Programming assembled PCBs are standard. After production, there are several different ways to program the device. The process mostly depends on the assembly run volume and the form factor for the device. All of these methods have their own merits and demerits that we will be discussing in this article.
If you can plan the method through which you will be programming the IC before the estimated release date of the Printed Circuit Board Assembly or PCBA, then it will end up saving you a lot of money and time.
（Caption: PCB programming during PCBA processing ）
Contents
1. The main Obstacles Encountered in PCB Programming
- Some of the programming devices and fixtures can have a lead time.
- When the PCB can not be determined in advance, whether to support the chip programming software used will encounter a common problem.
- Any difference in the part number suffix could result in different voltages in the pin or different timing parameters in the programming PCB board algorithm.
Planning will guarantee that you have ordered all the necessary fixtures and confirmed the programming software's compatibility long before the assembly start date has arrived. Otherwise, you will be halting the assembly release date until all the parts are programmed. It can become extremely costly if you want to expedite the PCB fabrication and get stuck in putting the complete assembly on hold.
2.PCB Programming ICs: From the Factory
The easiest way this can be done is by getting ICs programmed from the manufacturer beforehand. You can also do this from any of the distributors who sell the parts. The Mouser and Gigi Key have offers for programming at a much lower price. They also provide an additional service for the same at discounted rates. When you have the ICs preprogrammed from the manufacturer or distributor, you no longer have to program them at the time of assembly. It will thoroughly remove the necessity for you to get a connector for programming. You also won’t have to imprint on the PCB to manufacture it at a lower cost for a much smaller product.
We can do this by inserting the IC into a zero insertion force or ZIF socket. The socket is linked to the correct program in the IC. It also supports the circuitry that can make it work properly. Then, when using the IC in the assembly, we program and package it for later use.
The con to the preprogramming feature is that if there is a production fault or an issue in the change of built, you have to force an upgrade when things are in the middle of production, and then you have zero flexibility. We must reprogram the IC.
If there was any programming header and chosen to eliminate that, then it will become necessary. Without that, there is no way to remove chips that have an incorrect code.
If you decide the method for programming the PCB board, then this is one option that has no flexibility. However, if you are programming bootloaders, then you can freely choose this method. The requirements change very rarely, so you will be fine paying the manufacturer and distributor's setup fee per unit.
（Caption: Programmed IC embedded on PCB with other electronics components ）
3. PCB Programming- Dedicated Headers
It is a reasonably common technique through which you can program a device. It will make sure you can establish a connection easily through the program. It will also allow you as an end-user to have the flexibility to remove and get different software.
One problem with this process is that the connector part may accumulate charge, and we need to assemble it. These connectors are some of the most expensive inventories in the list of the things necessary to construct a circuit board. So, whenever you try to do a finalized run, reducing the connectors' cost should be a priority.
In case this connector is not fixed, you will start to see issues with other connectors getting attached backward. It can give negative incorrectly at the time of programming and testing. A widely used and known example of this is USB connectors. When in production, changing the functionality over USB is usually better as it is repeatable.
(DIY electronic board with a micro-controller, LEDs)
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4.PCB Programming-Manufacturing and Test Jigs
Programming is known to use a jig made of a Pogo Pin. If you are considering doing high volume runs, this is an ideal solution. These contacts are spring-loaded, and they make an excellent electrical connection between the PCBs. We can link the contacts in the PCB to be programmed.
The jig is not only limited to programming. It can also test all the different kinds of utilities on the circuit board. The programming jigs can be used to set up to be able to program the complete panel. It only takes one pass to complete the group. It is excellent for increasing production speed and testing.
The programming jig issue can be that they are pretty challenging to build, which also makes them quite expensive. It means it can be used only for runs above medium volume, balancing out the cost of tooling.
（Abstract PCB programming）
5.PCB Programming- Universal Headers
Universal headers are an option that is somewhere in the middle of the methods we already discussed. The tag connects also creates cables that come with pre-manufactured pogo pins. The specific program is connected to one end of the cable. The other side connects to the contacts of the circuit board. Many other companies have products that are similar to standard pogo adapters.
This kind of programming solves the issue of needing a header that is fit for the work and has the requirement to build a pricey programming jig. It makes it ideal for low to medium volume.
6.PCB Programming-Offline Programming
The best feature of offline PCB programming is that, if you have different chips from packages from separate adapters, it will be compatible with all. This chip can be utilized in combination with the adapter so that you can get higher levels of program burning.
The adapter is to increase the accuracy of the clamp. The different chips and packaging will need separate kinds of adapters. Recently, the outer pack migrates towards the flatter and smaller QFN, BGA, etc. (one good example of this is the widely available EMMC chips). The cost of these adapters cannot be considered very cheap. When you are doing a production test, you can detach the chip if you face any issues, so it is no longer attached to the adapter. Then we can reprogram and use the recommended procedure. The issue with this method is that it will end up costing a lot of power, money, and time.
When programming the PCB board, in the production stage, there can be many emergencies if the CB's temperature is lower than recommended. When removed, it may damage the chip. It will cause higher chances of scrapping.
7.PCB Programming-Online Programming
The online programming method utilizes the usual connector of the chip. It could be any of these, SWD, JTAG, USB, etc. The main interface is mostly fixed. When programming, the number of pins to be connected is small. This communication rate between interfaces is not that high, But usually, we can use this cable without causing high standard consumption.
Since the manufacturing line has been moving towards automation, most manufacturers lean towards test machines for better functionality and automation. The production process, which uses online burning and automatic fixtures, will be excluded at the stage of combustion.
In manual operation，After, the circuit boards are fixed in place; it will burn directly. After this, the PCBA gets directed to the test machine. It makes the complete production process automated, which will elevate the production line's performance and reduce the cost and energy consumption in manufacturing. It is why it has gained traction with the manufacturers in recent times.
(Caption: Online programming during the development phase)
Conclusion
In PCB programming, online burning happens to have a massive significant inefficiency and overhead reduction. This is the most critical indicator in the industry standard and can quantify the manufacturing process's accuracy—the effectiveness of production, price, scale, capital, and quality.
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