2 Notes on PCB Reverse Engineering

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2 Notes on PCB Reverse Engineering

Computerized tomography

A computerized tomography is a powerful tool for reverse engineering PCBs. This technique uses x-rays to take images of the inside of a circuit board. The resulting image can be used to reconstruct the board’s structure. Computerized tomography has several limitations, however. Its field of view is small, which makes it less effective for PCBs with large areas of copper foil.

Computerized tomography is not a good choice for all reverse engineering projects. CT scans can result in inaccurate results. It’s best to use a non-destructive method, which gives you more margin of error. CT scans are commonly used in this process, but you can also use X-ray tomography to capture the inside of a substance. It can also extract geometrical information, which can be extremely helpful for re-engineering circuit boards without destroying the device.

The main drawbacks of CT are the fact that x-rays can distort the image and cause a lot of artifacts. Additionally, the powerful X-rays can damage IC chips. In addition, the board needs to be depopulated before the process can begin.

In contrast, reverse engineering PCBs use a deconstructing method to understand complex things. This method is not limited to hardware engineering; it’s used in software development and human DNA mapping. This process starts with the PCB and works backward from it to the schematics to analyze how it works.

Another advantage of PCB reverse engineering is the ability to produce high-resolution optical images of a board with up to six layers in a few hours. It also has a low cost. The results can be sent directly to a PCB manufacturer for replica PCBs.

Computerized tomography can also be used to analyze multilayer PCBs. The results can also be used to generate a bill of materials. It is recommended to supply a sample PCB when PCB reverse engineering is needed. The sample board should be at least 10 mm in width.

Another benefit of using computerized tomography is that it allows the user to visualize individual components. In addition, it can also determine GD&T controls. A PC-DMIS can export features to polylines and step files. This allows the user to visualize the connections made on the printed circuit board.

Røntgen

X-ray for PCB reverse engineering is a relatively new technique for identifying components on a printed circuit board. Traditional methods rely on de-layering the PCB, which is a time-consuming, error-prone, and damaging process. X-ray for PCB reverse engineering, on the other hand, requires no physical damage to the PCB and takes much less time to evaluate. This method also allows the researcher to extract data from the circuit board.

X-ray for PCB reverse engineering is often used for reverse engineering, but the cost of purchasing such an inspection machine can be prohibitive for many people. One hardware hacker, John McMaster, decided to build his own X-ray to use in his own lab to save money.

Another important consideration is the resolution of the X-ray. Low resolution survey scans can reveal the main components of a board, but submicron resolution is needed to see traces and interconnects. Current micro-CT scanners and XRMs do not have the resolution necessary for this. Moreover, imaging a large PCB at coarse resolution can take hours. Furthermore, the X-ray beam can be harden and create streaks and bands.

PCB reverse engineering is a process of analyzing existing electronic products and recreating them with superior features and lower cost. During the process, documents are generated and sent to a PCB manufacturer for fabrication of a replica PCB. This method can also be used to reduce the time required for repairs and new circuit boards. In addition, it can reveal whether or not a given fabricator is a good match.

The process begins by cleaning the surface of a PCB. Afterward, the X-ray can reveal hidden information within the part. In addition, it can be used to solve quality and failure problems. It can also be used to create computer-aided design models of internal surfaces and trace connections.

Things to Know Before Ordering a PCB Project

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Things to Know Before Ordering a PCB Project

If you are going to order a PCB project, there are a few things that you should be aware of. For instance, you must double check your traces before ordering. In addition, you need to make sure that your BOM and drill file match. Moreover, you must choose the right material.

Double checking traces

When ordering PCBs from a PCB manufacturer, it is crucial to double-check the traces and spacing on your board. The thickness and width of the traces on your project will determine the amount of current that can flow through the circuit. You can use an online trace width calculator to find the ideal trace width. This will reduce the chances of connections breaking.

Checking your BOM

The first step in ordering PCB components is checking your BOM. It will help you avoid missing or incorrect component numbers. Using the BOM is also beneficial when it comes to sourcing parts. The description of the component will help the buyer and assembly house find a suitable replacement part. This will also help them confirm that the parts have the right MPN.

It is important to check your BOM before sending the PCB project to a manufacturer. This is because even a small mistake can cause problems during the PCB assembly process. You should also keep track of any changes made to the BOM and label them clearly. The most up-to-date version of the BOM is the one that you should use.

Once you have your BOM, you need to find out the cost of the component you’re ordering. It is important to know exactly what you’re going to be paying. The price of your components should match the BOM of your PCB project. If not, you may have to replace the components or even change the design.

Checking your drill file

You can easily check your drill file before ordering your PCB project from a PCB manufacturing company. However, there are some important things you must remember before placing an order. The first step is to make sure that the file is in the correct format. You can use a gerber file viewer to double check your file.

A drill file is a secondary file that explains where holes should be drilled on the PCB. This file must be sent along with the Gerber files. If your Drill file does not specify the locations or sizes of holes, your PCB order will fail the audit.

The drill file should also contain a tool list. It lists which tools are needed for each component hole. The tool list should be either embedded in the drill file or be sent as a separate text file. Failure to provide this tool list on the fabrication drawing will eliminate automated verifications and result in more errors when it comes to data entry.

Choosing the right materials

Choosing the right materials for your PCB project is essential. The physical properties of PCB materials can significantly affect the performance of the board. For example, a lower dielectric constant will mean thinner dielectrics and lower board thickness, while a higher dielectric constant will lead to higher losses. This information will help you narrow down your selection of PCB materials and find those that deliver the required performance.

Next, you should determine the number of routing layers on your PCB. For a simple PCB design, there may be only one or two layers, while a moderately complex design may need four to six layers. More complicated designs may require eight layers or more. The number of layers will directly affect the cost of your PCB project.

How to Know the Surface Finish From PCB Color

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How to Know the Surface Finish From PCB Color

If you’re wondering how to know the surface finish of a PCB, you’re not alone. The color of a PCB can reveal its surface finish. You may also see a color designation called ENIG or Hard gold, Silver, or Light red. Regardless of what you see, you’ll want to make sure the PCB is plated to protect the surface.

ENIG

ENIG surface finish is one of the most popular finishes for PCBs. It is made by combining gold and nickel. The gold helps protect the nickel layer from oxidation, and nickel acts as a diffusion barrier. The gold layer has a low contact resistance and is usually a thin layer. The thickness of the gold layer should be consistent with the requirements of the circuit board. This surface finish helps extend the life of the circuit board. It also has excellent electrical performance and enhances electrical conduction between the PCB’s components.

ENIG surface finish has a higher cost but a high success rate. It is resistant to multiple thermal cycles and displays good solderability and wire bonding. It is composed of two metallic layers: a layer of nickel protects the base copper layer from corrosion, and a layer of gold acts as an anti-corrosion layer for the nickel. ENIG is suitable for devices that require high levels of solderability and tight tolerances. ENIG is also lead-free.

Hårdt guld

Hard gold is a costly PCB surface finish. It is a high-quality, durable finish that is often reserved for components that see a high level of wear and tear. Hard gold is usually applied to edge connectors. Its main use is to provide a durable surface for components that undergo frequent actuation, such as battery contacts or keyboard contacts.

Hard electrolytic gold is a gold plated layer over a nickel barrier coat. It is the most durable of the two and is typically applied to areas that are susceptible to wear and tear. However, this surface finish is very expensive and has a low solderability factor.

Silver

Depending on the PCB’s composition, it can be produced with different colors and finishes. The three most common colors for PCB surfaces are silver, gold, and light red. PCBs with a gold surface finish are usually the most expensive, while those with a silver finish are cheaper. The circuit on the PCB is primarily made of pure copper. Because copper oxidizes easily when exposed to air, it is very important to protect the outer layer of the PCB with a protective coating.

Silver surface finishes can be applied using two different techniques. The first technique is immersion, in which the board is immersed in a solution containing gold ions. The gold ions on the board react with the nickel and form a film that covers the surface. The thickness of the gold layer must be controlled so that the copper and nickel can remain solderable, and the copper is protected from oxygen molecules.

Lys rød

Overfladen på et printkort kan være blank, ikke-blank eller lys rød. En ikke-blank finish har tendens til at se mere porøs ud, og en blank finish har tendens til at være reflekterende og hård skal-lignende. Grøn er den mest populære PCB-farve, og det er også en af de billigste. Det er vigtigt at rengøre PCB'er, før man bruger dem, for at undgå oxidering.

Selvom loddemaskens farve ikke direkte afspejler printkortets ydeevne, bruger nogle producenter den som et designværktøj. Farven er ideel til PCB'er, der kræver strålende synlighed og skarpe kontraster. Røde PCB'er er også attraktive, når de kombineres med silketryk.

Elektroløst palladium

Ved at bruge den elektroløse palladiumoverfladebehandling på dine printkort undgår du, at der dannes sorte puder på kortet, og det har mange fordele, herunder fremragende loddeevne og binding af aluminiums- og sølvtråde. Denne type finish har også en ekstremt lang holdbarhed. Men den er også dyrere end andre overfladebehandlinger og kræver længere leveringstid.

ENEPIG's PCB-overfladebehandlingsproces omfatter flere trin, som hver især kræver omhyggelig overvågning. I det første trin aktiveres kobber, efterfulgt af deponering af kemisk nikkel og palladium. Derefter gennemgår printkortet en rengøringsprocedure for at fjerne oxidationsrester og støv fra overfladen.

Blyfri HASL

Hvis du er på udkig efter et nyt printkort, spekulerer du måske på, hvordan du kan skelne blyfri HASL-overfladefinish fra blybaserede printkort. Selvom HASL har et attraktivt udseende, er det ikke ideelt til overflademonterede komponenter. Denne type finish er ikke flad, og større komponenter, som f.eks. modstande, kan ikke justeres korrekt. Blyfrit HASL er derimod fladt og bruger ikke blybaseret loddemetal. I stedet bruges en kobberbaseret loddemetal, der er RoHS-kompatibel.

HASL giver loddeevne af høj kvalitet, og det kan modstå flere termiske cyklusser. Det var engang industristandard, men indførelsen af RoHS-standarder gjorde, at det ikke længere var i overensstemmelse med reglerne. I dag er blyfri HASL mere acceptabel med hensyn til miljøpåvirkning og sikkerhed, og det er et mere effektivt valg til elektroniske komponenter. Det er også mere i overensstemmelse med RoHS-direktivet.

Tips til viden om semifleksible FR4 printkort

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Tips til viden om semifleksible FR4 printkort

FR4 er et flammehæmmende materiale

Printkort fremstillet af FR4 er ekstremt holdbare. Men prisen på disse printkort er højere end på dem, der er lavet af andre materialer. Derudover har disse printplader tendens til let at delaminere, og de udsender en dårlig lugt, når de loddes. Det gør dem uegnede til high-end forbrugerelektronik.

FR4 er et kompositmateriale, der har fremragende mekaniske, elektriske og flammehæmmende egenskaber. Det er et gult til lysegrønt materiale, der tåler høje temperaturer. Det er lavet af et glasfiberlag, der giver materialet dets strukturelle stabilitet. Materialet har også et lag af epoxyharpiks, der giver det dets brandhæmmende egenskaber.

FR4-printkort kan produceres med varierende tykkelse. Materialets tykkelse påvirker printkortets vægt og komponenternes kompatibilitet. Et tyndt FR4-materiale kan være med til at gøre en printplade lettere, hvilket gør den mere attraktiv for forbrugerne. Dette materiale er også let at sende og har fremragende temperaturbestandighed. Det anbefales dog ikke til brug i miljøer med høje temperaturer, f.eks. i rumfart.

Det har fremragende termiske, mekaniske og elektriske egenskaber.

FR-4 er et almindeligt printkortsubstrat fremstillet af glasvæv imprægneret med epoxy- eller hybridharpiks. Det bruges i vid udstrækning i computere og servere og er kendt for sine fremragende termiske, mekaniske og elektriske egenskaber. Det kan modstå høje temperaturer, hvilket gør det til et ideelt valg til følsom elektronik.

FR4 semi-flex PCB'er giver dog nogle udfordringer, når det gælder dybdekontrollerende fræsning. For at opnå gode resultater med denne type materiale, skal pladens resterende tykkelse være ensartet. Mængden af resin og prepreg, der bruges, skal også overvejes. Fræsetolerancen skal indstilles korrekt.

Ud over de fremragende termiske, mekaniske og elektriske egenskaber er FR4 let og billigt. At det er tyndt, er en stor fordel i forhold til FR1-printplader. Det skal dog bemærkes, at dette materiale har en lavere glasovergangstemperatur end FR1 eller XPC. FR4-printkort er lavet af otte lag glasfibermateriale. Disse printkort kan modstå temperaturer mellem 120 grader C og 130 grader C.

Det har et højt signaltab sammenlignet med et højfrekvent laminat.

Selvom FR4's lave pris og relative mekaniske og elektriske stabilitet gør det til et attraktivt valg til mange elektroniske applikationer, er det ikke egnet til alle applikationer. I tilfælde, hvor der kræves højfrekvente signaler, er et højfrekvent laminat et bedre valg.

Laminatmaterialets dielektriske konstant spiller en afgørende rolle i valget af det bedste printkort. Jo højere den dielektriske konstant er, jo mindre signaltab vil printkortet opleve. Denne dielektriske konstant er et mål for pladens evne til at lagre elektrisk energi.

Når man sammenligner signaltabet på et printkort med et højfrekvent laminat, kan man se, at førstnævnte har en højere dielektrisk konstant. Med andre ord har Semi-Flex FR4-materialet en højere dielektrisk konstant end sidstnævnte. En høj dielektrisk konstant er ønskværdig til højhastighedsapplikationer, fordi den forhindrer signaltab.

FR-4 var ikke det første PCB-materiale, der blev brugt til elektronik. Forud var gået FR-2-pladen, som var lavet af presset phenol-bomuldspapir. Dette materiale fungerede som en bro mellem diskret kablede håndloddede kredsløb og FR-4. I nogle Magnavox-reklamer blev der reklameret med, at fjernsynene var "håndloddede". FR-2-kort var ofte ensidige, men designere kunne løse problemet ved at bruge jumpere på oversiden og nul-ohm-modstande.

Det kan fremstilles til en lav pris

Semi-flex PCB'er er fleksible og ideelle til applikationer, hvor pladsen er en faktor. Disse printkort er dyrere end konventionelle FR4-kort, men den fleksibilitet, de giver, gør dem ideelle til mange medicinske anvendelser. Den fleksibilitet, de giver, er også bedre egnet til at håndtere dynamisk stress som følge af bøjede printkort.

Semifleksible PCB'er er lavet af materialer, der typisk fremstilles i ruller. Disse materialer skæres derefter til i henhold til produktets endelige størrelse. For eksempel skæres en rulle kobberfolie til den ønskede form, som derefter kræver mekanisk boring for at lave de gennemgående huller. Der bruges forskellige huldiametre, som varierer alt efter kundens behov.

Materialets bøjningsegenskaber kan dog give problemer. For eksempel er FR4 ikke egnet til bøjning ved meget høje temperaturer, da det har tendens til at vride sig. For at forhindre sådanne problemer er det nødvendigt at sikre, at materialerne er lavet af et fleksibelt materiale, før de ætses eller støbes.