SMT reflow oven is an essential soldering equipment in the SMT process, which is actually a combination of a baking oven. Its main function is to let the paste solder in the reflow oven, the solder will be melted at high temperatures after the solder can make the SMD components and circuit boards together in a welding equipment. Without SMT reflow soldering equipment SMT process is not possible to complete so that the electronic components and circuit board soldering work. And SMT over the oven tray is the most important tool when the product over the reflow soldering, see here you may have some questions: SMT over the oven tray is what? What is the purpose of using SMT overbake trays or overbake carriers? Here’s a look at what the SMT overbake tray really is.
1. What is the SMT overbake tray?
The so-called SMT over-burner tray or over-burner carrier, in fact, is used to hold the PCB and then take it to the back to the soldering furnace tray or carrier. Tray carrier usually has a positioning column used to fix the PCB to prevent it from running or deformation, some of the more advanced tray carrier will also add a cover, usually for FPC, and install magnets on, download the tool when the suction cup fastening with, so SMT chip processing plant can avoid PCB deformation.
2. The use of SMT over the oven tray or over the purpose of the oven carrier
SMT production when using over the oven tray is to reduce PCB deformation and prevent overweight parts fall, both of which are actually related to the SMT back to the high temperature area of the furnace, to the vast majority of products now using lead-free process, lead-free SAC305 solder paste molten tin temperature of 217 ℃, and SAC0307 solder paste molten tin temperature falls about 217 ℃ ~ 225 ℃, the highest temperature back to the solder are generally Recommended in between 240 ~ 250 ℃, but for cost considerations, we generally choose the FR4 plate for Tg150 above. That is to say, when the PCB enters the high temperature area of the soldering furnace, in fact, it has long exceeded its glass transfer temperature into the rubber state, the rubber state of the PCB will be deformed only to show its material characteristics just right.
Coupled with the thinning of the board thickness, from the general thickness of 1.6mm down to 0.8mm, and even 0.4mm PCB, such a thin circuit board in the baptism of high temperature after the soldering furnace, it is easier because of the high temperature and the board deformation problem.
SMT over the oven tray or over the oven carrier is to overcome the PCB deformation and parts falling problems and appear, it generally uses the positioning pillar to fix the PCB positioning hole, in the plate high temperature deformation to effectively maintain the shape of the PCB to reduce the plate deformation, of course, there must also be other bars to assist the middle position of the plate because of the impact of gravity may bend the problem of sinking.
In addition, you can also use the overload carrier is not easy to deform the characteristics of the design of ribs or support points below the overweight parts to ensure that the parts do not fall off the problem, but the design of this carrier must be very careful to avoid excessive support points to lift the parts caused by the second side of the inaccuracy of the solder paste printing problem occurs.
Post time: Apr-06-2022