PCBA Tech - Explaining skills of PCBA processing and manufacturing

PCBA processing technology introduction

PCBA processing technology has become increasingly mature, with a wide range of applications, and it plays a key role in various intelligent equipment today. In order for the circuit board to achieve the intended design function, in addition to the hardware in place, the matching support of the software or the program is indispensable, then the problem is here:

Programs can be run through IC, but how are they "moved" in? I believe many students have guessed it, and the answer is "burning". Burning, the process of moving the program into the internal storage space of the chip, generally divided into offline burning and online burning

Offline burning

Compatible with different packaged chips through various adapters, and only when the chip and the adapter are used together can the program be burned. The adapter itself is a precision fixture, and different chips and different packages require different adapters.

At present, the packaging of chips such as Emmc, which is widely used, is developing in the direction of miniaturization and planarization such as BGA and QFN, and the price of adapters of this type of packaging is not low.

If there is an error during the production test, and the production retrospective re-correction is performed, the chip needs to be removed from the adapter and re-programmed in accordance with the prescribed process, which is time-consuming, laborious, and costly. There will be some unexpected situations during PCB processing and production, such as insufficient temperature resistance of the circuit board, and the chip will be deformed when the chip is disassembled, which will invisibly increase the risk of scrap.

Online burning

Online programming uses the chip's standard communication bus, such as USB, SWD, JTAG, UART, etc. The interface is generally fixed, and there are fewer pins that need to be connected during programming. Because the interface communication rate is not high, the programming can be completed by using ordinary wires without high consumption.

Since online programming is performed by wire connection, if an error is found during production testing, the PCBA that has the error can be traced back immediately, and the program can be re-programmed without disassembling the chip. It not only saves production costs, but also increases the efficiency of programming.

More importantly, the production line is also developing towards automation. More and more manufacturers add ICT, FCT and other functional testing machines to the production line. The production method of using automatic fixtures and online programming can be omitted in the programming stage. Manual operation, burn directly after mounting the board, and then send the PCBA to the testing machine for testing. The entire production process is fully automated, which can greatly improve production efficiency.

Therefore, in PCBA processing, the advantages of online programming are significant, and it has become one of the important indicators in the industry to measure the process accuracy, production efficiency, cost, quality control, scale, and capital of PCBA manufacturers.

PCBA processing precautions

Auditing a PCB factory should not only pay attention to its scale and environment, but also pay attention to these key quality points. The grades of substrate materials range from A to C, and the prices vary greatly. The cleanliness management of the dust-free exposure workshop can also be known through the documents of a third-party testing agency. There are many factors that determine the quality of PCB. Among them, the copper coating process of substrate material, dust-free exposure, and copper coating as the key circuit board has extremely high requirements for consistency and uniformity. Solution replacement management must be standardized, and equipment maintenance must be in place. The copper coating process also needs to be summarized and improved repeatedly in practice.

What issues should be paid attention to when purchasing components?

Ensure that the components come from the original brand, which is critical to the packaging process, and can prevent batch defects from the source. Electronic manufacturing companies need to set up incoming material inspection positions (IQC) to check the consistency of incoming materials, and sample the appearance, component values, errors, etc. PCBA electronics manufacturing companies also need to continuously optimize their component supplier channels.

Surface mount process requirements for smt chip processing

In the SMT surface mount process, PCBA electronics manufacturing companies need to ensure that the solder paste printing is uniform and consistent, and the program design of the SMT machine is reasonable to ensure the placement yield of high-precision IC and BGA. AOI inspection and manufacturing process quality inspection (IPQC) are very necessary. At the same time, it is necessary to strengthen the management of feeding materials, and strict file management is required from material picking to stacking table.

How to test the PCBA board after it is processed?

PCB design engineers generally reserve test points on the PCB and provide corresponding test solutions to PCBA electronics manufacturers. In ICT and FCT tests, analyze the voltage and current curves of the circuit, as well as the results of the functional test of electronic products (with the help of some test racks), and then compare the test plans to establish the acceptance range, which is also convenient for customers to continue to improve .