FPC liner with small solder joints, this welding process is now known as precision welding, the traditional welding method is generally manual welding or automatic soldering machine, but the speed, process and quality of both are very different from the laser welding process. The quality of welding is related to the quality of the product. Next, let's compare the difference between manual and laser welding.
Manual Soldering
1. Before pasting and aligning the FPC and PCB board, the smoothness and oxidation of the PCB pads should be checked. Peel off the FPC double-sided tape and paste it on top of the PCB gold finger board. Please note that after pasting, the PCB pads must leak about 1.0 mm of wire pins.
2. Solder: The reference time is 1-2 seconds and must be soldered according to the white marking line on top of the FPC. (Solder reference time 1-2S) The main control of the time and location of the solder feed and drag solder:.
The four main control points of the solder feed and drag welding:
Time: generally recommended drag welding time according to the length of the iron head 3S calculation, about 4 ~ 10S.
Temperature: two hundred and ninety degrees to three hundred and ten degrees.
Feed tin position: the best position to feed tin in the tip of the soldering iron below the position, the position is biased towards the pad.
Force: soldering iron tip and the workpiece contact strength: the tip of the soldering iron and the workpiece contact to apply a little pressure, the principle is not to cause damage to the FPC gold finger.
3. Self-check after welding: 45 degree angle observation. After welding, you must spend 1-2 seconds self-inspection to see if there are defects such as false welding, continuous welding or deviation.
Laser soldering process:
1、The brazing ball automatically rolls at the nozzle and the nozzle catches the unmelted brazing ball.
2, the nozzle begins to fill with nitrogen.
3、When the nitrogen pressure reaches the pre-set value. The laser irradiation starts and the melting process of the brazing ball begins.
4、The brazing ball melts and is ejected under the pressure of nitrogen.
5、The brazing ball touches the pad and forms a bump, the pad does not need to be preheated.
Advantages of using laser solder ball spray welder:
(1) High energy density, low heat input, small thermal deformation, narrow melting zone and heat affected zone, and large penetration depth.
(2) Due to the fast cooling speed, the weld is finely organized and the joint performance is good.
(3) Since it is non-contact welding, no electrode is used, so it saves man-hours.
(4) The welding speed is fast and can be completed within 0.2 S.
After looking at manual welding and laser welding, I believe we all know that the welding method has more advantages. Laser brazing ball welding is suitable for high precision welding with an accuracy of ±10um and a minimum gap of 100um. soldering balls are available in a wide range with a minimum diameter of 70um. applied to tin, gold, silver and other metal surfaces with a yield of over 99%, laser soldering machines are suitable for uninterrupted precision welding processes.
