Overview, tutorials or basic information about the PCB manufacturing process.
People in the electronics industry involved in the PCB manufacturing process are very important. Printed circuit boards, printed circuit boards, are very widely used as the basis of electronic circuits. Printed circuit boards are used to provide a mechanical basis on which circuits can be built. So almost all printed circuit boards used in circuits and their designs are used in millions.
Although PCBs today form the basis of almost all electronic circuits, they are often taken for granted. However, the technology is advancing in this regard. Track size is reduced, the number of layers is increasing to accommodate the increased connectivity required, and design rules are being improved to ensure that smaller SMT devices can be handled and the soldering process used in production can be accommodated.
The PCB manufacturing process can be implemented in various ways and has many variants. Despite many small changes, the main stages in the PCB manufacturing process are the same.
PCB composition
Printed circuit boards, printed circuit boards, can be made from a variety of different substances. The most widely used form of glass fiber substrate called FR4. This provides a reasonable degree of stability under temperature changes and is not as severe as breakdown, although not being overly expensive. Other less expensive materials can be used for printed circuit boards in low-cost commercial products. For high-performance radio frequency designs, the dielectric constant of the substrate is important and requires a low level of loss, then PTFE-based printed circuit boards can be used, although they are more difficult to handle.
In order to make the tracks with the components in the PCB, first obtain the copper clad board. This includes the substrate material, usually FR4, and the usual copper cladding on both sides. The copper coating is connected to a thin layer of copper on the motherboard. This combination is usually very good for FR4, but the properties of PTFE make this more difficult, which increases the difficulty of PTFE PCB processing.
Basic PCB manufacturing process
With the bare PCB board selected and provided, the next step is to create the required tracks on the circuit board and remove the unwanted copper. The manufacturing of the PCB is usually achieved using a chemical etching process. The most common form of PCB etching used is ferric chloride.
In order to obtain the correct pattern of the track, the photographic process is used. Usually the copper of the bare printed circuit board is covered with a thin layer of photoresist. It then passes through a photographic film or photomask, specifying the required track exposure. In this way the image of the track is transferred to the photoresist. With this completed, the photoresist is placed in the developer so that only those areas of the track plate are covered in the resist.
The next stage in the process is to place the printed circuit board on the iron hydride etched area where there is no need for tracks or copper. Knowing the concentration of ferric chloride and the thickness of copper on the circuit board, it is placed into the amount of time required to etch the foam e-commerce. If the printed circuit board is placed in the etching for too long, then some definition is lost as ferric chloride will tend to weaken the photoresist.
Although most PCB boards are manufactured using photographic processing, other methods are also available. One is to use a dedicated highly accurate milling machine. The machine is then controlled to grind the copper away in areas where it is not needed. The control is obviously automatic, driven from a file generated by the PCB design software. This form of PCB manufacturing is not suitable for large quantities, but it is an ideal choice in many cases where very small quantities of PCB prototypes are required. Another method that is sometimes used on PCB prototypes is to print anti-etching ink on the printed circuit board using the screen printing process.
Multilayer printed circuit board
As the complexity of electronic circuits increases, it is not always able to provide all the connections needed just on both sides of the PCB being used. This is quite common when dense microprocessors and other similar boards are being designed. When this is the case, a multilayer board is required.
In the manufacture of multilayer printed circuit boards, although the same process is used, as a single-layer board, a considerable degree of precision and manufacturing process control is required. The boards are made by using much thinner individual boards, one for each layer, and then these are combined together to produce a monolithic circuit board. As the number of layers increases, each board must become thinner to prevent the finished board from becoming too thick. In addition, the registration between the layers must be very accurate to ensure that any holes are aligned.
To combine the different layers together the board is heated to cure the adhesive material. This may cause some problems with the warp. Large multilayer circuit boards can have a unique bend on them if they are not designed correctly. This can happen especially if, for example, one of the inner layers is a power plane or a ground plane. Although this in itself is good, if some reasonably significant areas have been unwound copper. This can build up strains within the PCB, which can cause warping.
PCB holes and through holes
Holes, usually called via holes or vias, require different layers in the PCB to be connected together at different points. It may also require holes to allow components to be installed on the PCB to set the wires. In addition, some fixing holes may be required.
Under normal circumstances, the inner surface of the hole has a copper layer so that they are electrically connected to the layers of the circuit board. These “plated through holes” are produced using a plating process. In this way, the layers can be connected.
Then the drilling is done with a CNC drilling machine, and the data is being provided from the PCB CAD design software. It is worth noting that reducing the number of holes of different sizes can help reduce PCB manufacturing costs.
This may be necessary for some holes only in the center of the circuit board, for example, when the inner layers of the circuit board need to be connected. These “blind holes” are glued together by the previous PCB layers to drill out the corresponding layers.
Solder plating and solder mask for printed circuit boards
When soldering on the PCB, it is necessary to keep the area protected by what is called a solder mask which should not be soldered. The addition of this layer helps to avoid unwanted short circuits caused by solder on the PCB board. The solder resists the polymer layer and protects the board from solder and other contaminants. The color of the solder mask is usually dark green or red.
In order to add components to the circuit board, lead or SMT soldering to the circuit board is easy, and the exposed parts of the board are usually “canned” or solder-plated. Occasionally the board or area may be gold-plated. If some copper fingers are used for edge connection, this may be applicable. Since gold will lose its luster, it provides good conductivity and it provides good connections at low cost.
PCB silk screen
It is often necessary to print text and put other small printed idents on the PCB. This can help in the identification of the board, and it also marks the component location faults in the help search, etc. The silk screen generated by the PCB design software is added to the circuit board, and other manufacturing processes have been completed after the bare board.
PCB prototype
As part of any development process, it is usually recommended to submit a prototype before full production. The same is true for printed circuit boards where PCB prototypes are usually manufactured and tested before full production. Usually the PCB prototype will need to be manufactured quickly as there is always pressure to complete the hardware design phase of product development. Because the main purpose of the PCB prototype is to test the actual layout, it is often acceptable to use a slightly different PCB manufacturing process because only a small amount will be needed on the PCB prototype board. However, it is always wise to keep as close as possible to the final PCB manufacturing process to ensure that some changes are introduced to the final printed circuit board by few new elements.
summary
The PCB manufacturing process is an important part of the production cycle of electronic products. PCB manufacturing adopts many new areas of technology, which enables the reduction in the size of the components and tracks used in order to carry out two significant improvements, and the reliability of the circuit board.