Circuit board spray tin  function and technics procedure introduction

300 Published by FASTPCBA 8月 22,2019

Circuit board spray tin  function and technics procedure introduction

The so-called spray tin is to soak the pcb board into the molten tin-lead. When the surface of the board is covered with enough tin-lead, the excess tin-lead is scraped off by hot air pressurization. After the tin-lead is cooled, the soldered area of the board is coated with a suitable thickness of tin-lead, which is a rough procedure for the spray tin procedure. PCB surface treatment technology, the most widely used is the spray tin technics, also known as hot-air leveling technology, which is to spray a layer of tin on the pad to enhance the conductivity and solderability of the PCB pad.

Circuit board spray tin  function and technics procedure introduction

Spray tin (SMOBC & HAL) is one of the most common surface coating forms for pcb circuit board surface treatment. It is widely used in the production of circuit. The quality of spray tin directly affects the quality of soldering in subsequent customers and solderability. Therefore, the quality of spray tin has become a focus of quality control for circuit board manufacturers about general double-panel, tin-spraying and OSP technics are the most widely used, while rosin technics is widely used on single-sided PCBs, and gold plating is applied to circuit board which bonding ic. Immersion gold is applied more on the card board.


The PCB spray tin technics process is mainly: placing the board (gold-plated plug protection tape) – hot air leveling pre-treatment – hot air leveling – hot air leveling after cleaning – inspection.


Although the overall technics is simple, there are still many technics conditions to master if there is a hot air leveling out of a good qualified pcb printed circuit board, such as: solder temperature, air knife air temperature, air knife pressure, dip soldering time, lifting speed. These conditions have setting values, but they must be changed according to the external conditions of the printed circuit board and the requirements of the processing doc, such as: board thickness,board length. Different single-sided, double-sided, multi-layer boards. The conditions they used are different. Only when they are familiar with various technics parameters, according to the different types of printed circuit boards, different requirements, patience, meticulous and reasonable adjustment of the machine, can the hot air level out the qualified printed circuit board.

The main function of PCB spray tin:

Preventing oxidation of bare copper surface; copper is easily oxidized in the air, causing the PCB pad to be non-conducting or reducing the soldering performance. By applying tin on the copper surface, the  copper surface can be isolated from the gas effectively to maintain the PCB conductivity and solderability.


(2) Maintaining solderability; other surface treatment methods include: hot melt, organic protective film OSP, chemical tin, chemical silver, chemical nickel gold, electroplated nickel gold, etc.; PCB board technics characteristics: The tin-plating board consists of two layers of copper and tin metal which can adapt to the poor environment and the soldering performance is better in high temperature and corrosive environment.


This kind of board is widely used in industrial control equipment communication products and military equipment products. The advantages of tin-plated PCB: in the usual PCB surface treatment, the tin-spraying technics is called the best solderability because there is tin on the pad. When soldering tin, it is easier to use with gold plate or rosin and OSP technics. This is very easy for us to solder manually, and it is very easy to solder.

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