Key Points of Tablet PC PCB Design and GPS Design Matters

Key Points of Tablet PC PCB Design and GPS Design Matters

PCB assembly and PCB processing manufacturers explain the key points of tablet PC PCB design and GPS design

1. Side keys, TP, screen, headset, DC, battery, USB and other connectors should be cleared as soon as possible to prevent errors

2. All connectors such as screen, camera and touch screen are easy to reverse direction. When changing the layer of connector, it is necessary to change the position 180 degrees

3. If the parts are laid on the first layer, the second layer is the main ground, and the third layer is the copper layer for power supply. The lines shall be laid on the surface layer first, and the rest shall be laid on the third layer, and then on the second layer. The principle of the layer is to ensure the integrity of the copper layer for power supply and the layer, and the middle of the second layer shall be avoided as much as possible

4. DC-DC circuit unit, the components of each unit are placed on the same side; The input passes through the capacitor first, the output capacitor is close to the inductor, the feedback loop is far away from the inductor for interference prevention, and the input is directly connected with the output filter capacitor and the IC ground wire

5. The output line of audio power amplifier shall be isolated to prevent interference with other circuits

6. NAND FLASH has a great opportunity to use manual welding. Small parts need to be avoided, and two short circuit test points should be left on the data line

7. The audio decoding chip is difficult to be packaged and soldered as recommended, and the length of the bonding pad needs to be extended by 0.2MM

8. DC-DC circuit unit, the components of each unit are placed on the same side; The input passes through the capacitor first, the output capacitor is close to the inductor, the feedback loop is far away from the inductor for interference prevention, and the input is directly connected with the output filter capacitor and the IC ground wire

9. The HDMI signal frequency will reach more than 100M. The signal difference should be handled well. The signal processing chip and connector should be placed on the same side as far as possible

10. The side key fixed foot pad is easy to fall off and needs to be reinforced with copper

11. The device silk screen is divided into two layers, some at the top layer and some at the bottom layer. It should be unified to prevent missing silk screen

Several Important Points for Attention in GPS Design

1. The most important is radiation interference, which is generally far away from placement+shielding+filtering

2. GPS related important elements shall be placed next to GPS as far as possible; If it is a chip, it should be placed nearby

3. The signal channel shall comply with impedance matching. It is better to surround the ground and have a certain space with the surrounding parts

4. Conducted interference, which can generally be handled by means of series termination resistance

5. Large size antenna shall be used as far as possible in structural design to enhance signal acceptance

6. A certain space shall be kept around the antenna to avoid shielding the signal, and the receiving surface of the GPS antenna shall be higher than the surrounding parts to prevent affecting the receiving angle

7. The reliable materials shall be selected as far as possible; For example, it is better to select LDO with high noise rejection ratio, greater than 65; The resistance capacitance inductive element of the signal channel shall be of high frequency; The crystal oscillator with compensation shall be selected, which must be placed close to the chip; LNA or SAW components must be selected with small NF; The key elements defining the network in the circuit shall be those with high accuracy. For example, the reset circuit shall use resistance capacitance mode, which shall be of high accuracy as far as possible to prevent the occurrence of failure to reset under specific conditions.

As long as we take these aspects into consideration when designing structures and circuits, the products will not be too bad; Among the customers I often visit, many of them do not pay attention to them, which leads to unsatisfactory results. Generally, the results of the relevant improvement measures I provide can reach an acceptable state. PCB assembly, PCB design, and PCB processing manufacturers explain the key points of tablet PC PCB design and GPS design.