for the SMT processing plant for the processing of tin beads appear in the process is necessary to solve, a good SMT processing plant is to do their best to exclude all processing defects.
The first step is to know the cause of the problem, SMT chip processing plant to analyze the causes of tin beads appear.
Tin beads (solder beading) is the term used to distinguish a kind of tin ball that is unique to sheet components. Solder beading occurs when the solder paste collapses (slump) or is pressed out of the pad during processing. During reflow, solder paste is isolated from the main deposit and collects with excess paste from other pads, either emerging from the side of the component body to form large beads, or remaining underneath the component. Solder bead elimination operations Solder beads can be avoided by taking care during fabrication by not removing them directly as far as possible.
I. Stencil
1. stencil opening directly in accordance with the size of the pad to open will also lead to tin beads in the chip processing process.
2. thickness stencil too thick, then, is also likely to cause the collapse of the solder paste, so will also produce tin beads.
3. SMT machine if mount when the pressure is too high, solder paste is easy to be squeezed to the component below the solder resist layer, in reflow soldering when the solder paste melting run to the component around the formation of tin beads.
II. Solder paste
1. Other considerations solder paste is not tempered in the preheating stage will occur in the spatter phenomenon and thus produce tin beads.
2. The smaller the size of the metal powder in the solder paste, the larger the overall surface area of the paste, resulting in higher oxidation of the finer powder, thus increasing the phenomenon of solder beads.
3. The higher the oxidation of metal powder in the solder paste, the higher the resistance of metal powder bonding during soldering, the less easy to infiltrate between the solder paste and the pad and SMT chip components, thus leading to lower solderability.
4. The amount of flux and active solder dosage is too much, it will lead to the phenomenon of local collapse of the solder paste and thus produce tin beads, the activity of the flux is not enough to completely remove the oxidation part will also lead to the chip processing factory processing processing tin beads.
5. Metal content in the actual processing of the use of solder paste general metal content and quality ratio is 88% to 92%, volume ratio of about 50%, increase the metal content can make the arrangement of metal powder become more closely, so that in the melting easier to combine.
Features of NeoDen K1830 pick and place machine
1. 8 Synchronized Nozzles which ensure a repeatable placement accuracy with high speed.
2. Machine runs on highly stable and secure Linux operating system.
3. Ethernet communication interface for all internal signal travel makes the machine to perform more stable and flexible.
4. Closed loop Servo control system with feedback makes the machine to function more accurate.
5. PCB location can be calibrated automatically and promptly,based on the correct and specific placement request.