PCB Design Company explains PCB design skills for you

1. Familiar with the factory manufacturing process

Many PCB design engineers only know how to draw boards and pull lines. It is not surprising that PCB production steps and chemical processing processes are completely unknown. However, the lack of such practical knowledge often leads to no more complex design decisions for novice engineers.

Does design really need so complicated? Can't we use a larger grid to wiring, thereby reducing the cost of circuit board and improving reliability? Design other mistakes that novices make, as well as unnecessary small passage sizes and Blind Via and Buried Via. Those advanced pores are the weapons of PCB designers, but their high validity (Effectiveness). Although they are available tools, they do not mean that they must be used.

A blog post from PCB design expert Bert Simonovich talked about the problem of the proportion of the pores: "The length and width ratio of 6: 1 can ensure that your circuit board can be produced anywhere." For most designs, most designs As long as you think and plan a little, you can avoid those high -density (HDI) features and save costs and improve design.

Those ultra-small or single-end (Dead-Ended) pores for copper plating are required for copper-plated physics and fluid mechanics capabilities. Not all PCB foundries are good at. Remember, as long as there is a bad pass, you can destroy the entire circuit board; if you have 20,000 pores in your design, then you have 20,000 chances of failure. Unnecessary use of HDI to pass the holes, and the failure rate will soar immediately.

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2. Circuit can simplify design tasks

Sometimes just design a simple circuit board, and the schematic seems to be a waste of time; especially if you already have the experience of completing one or two designs. But for those who design PCB for the first time, drawing circuit diagrams will also be a difficult task. Jumping circuit diagram is a strategy often adopted by novices and design engineers with medium -level experience, but please develop your wiring from a complete circuit diagram that can be used as a reference, which will help ensure that your wiring link can be completed all complete. ; The following is the reason:

First of all, the circuit diagram is the visual presentation of the PCB circuit, which can convey the information of multiple levels; the sub -area of the circuit is divided into several pages of detailed drawing, and the corresponding parts of the function can be arranged in the neighboring position, regardless of its final physical layout. Secondly, because the circuit diagram symbol will indicate each pin of each component, it is easy to detect unpopular kicks; in other words, regardless of whether the formal rules of the circuit are described are followed, the circuit diagram helps you quickly use vision with vision quickly with vision Determine to ensure the integrity of the circuit.

If there is a circuit diagram as a basic template when designing PCB, it can simplify the wiring task. Use the circuit diagram symbol to complete the link, and at the same time, you do not need to repeatedly think of those links to overcome the ride challenge; in the end you will save the design and redo the design of the lane connection that is missing at the first revision.

Circuit map can simplify design tasks

3. Use an automatic wiring device but do not depend on

Most professional -grade PCB CAD tools have automatic wiring, but unless you design PCB very professional, the automatic wiring can only be used to make the design preliminary level; for the PCB circuit link You should still know how to complete the solution.

Automatic wiring is a highly configured tool. In order to give full play to their role, each task must be carefully set and consider the setting of the wiring parameters. In short, there is no proper basic general default value.

When you ask an experienced design engineer: "Which automatic wiring is best to use?" They would answer: "The things in the middle of the ears on both sides (eyes);" and they are serious. The process of wiring is more like an art like algorithms, which itself is heuristic, so it is very similar to the traditional backtracking algorithm.

The retrospective algorithm is very suitable for finding solutions, especially the paths such as maze or puzzle selection; but on an open and unlimited occasion, such as the PCB of the components in advance, the retrospective algorithm cannot be used to find optimization optimization Solution strong. Unless the constraints of the automatic wiring device are carefully fine -tuned by the engineer, the wiring finished product still requires the weakness in the results of the retrospective algorithm.

The size of the wiring is another problem point. The automatic wiring cannot be 100 % determined to determine how large you intend to pass online, so you can’t help you determine how wide the wiring; the result is that most automatic wiring workers have taken away by walking. The width of the line does not meet the specifications.

When you consider using an automatic wiring, first ask yourself: "After I set the constraints of the automatic wiring in the board, and even set the constraints for each wiring on the circuit diagram, how much time can I use it for me to use? Manual wiring? "The veteran of the design engineer will put most of the energy on the initial part layout. Almost half of the entire design time is committed to optimizing the component layout from the following three aspects:

▪ Wiring simplified -minimize the cross lines (Rat's NEST, or Wanda Wire, Rat Trace Network) and so on.

▪ The near -connection of the component — the shorter the winding, the better.

▪ Signal timing consideration.

Old predecessors often use mixed methods to wiring -manually perform key wiring, fix their position, and then use automatic wiring to process non -critical wiring; the automatic wiring area in the design helps to manage "out of control (out of control (out of control (out of control in the wiring algorithm ( "RunAWAY) state", this method can sometimes be good at the controlling of hand -handed wiring and the speed of automatic wiring.

Old predecessors often use the mixed method to wiring — hand -made key wiring, fix their position, and then use automatic wiring to process non -critical wiring;

4. Consider the size and current of the circuit board

Most people engaged in electronic design know that like a river walking along the river, flowing electrons may also encounter throat dot and bottlenecks; this is directly applied to the design of Automotive Fuse. Through the thickness and shape of the wiring (U -shaped bending, V -shaped bending, S -shaped, etc.), the fuse can be calibrated and melted at the throat point when the current overloads.

The shape of the word. At best, those wires will only slow down the signal transmission; the worst case is that they will melt at the resistance of the resistance like a car fuse.

Consider the size and current of the circuit board.

5. Avoid the risk of cracks

Sliver is a manufacturing error that can obtain the best management through the appropriate circuit board design ; in order to understand the cracking problem, we need to review the chemical etching process. Chemical etching is to decompose copper that is not needed, but if the part of the etched part is particularly long, thin, and shelled, those shapes are sometimes stripped before being completely decomposed; this cracks will float in the chemical solution. It may be randomly fell on another circuit board.

The risk that may also occur is that the cracks still stay on the original circuit board; if the cracks are narrow enough, the acid liquid pool may corrode enough copper below, so that the cracks are peeled out. So the cracks were sticking around the circuit board like a flag. In the end, it was inevitable that it fell on the board and caused other short circuits by other wiring.

6. Follow DRC

The setting of the automatic wiring is usually for design functions, and the design rules checker (DRC) is generally used to capture the design constraints of the manufacturer. Essence Most design teams will eventually establish a set of design rules, the purpose is to standardize the cost and maximum yield of the production of bare plates, and make the assembly, inspection and testing as consistent as possible.

In addition to being beneficial to design, these design rules -by maintaining the design within the predefined manufacturing restrictions -also help to establish consistency in the procurement department; if the price of the circuit board manufacturing is consistent, the procurement is usually purchased. It can reduce the number of specific PCB manufacturing protocols that need to be maintained.

In order to solve all these problems, many PCB design tools have been built in DRC -some tools call them "constraint managers" -son Once you set the DRC rules for the selected manufacturer, you must prepare the errors seriously.

The DRC tools are generally conservative in design. They also make mistakes when reporting possible errors, and you must be determined by you; to screen hundreds of "possible" problems, it will be cumbersome, but you have to do it anyway. The reason why your first stream is destined to fail in this question list. In addition, if your design trigger a large number of possible errors, it means that your wiring method needs to be improved.

Dave Baker, who has more than 20 years of rich experience, recommends: "Take time to understand and correctly set the restraint system provided by the wiring tool, and review all levels of constraints; It can also be confusing and dangerous. The wrong constraints can easily lead to defects or irreversible circuit boards. Error in the constraint settings may be limited to DRC or make it irreplaceable. "