Reverse engineering of printed circuit boards (sometimes called “cloning”, or PCB RE) is the process of generating fabrication and design data for an existing circuit board, either closely or exactly replicating its functionality. Obtaining circuit board design data is not by necessity malicious or aimed at intellectual property theft. The data generated in the reverse engineering process can be used for troubleshooting, repair, redesign and re-manufacturing, or even testing the security of a device to be used in a restricted environment.
Uses
Legacy product support Legacy systems need maintenance and replacement parts to operate past their intended life cycle. Demand for parts that are no longer being manufactured can lead to material shortages of parts, called DMS/DMSMS. There is much demand that entire government divisions have been created to regulate and plan the obsolescence of those systems and parts. Areas commonly affected by technical obsolescence include power station controls, ATC and aviation controls, medical imaging systems, and many aspects of military technology. There are many legacy systems developed in the 70s, 80s or 90s whose original manufacturer is no longer in business or no longer has the original design data, but whose original equipment is still in use. In many cases exact form, fit and function is required, either that so parts can “handshake” properly with the existing framework, or to avoid requirements of time-consuming and costly testing. For industries with highly regulated electronics, (like military or aerospace) this approach can vastly reduce the time required to fabricate replacement parts for system repairs, since the new part's specifications match the original design exactly and therefore do not need to undergo the same level of rigorous re-certification and testing that would be required of a newly designed or revised circuit board. For example, a power company in Florida was forced to shut down due to the failure of a single, inexpensive PCB, which had no replacement parts and no data available to print them. The failure occurred during peak usage hours, and a power outage at that time can cost a power company thousands of dollars per hour. An engineering firm successfully reverse engineered the PCB to generate an exact copy of the PCB using the destructive imaging and milling process, and the power station was subsequently able to resume normal operation.
Benchmarking The process can be used to provide important benchmarking information about newly acquired products, prototype PCBs or any circuit board the company does not own. For example, reverse engineering a circuit assembly reveals whether or not the fabricator has exactly matched the design specifications of the board. The process can be used to inspect for counterfeit or malicious circuits embedded in a PCB, or, if a new product has been purchased by a company, to create schematics or other documentation that may not have been included with the product.
Use with additive manufacturing Data from the reverse engineering process can be used to immediately repair or reprint a circuit board using additive manufacturing techniques on multi-headed 3-D printers. In situations where resources are limited like on a ship, submarine, space, or forward deployment, the reverse engineering process can enable a crew to maintain electronics equipment without being required to bring along spare parts. In an ideal scenario, the crew would have access to the design data to use with the 3D printer, but in the event that crew did not have the proper data for the PCBs, they would need to reverse engineer the artifact on hand to create more.
Malicious intent Data from reverse engineering can be taken with good intentions but mitigating intellectual property theft and maintaining privacy is increasingly important. Obfuscating PCBs, or hiding the intent of processing is one way to help deter theft. Another is using physical unclonable functions (PUFs) as a digital fingerprint on your PCB that is impossible to recreate.
Methods
Types
Destructive RE Destructive reverse engineering (DRE) is a process where all layers of the board are imaged and subsequently removed by various milling techniques or tools. While it is possible to use nearly any camera or image source for this method, purpose-built RE systems utilize calibrated image sources that allow for extremely accurate reproduction of the design data for the board. This allows an engineer to match the exact form, fit and function of the original PCB. The drawback to this method is that it destroys the PCB. If the data comes from the last remaining circuit card in existence, it cannot be compared to a sample since little or no circuit board remains at the end of the destructive process. Also, care must be taken during the milling process to avoid damaging the copper. If areas of copper are removed before they are imaged, this represents a permanent loss of data which can only be rectified by existing documentation of the PCB, or by reverse engineering a second, identical board.
Non-destructive RE
There is a growing desire and need for non-destructive reverse engineering technology (NDRE), especially in scenarios like the one mentioned above where there is only a single PCB that can be used. Non-destructive PCB RE (NDRE) mean that the circuit board itself is not destroyed in the process; however, most non-destructive techniques require removing components from the surface of the board. The primary difference between DRE and NDRE methods are in the way that images for the board are captured before new data is generated - in some cases optical images of the top and bottom of the board are captured, then merged with X-ray images of the boards internal layers. Once all images of all of the layers of the board have been captured the process of generating digital manufacturing data is similar to the destructive process.
X-ray computed tomography
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