 2-3 mm is recommended, depending on the material and sensor size.
3CascadeAvoid gaps between the overlay and the buttons, use nonconductive adhesive materials.
4Metal shellIn the case of ensuring sensitivity, the shell should be grounded as much as possible to improve noise immunity.
5Surrounding devicesKeep the PCB with button function as far away as possible from any internal radiation noise source in the product.

Keep the PCB with button function as far away as possible from sensitive devices.

Keep the PCB with button function as far away as possible from the PCB with a lot of ground.