Research On Tinning Process Of Surface-mount Fine-pitch Devices

At present,tinning and welding,as two important steps,play an important role in the process of installation operation.The quality of tinning and welding directly affects the quality of electrical installation.At present,the reliability of electronic and electrical products is highly demanded in the current production environment of aerospace.In order to ensure the welding quality and improve the solderability of the lead,the lead of components usually needs to be tinned before assembly.Gold-plated devices also need to be tinned to achieve the purpose of gold removal.Surface mounted fine pitch devices are still tinned by manual clamping because of the short pin and small spacing of pins.In the process of manual tinning operation,there is a short circuit at the front end of the pin,and there is a problem of pin distortion when the electric soldering iron is used.In addition,it may cause thermal damage to devices and poor rate of finished products.In order to satisfy the quality and reliability of tin enameling and welding,this paper studies the technology of surface-mounted fine-pitch devices in tin enameling.In this paper,the automatic tinning equipment is used to realize the automation of tinning for the fine gauge device,and the position and time of tinning can be controlled.On this basis,the device suction tooling was designed to avoid the jitter of hand-held device enamel and minimize the damage caused by enamel to components.Inert gas protection is adopted to reduce the surface tension of the adjacent pins of the surface-mounted fine-pitch devices,and cooperating with the technological modification of the tin pot to prevent the oxidation of the tin,thus reducing the tin-enameled short-circuit defects of the surface-mounted fine-pitch devices.In the process of automatic tin-enameling,three factors are tested and appropriate process parameters are obtained,The paper analyzed and validated the fine pitch devices after the tin enameling process,checked its reliability,and finally verified the feasibility and reliability of the process.Studies have shown that the problem of short circuit of tinning with fine pitch devices can be greatly reduced by using automatic tinning equipment through nitrogen protection,reliable non-destructive absorption technology of components based on compressed air conversion vacuum and flowing tin pot.Through experiments,it is concluded that under the condition of nitrogen concentration is close to 100%,the pins of components are preheated before tin enameling(80 C),the devices withdraw tin evenly from the tin pot at one corner and accelerate from the other corner when they leave the tin pot,the device has no short circuit and the reliability is high,which meets the technological requirements of surface-mounted fine-pitch device tin enameling in aerospace products.In practical production,the uncontrollability of manual participation can be avoided,which not only guarantees the quality,but also reduces the process cost and improves the efficiency.It changes the limitation of manual tin enameling and it can replace the traditional manual tinning.