Recently, Susie, one of my best friends, who has been a dressmaker for more than five years, complained about one of her customers to me that the customer blamed her for her so-called carelessness. The lady brought a design sketch to Susie who was expected to make a dress based on it. As a result, the finished product didn’t prove to be a satisfying one and Susie insisted that given design sketch had been strictly followed. The battle finally ended as Susie agreed to make another new dress since she didn’t want this one customer to spread bad reputations for her.
Susie usually tells me that ordinary customers know so little about design sketch that they always ignore the association between design file and finished product. Therefore, nowadays Susie spends much time in explaining leading details of design sketch to her customers before real work in order to minimize the misunderstanding.
Compared with dress making, PCB (Printed Circuit Board) fabrication is much more complicated since it is closely related with high tech. Additionally, the increasing demands for high speed and miniaturization lead PCB manufacturing towards fine lines and micro manufacturing. Along manufacturing line, PCB board is made based on PCB design files that are able to tell where and how each circuit runs, where components should be placed and how vias should be arranged for the fulfillment of corresponding functions.
As far as PCB designers are concerned, nothing is able to make them more excited except their seeing ideas successfully transformed into products. However, the way from PCB designer to PCB manufacturer is not difficult at all as long as both parties focus on critical and necessary points.
Elements to be Settled before PCB Design
• PCB size
PCB size is determined by finished product size that should be settled by PCB designer in the phase of electronic engineering (EE). PCB size doesn’t only include length and width of a board but contains PCB thickness as well.
• PCB layer count
PCB layer count plays a decisive role in PCB board complexity that further affects PCB manufacturing process.
• PCB material
The grade and attributes of PCB material determine PCB performance and cost, which is also reflection of requirement on electronic products.
• Surface finish
Surface finish determines complexity of circuit board fabrication and products’ attitude towards environment. During PCB design phase, it’s optimal for designers to get aware of surface finish. If you have a vague impression on surface finish or have no idea which type should be picked, this article will definitely give you a hand.
• Copper weight
Electronic products have been witnessing increasing significance of size and weight, which derives from current people’s expectations. Copper contributes a lot to the whole weight of PCB board, so PCB designers have to be aware of perfect copper weight that is both capable of running and saving cost.
In-process PCB Design
PCB manufacturers cater exclusively to PCB designers’ ideas by fully following through on PCB design files. As a result, PCB designers should learn to accurately express their thoughts totally through file language, detail by detail. In terms of PCB design file, circuit design, PCB layout and Gerber file generation contribute to majority.
• Circuit design
PCB designers are able to go through this task by circuit design software and each of PCB designers has his or her favorite PCB software. If you are a green hand, a well-thought-out PCB software survey is a necessity. The leading PCB design software includes:
√ Altium Designer
Comparison needs necessarily to be made so that the proper PCB design software can be picked up for the sake of high efficiency and capabilities. Once a favorite PCB design software is determined, you can use it to generate schematic file that describes how electricity runs in the system and what functions the system will fulfill.
• PCB layout & Gerber file
The same PCB design software can also be used to design PCB layout and Gerber files. However, different PCB design software features different generation steps of Gerber files. Circuit design talks about board functions more while PCB layout and Gerber file generation about PCB fabrication more. PCB layout and Gerber file are the direct reference of engineers belonging to PCB manufacturers.
PCB layout tells engineers where components should be placed on the board, what connections should be achieved between components and how all the board layers are distributed and connected with each other. Signal flow path should be clearly depicted on Gerber files and interference should be decreased as much as possible. In order to increase EMC (Electromagnetic Compatibility) of the whole circuit, digital modules and analog modules should be rationally distributed.
Now, it’s time to officially start to manufacture a real printed circuit board. Each professional PCB manufacturer should contain a department called DFM (Design for Manufacturing) that strives to determine whether a PCB designer’s idea can be practically transformed into a genuine product with their current technology and equipment.
As soon as DFM check has been completed with any uncertainty confirmed by both sides, the machine starts to run. It’s of great necessity for PCB designers to understand the whole process of PCB fabrication, some main steps at least, so that their design can never be beyond reach.
• Filming and printing
PCB design figures should be first printed on a clear film in order to acquire the complete shape and circuits depicted in design files. After film is done, the pattern can be printed on copper foil so as to make copper path feature guidelines.
Copper etching aims to maintain wanted copper while getting rid of unwanted copper. Through etching, copper path can be formed totally according to what is described in PCB design files.
• Via drilling
Association between layers is to some extent determined by vias or holes including through holes, blind vias and buried vias
• Layer up
Based on layer count of PCBs, as all layers are ready, it’s time to combine them together using prepreg. With all layers permanently combined, a real multilayer PCB was born.
• Solder mask
Solder mask plays a significant role in stopping copper from being soldered. The color of solder mask is actually the color we often see on a PCB.
• Electrical test
Any PCB board can never go out of the factory without its functions being examined. Electrical test assists in helping people to know that the finished PCB totally caters to the requirement and functions of PCB design.
Well, the furthest distance in the world is not between PCB designer and PCB manufacturer but when PCB designer has got a fabulous idea yet it can’t be correctly understood by PCB manufacturer. However, if PCB designers prepare their design files by detail and show them in a way that is totally understood by PCB manufacturer and PCB manufacturer strives to cater exclusively to their design, the distance won’t be long.
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