The quotation for PCB circuit board production is given by the board factory. With the continuous progress of Internet technology, many board manufacturers now have online pricing of PCB circuit boards. However, the determinants of PCB circuit board quotation mainly include the following aspects:
1. PCB area (size)
Area refers to the size of the PCB design drawings. If it is a rectangle, it is length x width. If it is a circle or other irregular shapes, it shall be calculated according to the maximum shape range. Under normal circumstances, the material waste caused by the irregular shape should be converted into.
2. PCB batch size
The larger the batch, the lower the price spread across each board.
3. PCB board material
Sheet material is the core material of PCB manufacturers, and the board factory generally uses the sheet material of long-term cooperative suppliers by default. But for the PCB board with special requirements, the designer has to specify the sheet material, and the price will be different. For example, there is a rogers sheet used for microwave radio frequency, and its price is 10 times that of ordinary sheets. The commonly used sheets in general board factories include Shengyi, Kingboard, Guoji, Nanya, Longtai, Huake and so on.
4. Number of PCB layers
Single-sided, double-sided, four-layer, six-layer, eight-layer, generally the number of layers is even. The higher the number of layers, the higher the price, which increases exponentially.
5. Delivery time
Under normal circumstances, the production cycle of single and double-sided panels is 3 to 4 days. If it is particularly urgent, you can choose 48-hour rush or even 24-hour rush, but the cost will increase. If there is a problem with the design that needs to be clarified, start counting the time after confirming all the problems.
6. Do you need to use special technology?
Each factory will have its own process parameters. If your design exceeds the process capability of the board factory, they will have to carry out special control during production, and the production cost will increase. In addition, the following conditions will also affect the quotation.
(1) Plate thickness. The conventional thickness of the double-sided panel is 0.4, 0.6, 0.8, 1.0, 1.2, 1, 6, 2.0, 2.4 (unit mm). If other thicknesses are to be produced, the price will rise.
(2) The color of the solder mask ink. The circuit board is generally covered with a layer of ink, this layer of ink does not stick to the solder, which is called the solder mask. Green is the most common and most economical, so the solder mask is also called the green oil layer. Other colors are red, yellow, blue, white, and black, as shown in Figure 3-135. Among them, the black ink board is the most difficult to produce, and the cost will be high.
(3) Pad processing. Copper is easily oxidized in the air and affects welding, so the parts that need to be welded should be surface coated, which is also called surface treatment in some factories. Its processes include lead spray tin, lead-free spray tin, immersion gold, nickel-plated gold, OSP, immersion silver, etc. Figure 3-136 is the three most commonly used surface treatment methods.
Tin spraying is the most common process in the PCB industry, and it has the advantages of good solderability and low cost. The disadvantage is that the flatness is not good, especially when the window is opened in a large area, it is easy to appear uneven. Lead-free tin spraying is to meet the requirements of environmental protection, and the cost of this process is slightly higher.
Immersion gold is to use the displacement reaction to form a thin layer of gold at the weld, which has good flatness and good weldability.
Nickel-plated gold is firstly plated with nickel at the weld, and then gold-plated. It is characterized by wear resistance and is used for positions that need to be plugged and unplugged frequently, such as gold fingers and buttons.
OSP relies on the chemical reaction between the potion and the copper skin to generate an organic protective film. This film has anti-oxidation, thermal shock resistance and moisture resistance. OSP is generally used less.
Immersion silver means that a layer of silver is plated at the welding position, and this process is less used. Silver is easily oxidized and blackened in the air, and it is required to be welded within a specified time.
Figure 3-136 Three surface treatment methods of immersion gold (left), tin spraying (middle), and nickel-plated gold (right)
(4) Electronic testing. Electronic testing is used to detect whether there is an open circuit in each solder joint of the same network in the circuit, and whether there is a short circuit in each solder joint of different networks. Proofing and small batch boards are all tested with flying probes. We can think of flying probes as two test leads of a multimeter. They can move quickly and accurately position, complete the measurement of two points in a very short time, and connect the on-off state. Compare with the existing data, if the place that should be disconnected is connected, or the place that should be connected is disconnected, record it. A large number of boards are generally tested with a bed of needles, which requires the production of test fixtures. It is a parallel measurement method, and the test speed is fast, but the cost is high.
(5) The number of puzzle pieces. In order to save costs, two or more boards can be considered together in one design drawing and sent to the board factory. This method can save the board factory's engineering costs and film costs, but some board factories need to add board costs.
(6) Character color. Generally, the color of the words on the PCB board is white. If you want to make other colors, the cost will increase.
The more economical double-sided board method is that there are no special requirements for the sheet material, the board thickness is 1.6mm, green oil, tin spraying, white characters, and 100% electronic testing. Board size, batch, delivery date and number of panels will be determined according to the specific situation.
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