When manufacturing a PCB board, especially a multilayer PCB used in industrial, aerospace, medical, UAV, and defense electronics, one important process step cannot be ignored: surface treatment. Many engineers focus on Gerber files, layout drawing, netlist accuracy, schematic diagram integrity, or PCB prototype fabrication, but overlook the importance of surface finishing. In reality, surface treatment plays a decisive role in the durability, solderability, and long-term performance of a printed circuit board.
Quando si produce una scheda PCB, in particolare un PCB multistrato utilizzato in ambito industriale, aerospaziale, medicale, UAV e difesa, un passaggio importante del processo non può essere ignorato: il trattamento superficiale. Molti ingegneri si concentrano sui file Gerber, sul disegno del layout, sulla precisione della netlist, sull’integrità dello schema elettrico o sulla fabbricazione di prototipi di PCB, ma trascurano l’importanza della finitura superficiale. In realtà, il trattamento superficiale gioca un ruolo decisivo per la durata, la saldabilità e le prestazioni a lungo termine di un circuito stampato. Una superficie in rame grezzo su una scheda PCB si ossida rapidamente se esposta a ossigeno, umidità o contaminanti chimici. Il rame ossidato impedisce una corretta saldatura, porta a una connettività elettrica instabile e riduce significativamente l’affidabilità del montaggio dei componenti. Pertanto, che il PCB sia a due strati o multistrato ad alta densità, una finitura superficiale adeguata garantisce che le piazzole di rame rimangano stabili, conduttive e pronte per la saldatura durante lo stoccaggio, l’assemblaggio e l’utilizzo a lungo termine.
A raw copper surface on a PCB board oxidizes quickly when exposed to oxygen, moisture, or chemical contaminants. Oxidized copper prevents proper solder bonding, leads to unstable electrical connectivity, and significantly reduces component mounting reliability. Therefore, whether the PCB is two-layer or high-density multilayer printed circuit board, a proper surface finish ensures the copper pads remain stable, conductive, and solder-ready throughout storage, assembly, and long-term usage.
There are several popular surface treatment methods, each selected based on application scenario, cost, and expected reliability. HASL (Hot Air Solder Leveling) is one of the earliest and most widely used finishes. It creates a uniform solder layer on exposed copper areas and is suitable for general electronics. However, for high-frequency and fine-pitch designs found in advanced electronic circuit board systems, HASL may not meet precision tolerance requirements.
Bei der Herstellung von Leiterplatten, insbesondere von mehrlagigen Leiterplatten für die Bereiche Industrie, Luft- und Raumfahrt, Medizintechnik, UAV und Verteidigungselektronik, ist ein wichtiger Prozessschritt unerlässlich: die Oberflächenbehandlung. Viele Ingenieure konzentrieren sich auf Gerber-Dateien, Layoutzeichnungen, Netzlistengenauigkeit, Schaltplanintegrität oder die Prototypenfertigung, vernachlässigen aber die Bedeutung der Oberflächenveredelung. Dabei spielt die Oberflächenbehandlung eine entscheidende Rolle für die Haltbarkeit, Lötbarkeit und Langzeitleistung einer Leiterplatte. Eine unbehandelte Kupferoberfläche oxidiert schnell bei Kontakt mit Sauerstoff, Feuchtigkeit oder chemischen Verunreinigungen. Oxidiertes Kupfer verhindert eine ordnungsgemäße Lötverbindung, führt zu instabilen elektrischen Verbindungen und reduziert die Zuverlässigkeit der Bauteilmontage erheblich. Daher gewährleistet eine korrekte Oberflächenveredelung – unabhängig davon, ob es sich um eine zweilagige oder eine hochdichte mehrlagige Leiterplatte handelt –, dass die Kupferpads während Lagerung, Montage und Langzeitnutzung stabil, leitfähig und lötbereit bleiben.
Another advanced finishing method is ENIG (Electroless Nickel Immersion Gold). This surface treatment provides excellent flatness, corrosion resistance, and strong solder adhesion. ENIG is widely used in multilayer PCB fabrication, especially for RF modules, miniaturized drone control boards, counter-UAV systems, and any sensitive signal-integrity-dependent circuits. Its gold surface ensures superior conductivity and oxidation resistance, which is crucial in harsh outdoor or military environments.
On the printed circuit board, copper is used to interconnect the components on the substrate. Although it is a good conductor material for forming the pattern of the conductive path of the printed circuit board, it will also be exposed to the air for a long time. It is easy to lose luster due to oxidation, and lose weldability due to corrosion, that is the main reason Why we need to have Surface Treatment over PCB Board;
Why we need to have Surface Treatment over PCB Board
Therefore, various technologies must be used to protect copper traces, vias, and plated through holes. These technologies include organic paint, oxide film, and electroplating.
Organic paint is very simple to apply, but it is not suitable for long-term use due to changes in its concentration, composition and curing cycle. It even leads to unpredictable deviations in solderability. Oxide film can protect the circuit from corrosion, but it cannot maintain solderability.
Electroplating or metal coating processes are standard operations to ensure solderability and protect circuits from corrosion, and play an important role in the manufacture of single-sided, double-sided, and multilayer printed circuit boards. In particular, plating a layer of solderable metal on the printed wire board has become a standard operation to provide a solderable protective layer for the copper printed tracks.
Lors de la fabrication d’une carte de circuit imprimé (PCB), notamment d’une PCB multicouche utilisée dans les secteurs industriel, aérospatial, médical, des drones et de la défense, une étape cruciale est à ne pas négliger : le traitement de surface. Nombre d’ingénieurs se concentrent sur les fichiers Gerber, le schéma d’implantation, la précision de la netlist, l’intégrité du schéma électrique ou la fabrication de prototypes, mais oublient l’importance de la finition de surface. Or, ce traitement joue un rôle déterminant dans la durabilité, la soudabilité et les performances à long terme d’une carte de circuit imprimé. Une surface de cuivre brute s’oxyde rapidement au contact de l’oxygène, de l’humidité ou de contaminants chimiques. L’oxydation du cuivre empêche une bonne soudure, engendre une connectivité électrique instable et réduit considérablement la fiabilité du montage des composants. Par conséquent, qu’il s’agisse d’une carte bicouche ou d’une PCB multicouche haute densité, une finition de surface appropriée garantit la stabilité, la conductivité et la soudabilité des pastilles de cuivre pendant le stockage, l’assemblage et l’utilisation à long terme.
In addition, some applications require specialized finishes such as OSP (Organic Solderability Preservative), Immersion Tin, Immersion Silver, or ENEPIG, depending on bonding technology, storage life, or mechanical stress demands. For example, ENEPIG is widely applied to boards requiring wire bonding or hybrid interconnect.
Surface treatment also affects the reliability of reverse engineering, remanufacture, or redesign processes. When engineers attempt to restore, recover, clone, or reproduce PCB boards, especially old prototypes, degraded or contaminated pad surfaces often complicate measurement, soldering, or electrical continuity checks. In such cases, a fresh surface treatment helps bring the restored PCB to a functional manufacturing condition.
In summary, surface finishing is not just a cosmetic step—it protects copper traces from oxidation, ensures stable solderability, improves electrical performance, and extends the functional lifespan of the PCB. As circuit density increases and multilayer boards become standard in high-performance electronics, choosing the right surface treatment becomes essential rather than optional. For modern applications, especially mission-critical systems, a well-engineered surface finish is the foundation of reliable PCB functionality.
Al fabricar una placa PCB, especialmente una PCB multicapa utilizada en electrónica industrial, aeroespacial, médica, de vehículos aéreos no tripulados (UAV) y de defensa, hay un paso importante que no se puede ignorar: el tratamiento de la superficie. Muchos ingenieros se centran en los archivos Gerber, el diseño, la precisión de la lista de conexiones, la integridad de los diagramas esquemáticos o la fabricación de prototipos de PCB, pero pasan por alto la importancia del acabado superficial. En realidad, el tratamiento de la superficie desempeña un papel decisivo en la durabilidad, la soldabilidad y el rendimiento a largo plazo de una placa de circuito impreso. Una superficie de cobre sin tratar en una placa PCB se oxida rápidamente al exponerse al oxígeno, la humedad o los contaminantes químicos. El cobre oxidado impide una correcta unión de la soldadura, provoca una conectividad eléctrica inestable y reduce significativamente la fiabilidad del montaje de los componentes. Por lo tanto, ya sea una PCB de dos capas o multicapa de alta densidad, un acabado superficial adecuado garantiza que las almohadillas de cobre se mantengan estables, conductoras y listas para soldar durante el almacenamiento, el montaje y el uso a largo plazo.
