How o draw best design for manufacturing and assembly?

Importance of design for manufacturing and assembly in the manufacturing process

Paying attention to design for manufacturing and assembly goes beyond the aesthetics of board assembly. Of course, choosing the best components, planning the circuits and having a good software planning is very important for the functioning of the hardware, but if the board in question doesn’t have a good layout, all this is easy to ruin. Therefore, some good practices need to be taken into account.

TIPS FOR PCB DESIGN

Small details regarding the position and size of components can make all the difference. A perfect board is one that performs its functions well for a long time. Here’s what you need to consider.

The role of proper design is vital in pcb industry. Let me explain why? In modern era, there is need of electronics which need high temperature resistance. PCB manufacturers need to design and assemble pcb boards according to the requirement.

PHYSICAL CHARACTERISTICS OF THE BOARD

When performing design for manufacturing and assembly, take into account the size of the tracks. It is important to keep in mind that they have resistance, that is, they have voltage drops, dissipate energy and increase the temperature when current flows through them. As these physical properties cannot be modified, this needs to be compensated for in the layout.

 

Ideally, use a specific calculator for track widths and predict an extra 5ºC in temperature. If there is extra space on the board then it even better. Increasing the safety margin can be useful for your project.

TEMPERATURE CONTROL

Many factors influence the heating of the plate and this directly influences its proper functioning. This is a point of attention for design for manufacturing and assembly because some actions need to take. In addition to the safety margin for the width of the tracks, if the board has multiple layers remember that there is a temperature difference between them. The outer layers are cooler.

Why thermal vias are common?

An interesting guideline is to put extra copper on the surface where the components will be placed to provide extra surface area to dissipate heat more efficiently. Also use Thermal Vias for heat dissipation, especially when the PCB is mounted in a chassis, as it is able to help it dissipate heat.  Another simple tip is to keep components that are sensitive to heat away from other components that generate heat.

LOOP SIZE

A board that has very large loops is subject to instabilities in operation, especially if they are high frequency loops. Therefore, when performing design for manufacturing and assembly, the ideal is that these cycles are as small as possible. If possible, design them so that they are surrounded by a grounded plane.

DECOUPLING CAPACITORS

The position of the capacitors is important to the PCB design because the proper functioning of the board requires them to be close together. Otherwise, there will be unwanted inductances. To increase their efficiency, the decoupling capacitors should be as close as possible to the power pins and connected to the ground plane of the integrated circuits. Prefer to use multiple leads of the capacitor pins for a ground plane, this can reduce the inductance.

AVOID NOISE

Some design for manufacturing and assembly errors result in unwanted noise. To prevent them from happening, one of the tips is to place tracks close together and tie the two together using a capacitive effect, especially when there is frequency. Take care to keep them away from other trails that might generate noise. Another precaution is not to place noisy routes close to signals that need to be silent.

Placing a grounded plane directly under tracks can lower impedance and help eliminate noise. The content in the series of articles about high speed design pcb on PCBVIET does not try to provide a complete overview of high speed design for manufacturing and assembly, because there are countless excellent and highly specialized documents and books on this topic.

What is high-speed design for manufacturing and assembly?

A PCB design is said to be a high-speed PCB design when it has very fast switching components, so fast that the leveling is completed before the signal can reach its destination. For example a signal such as the flow of water in a loop with a water valve at the top, and the high/low (1/0) state of the signal depends on whether the water lock is open or closes.

 Case 1:

To understand design for manufacturing and assembly look as the water pressure at the loop is P. The loop is closes to open, equivalent to the logic switch from 0 to 1. This process takes a period of time T and the water has flowed out to the loop head to get water.

Ø Case 2:

The water pressure at the loop is still P. The loop closes to open, equivalent to the logic switch from 0 to 1, this process also takes a period of time T’ with T’ many times smaller. Compared to T, is so small that before the water could flow out to the top of the loop, the water valve was closes.

What is the same case with High-speed pcb?

For better understanding of v design for manufacturing and assembly look these lines. In fact with high speed components, some documents even use the term “Fast edges” for high speed components. When a signal has “fast edges” it changes the way energy flows through the circuits. Basically with low speed signals you think of it as water flowing in a pipe and the friction of the water against the pipe.

Summary

For DC circuits or circuits with low switching frequency you can find out the resistance of the line and ensure that the power loss along the way does not affect the performance or signal. It is not so simple in a high speed design. Because at high speed electrons pass through the circuit lines, part of the energy transferred also includes the electromagnetic energy around the circuit due to the electrons themselves.