PCB Prototype China Printed Circuit Board Problems

- Oct 19, 2019-

Although PCB prototype China has been precipitated for more than 20 years, due to the lag of SMT teaching in China, pcb prototype China electronic product development and design personnel are generally unfamiliar with SMT production equipment and manufacturing processes, and lack of practical experience.Leading to designed product can be less productive, affecting product reliability and production efficiency. The following are common problems and solutions in printed circuit board design.

 

(1) The reference mark (Mark), PCB outline and size, pcb positioning hole and clamping edge setting are incorrect

1 The reference mark (Mark) is made on the grid of the earth, or there is a solder mask around the mark figure. Due to the inconsistent and reflective image, the mark is not recognized and frequently stopped.

2 When the guide rail is transmitted, due to abnormal outline of PCB, the PCB size is too large, too small, or the PCB positioning hole is not standard, which makes it impossible to load board and cannot implement the machine mounting operation.

3 Components are placed near the positioning hole and the clamping edge, and only manual subsidies can be used.

4 The components in the vicinity of the panel slot and the notch are not placed correctly, and the components are damaged when the board is cut.

(2) Pcb prototype material selection, pcb thickness and length, width and size are not suitable

1Because the PCB material selection is not suitable, it has been deformed before mounting, resulting in a decrease in mounting accuracy.

2 PCB thickness and aspect ratio are not suitable for deformation during placement and reflow soldering, producing soldering defects easily, and easy to damage components. Especially when welding BGA, it is easy to cause virtual welding.

 

(3) Common design problems of BGA

Figure 1 (a) is an example of through-hole, solder mask, wire and pad size irregularities, Figure 1 (b) is an example of pad shape is not standardized, part of the pad is covered by solder mask, Figure 2 (c) is A large-scale grounding pad in the middle which is directly separated by a solder mask. The large heat capacity causes uneven reflow temperature and various soldering defects.

is an example of through-hole, solder mask, wire and pad size irregularities

is an example of pad shape is not standardized, part of the pad is covered by solder mask


is A large-scale grounding pad in the middle which is directly separated by a solder mask



(4) In the reflow soldering and wave soldering mixing process, the BGA via holes are not blocked and cause secondary tin melting

(5)   Inappropriate componnet options or component packaging options

(6)   Since the packaging of optional components and components is not configured according to the placement machine feeder, it is impossible to mount with the placement machine.

As can be seen from the above design problem examples, the PCB design problem is difficult or even impossible to solve in the production process. It can be solved immediately by remedial measures or through repair, but it will cause different degrees of loss to product quality, cost and benefit. .


 

 


Previous:Basic requirements for components and printed boards of wave soldering processes Next:Prevent defect generation by monitoring pcb process variables