2019 Site Electronics Original Development Board is in full swing, this will inevitably involve many developers have many complaints on the actual circuit boards, such as the expected phase difference? How can I make fast design rework in the case of time?
This article introduces 6 simple methods, I hope to be useful to you.
You will not find DFRWK in the list of DFX Design Guide. DFX refers to a variety of design guidelines collected under the "Excellent Design" header. You may have heard more popular guides, such as manufacturability (DFM), assembly design (DFA) or test design (DFT). But how about rework design (DFRWK)?
DFRWK is not part of the guide series, but it should be.
What is the meaning of redo PCB?
For purposes of this article, rework refers to any operation that needs to be completed after completion of the main printed circuit board assembly operation.
Rework tasks are usually divided into two categories:
The problems in the design must be solved, for example:
Your schematic symbol is inconsistent with the PCB package (may result in signal to the wrong pin)
You have selected the wrong resistance value.
You choose the wrong IC
You have forgotten the necessary connection between the two pins (and need to add jumpers)
Design must be changed according to a specific reason, for example:
You need to create new features
You need to change the specification
You need to switch components
In the former case, an error occurs during the design or assembly process, there is a need to change the component or PCB trace for repair. In the latter case, the expected design can work, but it is still no longer required to be the product, so it is necessary to change the component or PCB trace to adjust the design. PCBA rework mainly involves heat and solder, but it may also require mechanical operation, such as cut traces or modify physical components.
When designing a printed circuit board, you may not always consider (if any), your design chooses how to affect future rework operations. However, rework is usually necessary during starting, test or deployment, test or deployment.
PCB rework and PCB repair
You may be studying the above and think that "repair problems" in the PCB is the same as the PCB repair. Differences come from the wrong place. When the circuit board fails because certain reasons, it is usually carried out. There may be an ESD impact or a reverse polar connection. This means that repair is necessary because there is an unexpected fault - may have discard PCB.
On the other hand, rework means that there is a designed error that needs to be corrected.
6 tips for re-processing PCB
Now we have defined the meaning of rework on PCB, let us know how it is complete! You can now take the following six steps to improve the design DFRWK.
Make your PCB bigger
The prototype is rarely as small as the final design, so enlarges the prototype PCB and put it in a ready-made prototype. This will allow you to publish your design faster, waste less time to handle tricky PCB layout issues. To test as part of the system, use the cable to connect larger prototype PCB to the tight position in the system. A larger PCB is more likely to work on the workbench, easier to detect, easier to rework.
Use more components
Although the use of mini BGA elements or 01005 package resistors may look cool and avant-garde, you may not need them - and you don't need them in prototypes. You cannot easily rework part of less than a sugar. For prototypes, unless absolutely necessary, consider using components of not less than 0402, and use the components with exposed leads rather than BGA or QFN packages as much as possible.
Allow more space
When there is more gaps around the part, the rework is easier and more reliable. For BGA, QFN, or other packages without exposed leads, allowing sufficient space around them to be hot for local rework reflux. For high-density connector or pressing connector, the tool using the PCB requires a gap. For mechanical components such as a heat sink, a manual tool such as a pliers is important.
Layout Bundle resistance and jumper options
The goal of the circuit designer is to design everything in the first time. However, you can save a lot of time and trouble by designing strapping resistors so that all sets of pins are high or pulled by simple rework. Or consider adding additional no-filled filter circuits around the power regulator. You can even design the entire secondary circuit, just move the jumper from one connector to another.
Use programmable components
In a possible case, programmable components are used to achieve rework flexibility. Adjusting firmware is usually easier than cutting traces or refolding components. Look for programmable voltage regulators, microcontrollers, or CPLD / FPGAs that may make sense in prototype, even if it is not your final design. Simple, cheap programmable components allow you to redesign your design without your hardware risk.
Install all programming interfaces
Failure to follow this guideline has bite a lot of many designers. Take extra a few cents to install each annoying programming header file. I can hear you all said, "But I can use the JTAG chain program part," or "we built this part with the same code for a long time - we have no chance to change it." Experience if you are Install all programming head files on the prototype, then you will thank me later.
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