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.

Hard gold

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.