The basic elements of SMT process, including: screen printing (or dispensing), mount (curing), reflow soldering, cleaning, inspection, repair
1, screen: its role is to paste or glue were missing patches to the pad on thePCB for soldering components to prepare. Equipment used for the screen printing machine (screen printing), at the forefront of SMT production lines.
2, dispensing: it is the glue dripping onto a fixed position on the PCB's, its main role is to be fixed to the PCB board components. Equipment used for the dispenser, at the forefront of SMT production line or testing equipment behind.
3, mount: its role is to install the surface mount components to the PCB and accurate fixed position. Equipment used for the SMT, SMT production assembly line at the back of screen printing machine.
4, curing: its role is to patch plastic melting, so surface mount components and PCB board firmly bonded together. Equipment used for the curing oven, in the SMT placement machine production line in the back.
5, reflow soldering: solder paste melts its role is to make surface mount components and PCB board firmly bonded together. Equipment used for the reflow oven, in the SMT placement machine production line in the back.
6, cleaning: its role is assembled PCB board above harmful residues such as welding flux and removed. Equipment used for the washing machine, the location may not be fixed, online, or not online.
7, detection: its role is assembled PCB board assembly quality of the welding quality and testing. The equipment has a magnifying glass, microscope, line tester (ICT), flying probe tester, automatic optical inspection (AOI), X-RAY inspection system, functional tester. Position according to the needs of detection, can be configured in the production line where appropriate.
8, repair: its role is to detect failure of the pcb board to rework. The use of iron tools, rework stations and so on. Configuration in the production line anywhere.
First, single-sided pcb assembly:
Incoming test => screen printing solder paste (dot patch glue) => patch => drying (curing) => reflow soldering => Cleaning => test => Rework
Second, double-sided pcb assembly:
A: incoming inspection => PCB's A side screen printing solder paste (dot patch glue) => patch => drying (curing) => A side reflow => Cleaning => flap => PCB's B surface screen printing solder paste (dot patch glue) => patch => dry => reflow soldering (preferably only B side => Cleaning => test => Rework)
This process applies to both sides of the PCB are affixed with such a large SMD PLCC used.
B: incoming inspection => PCB's A side screen printing solder paste (dot patch glue) => patch => drying (curing) => A side reflow => Cleaning => flap => PCB's B pasta patch glue => Chip => Curing => B surface wave => Cleaning => test => Rework)
This process is suitable for reflow soldering in the PCB of the A side, B side wave soldering. In the PCB assembly SMD B-side, only the SOT or SOIC (28) pin below, should adopt this technology.
Third, single-sided mixed technology:
Incoming test => PCB's A side printing solder paste (dot patch glue) => patch => drying (curing) => reflow soldering => Cleaning => Plugins => Wave => Cleaning => test => Rework
4, double-sided mixed technology:
A: incoming inspection => PCB's B pasta patch glue => Chip => Curing => flap => PCB's A side plug-ins => Wave => Cleaning => test => Rework
Inserted after the first paste for SMD components than the situation of separated components
B: incoming inspection => PCB's A surface plug (pin bent) => flap => PCB's B pasta patch glue => Chip => Curing => flap => Wave => Cleaning => test => Rework
After the first plug paste, applied to discrete components rather than the situation of SMD components
C: incoming inspection => PCB's A side screen printing solder paste => Chip => dry => reflow soldering => plug-in, pin bent => flap => PCB's pasta patch glue = B > patch => Curing => flap => Wave => Cleaning => test => Rework A side mix, B side mount.
D: incoming inspection => PCB's B pasta patch glue => Chip => Curing => flap => PCB's A side screen printing solder paste => Chip => A side reflow => Plugins = > B surface wave => Cleaning => test => Rework A side mix, B side mount. First posted two sides SMD, reflow soldering, after instrumentation, wave soldering
E: incoming inspection => PCB B-side printing solder paste (dot patch glue) => patch => drying (curing) => reflow soldering => flap => PCB's A side screen printing solder paste => Chip => dry = reflow soldering 1 (can use local welding) => Plugins => Wave 2 (for example, plug a small device, you can use manual welding) => Cleaning => test => repair Sticking A installation, B side mixed.
Six double-sided SMT assembly process flow ---
A: incoming inspection, PCB's A side screen printing solder paste (dot patch glue), patch, drying (curing), A side reflow soldering, cleaning, flap; PCB B-side printing solder paste (point SMD plastic), patch, drying, reflow soldering (preferably only B side, cleaning, inspection, repair)
This process applies to both sides of the PCB are affixed with such a large SMD PLCC used.