PCB Technical - Four common problems in circuit board factory production

In the process of circuit board design and circuit board production, engineers not only need to prevent accidents in the PCB board manufacturing process, but also need to avoid design errors. The editor of ipcb Circuit Board Factory will understand with you that the four common PCB problems of circuit board manufacturers are summarized and analyzed, hoping to bring some help to everyone's design and production work.

Problem 1: Circuit board short circuit: For this kind of problem, it is one of the common faults that will directly cause the circuit board to not work. There are many reasons for this kind of board problem. The following editor will lead you to understand and analyze one by one. The biggest cause of PCB short circuit is improper solder pad design. At this time, the round solder pad can be changed to an oval shape to increase the distance between points to prevent short circuits. Inappropriate design of the direction of the PCB proofing parts will also cause the board to short-circuit and fail to work. For example, if the pin of the SOIC is parallel to the tin wave, it is easy to cause a short-circuit accident. At this time, the direction of the part can be appropriately modified to make it perpendicular to the tin wave. There is also a possibility that the short circuit failure of the PCB will be caused, that is, the automatic plug-in bending foot. As the IPC stipulates that the length of the pin is less than 2mm and there is concern that the parts will fall when the angle of the bent leg is too large, it is easy to cause a short circuit, and the solder joint must be more than 2mm away from the circuit.

Problem 2: PCB solder joints become golden yellow: Generally, the solder on PCB circuit boards is silver-gray, but occasionally there are golden solder joints. The main reason for this problem is that the temperature is too high. At this time, you only need to lower the temperature of the tin furnace.

Problem 3: Dark-colored and granular contacts appear on the circuit board: Dark-colored or small-grained contacts appear on the PCB. Most of the problems are caused by the contamination of the solder and the excessive oxides mixed in the molten tin, which form the solder joint structure. crisp. Be careful not to confuse it with the dark color caused by the use of solder with low tin content. Another reason for this problem is that the composition of the solder used in the manufacturing process has changed, and the impurity content is too high. It is necessary to add pure tin or replace the solder. The stained glass causes physical changes in the fiber build-up, such as separation between layers. But this situation is not due to poor solder joints. The reason is that the substrate is heated too high, so it is necessary to reduce the preheating and soldering temperature or increase the speed of the substrate.

Problem 4: Loose or misplaced PCB components: During the reflow soldering process, small parts may float on the molten solder and eventually leave the target solder joint. Possible reasons for the displacement or tilt include the vibration or bouncing of the components on the soldered PCB board due to insufficient circuit board support, reflow oven settings, solder paste problems, human error, etc.