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As we all know, PCB is the board without installing components, and PCBA is the board with assembled components. So after completing the production of PCB bare boards, PCB component assembly, and other processes, the core hardware part of an electronic product is ready. Then how is it going to realize the function of the design? For a person who will not use it, it is simply installed component boards only. Who is responsible for activating it?
In its successful completion of the hardware functionality of the detection and testing, it is necessary for software engineers and the team for its coding, burning program and debugging and other processes, the core body of the electronic product before the completion of the production, loaded with mechanical enclosure and external components, the finished product is complete.
This PCBA coding program belongs to one of the core functions of a finished product and therefore has a strong confidentiality. Software engineering is written for the completion of the program. How do we import the PCBA? Then you need to pass “burn-in“.
What is burning?
Burning refers to the program “carried” to the chip's internal storage space process, which is generally divided into offline and online burning.
Offline burning is through the adapter and different packages of the chip connection, the chip and the adapter with the use of the program can be burned. The nature of the adapter is similar to a precision fixture, different packages of chips need to be matched with different adapters. If there is an error in production testing, production is back to re-correction, and you need to disassemble the chip from the adapter, and re-burning by the prescribed process, consuming a large amount of manpower and material resources, the cost is high. In PCBA processing production, some unexpected conditions, such as the circuit board temperature height is not enough to disassemble the chip will cause deformation of the chip, invariably increasing the risk of scrap.
On-line burning using the chip's standard communication bus, such as USB, SWD, JTAG, UART, etc., the interface is generally fixed, and the burning needs to be connected to a small number of feet. Because the interface communication rate is not high, the use of general wire can be completed by burning, which will not produce high consumption. On-line burning is connected through the wire to burn the program, if the production test time finds the error, you can immediately back to the error PCBA, and re-burn can be, done without disassembling the chip. Not only saves production costs but also increases the efficiency of burning.
In terms of cost and fault tolerance, online burn-in is more advantageous than offline burn-in.
How to improve the stability of online burning?
(1) Reduce the communication frequency: communication frequency is an important parameter for information transmission, the higher the frequency the faster the transmission speed, but the attenuation of the signal will increase with the increase in frequency, so when the burn-in is unstable, if the burn-in speed is not high, you can reduce the communication frequency appropriately to increase the stability of the burn-in.
(2) Try to shorten the length of the signal line: high-frequency signal transmission by the transmission distance is greatly affected by the distance, the farther the attenuation will be the greater the distance, which leads to burning instability. We can burner burner interface layout in the fixture signal input port from the nearest position, and try to shorten the length of the entire signal line.
(3) Select the conductive ability of the signal line: the integrity of the signal transmission and the line material, length, and thickness, you can choose a thicker, more conductive line, good material can reduce internal resistance, reduce signal loss, such as pure copper, gold-plated wire, silver-plated wire and so on.
(4) to burn the signal line to increase the shielding layer to prevent electromagnetic interference. Burner through the burner signal line on the chip burner, burner high-frequency signals are more sensitive to electromagnetic interference. Burning the environment for the general factory floor, and high-power equipment, makes electromagnetic interference more serious, to reduce electromagnetic interference, we can burn the signal line to increase the shielding network or select the shielding function of the line, such as shielded cable, network cable, etc..
(5) in the key signal line connected to the pull-up, pull-down resistor. Sometimes the burner burner interface itself is not enough to drive the ability will also lead to the burner is not stable, then you need to add the appropriate interface signal line pull-up or pull-down resistor to enhance the driving ability.
(6) Replacement of a more stable burner: The burner internal circuitry does not have strong anti-jamming ability or the burner interface circuit driveability is not enough, which can lead to burning instability. In this case, it is best to choose another burner with higher stability.
iPCB is committed to providing every customer with excellent PCB and PCBA hardware production, for you to solve the problem of the hardware module before the software burner.