PCB Tech - Features of PCBA surface mount components

What are the risks of PCBA foundry materials? It is difficult to confirm the authenticity of the materials, the procurement cycle is unstable, the maintenance is difficult, the capital and other risks; there are many characteristics of the surface mount components in the PCBA processingplant, such as less parasitic capacitance and parasitics of the components Inductance, thereby improving the high-frequency characteristics, is conducive to increasing the use frequency and circuit speed, and then I will introduce it to everyone.

1. What are the risks of PCBA foundry materials

1. It is difficult to confirm the authenticity of materials

As PCBA foundry manufacturers are responsible for the overall manufacture of electronic components and PCBs, some electronic processing plants pursuing profit may purchase some counterfeit and shoddy materials in order to reduce production costs. In this case, the quality of the material can be ensured by specifying the material supplier and providing the original certificate of the material.

2. The procurement cycle is unstable

In the entire production cycle of PCBA processing, material procurement is the most unstable, especially when the components used by the customer are scarce, not common supplies, or the demand for components is large, and the foundry has no inventory and needs to take the way of ordering At this time, uncontrollable factors will occur.

3. Difficulty in maintenance

If the PCBA foundry manufacturer does not have strong repair capabilities, it will cause difficulty in product repair and prolong the repair cycle, which will eventually affect the delivery time of the product and cause relatively large losses to customers.

4. Capital risk

The PCBA foundry production model requires processing manufacturers to help customers purchase all materials. Customers need to pay an advance payment, usually 70% of the total payment, and then the manufacturer starts to purchase materials, carry out the PCBA processing production process, and finally, when the product is shipped The customer pays the remaining 30%. As we all know, the value of PCBA OEM service is generally relatively high, and the transaction amount is relatively large. In the process of cooperation between the two parties, defaulting on the accounts will easily lead to the break of the company’s funds, thus increasing many uncontrollable risks.

PCBA processing plant

Second, the characteristics of surface assembly components in PCBA processing plants

1. On the electrodes of SMT components, some welding ends have no leads at all, and some have very small leads; the spacing between adjacent electrodes is much smaller than the lead spacing of traditional dual in-line integrated circuits (2.54mm), IC's pin center distance has been reduced from 1.27mm to 0.3mm; in the case of the same integration, the area of SMT components is much smaller than that of traditional components. Chip resistors and capacitors have been reduced from the early 3.2mm*1.6 mm is reduced to 0.6mm*0.3mm; with the development of bare chip technology, BGA and CSP high-pin-count devices have been widely used in production.

2. SMT components are directly mounted on the surface of the printed circuit board, and the electrodes are soldered to the pads on the same side of the smt components. In this way, there are no pads around the through holes on the PCB printed circuit board, which greatly improves the wiring density of the printed circuit board.

3. Surface mounting technology not only affects the area occupied by wiring on the printed circuit board, but also affects the electrical characteristics of devices and components. No leads or short leads reduce the parasitic capacitance and parasitic inductance of components, thereby improving high-frequency characteristics, which is conducive to increasing the frequency of use and circuit speed.

4. The shape is simple, the structure is firm, and it is closely attached to the surface of the PCB printed circuit board, which improves the reliability and shock resistance; there is no lead bending or wire trimming during assembly, and the insertion element is reduced when the printed circuit board is manufactured. The through hole of the device: the size and shape are standardized, and the automatic placement machine can be used for automatic placement. The efficiency is high, the reliability is high, it is convenient for mass production, and the overall cost is low.

5. In the traditional sense, surface mount components do not have pins or have short pins. Compared with plug-in components, the solderability testing methods and requirements are different, and the entire surface components can withstand higher temperatures. However, compared with DP pins, surface-mounted pins or terminals can withstand lower temperatures during soldering.