锡膏焊接(smt工序)（Solder paste (SMT process)）
Solder paste (SMT process)
一年级手抄报简单又漂亮-----------------------------------------------------------
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北理工留学Relea date: 10:56 May 19, 2007
First, SMT process flow
Single-sided asmbly:
Material inspection: silk screen paste (point, patch, glue), patch, drying (solidification), reflow, welding, cleaning, testing, repairing
汪发良
Double sided asmbly;
A: PCB A, incoming inspection screen printing solder paste (point adhesive), patch and drying (curing), A reflow soldering, cleaning, surface turning plate, PCB B screen printing paste (point adhesive), SMD -白芍种植技术
baking reflow soldering (only for B, the best surface cleaning, detection and repair)
This process is applicable to the larger SMD, such as PLCC, on both sides of the PCB.
B: PCB A, incoming inspection screen printing solder paste (point adhesive), patch and drying (curing), A reflow soldering, cleaning, surface turning plate, PCB B glue, patch, patch point B wave soldering, solidification, surface cleaning, inspection, repair)
This process is suitable for reflow soldering on the A surface of PCB, B wave soldering. In the B asmbled on the PCB surface of the SMD, this process should be adopted only when the SOT or SOIC (28) pin is below.
Single mixing process
Incoming inspection: PCB A surface, silk screen solder paste (point, patch, glue), patch, drying (solidification), reflow, welding, cleaning, plug-in, wave soldering, cleaning, testing, rework
Double mixing process
A: incoming inspection: PCB B point, paster, glue, patch, curing, turning board, turning board, PCB, A surface inrt, wave soldering, cleaning, testing, repairing
Paste first and then inrt, apply to the SMD component more than the paration of components
育儿宝典
B: A, PCB plug-in incoming inspection (pin bending) - turning plate to a PCB B point patch glue, patch and curing - turning plate to wave soldering, cleaning, inspection and repair
浓度计算
First inrt and post, apply to parating components more than SMD components
C: PCB A, incoming inspection, screen printing paste patch - baking reflow soldering, plug, pin bending - turning plate to a PCB B point patch glue, patch and curing - turning plate to wave soldering, cleaning, inspection and repair
老外公A mixed,
B surface mount.
D: incoming inspection: PCB B point, paster, glue, patch, curing, turning board, turning plate, PCB A, solder paste, patch, A, reflow, plug, B, wave soldering, cleaning, inspection, rework
A mixed,
展望怎么写
B surface mount. First stick on both sides of the SMD, reflow soldering, after inrtion, wave soldering
E: PCB B, incoming inspection screen printing solder paste (point adhesive), patch and drying (curing), reflow soldering, turning plate, PCB A screen printing paste, patch - baking reflow soldering 1 (can be ud by local welding, soldering, plug-in) 2 (such as inrting fewer components, can the u of manual welding, cleaning, detection and repair)
Two, the role of solder paste
In the electronic process SMT process, the main role of solder paste is bonding SMD material in the PCB welding pad position, in order to ensure the placement of the patch machine, SMD material will not be scattered. At the same time, after the hot air reflow soldering, it also plays an important role in the fixation of SMD materials and connected circuits. Selection of high quality solder paste, the u of solder paste mixer fully mixing, using automatic, mi-automatic or manual solder paste printing equipment, the solder paste according to process quality requirements printed on the PCB pad. AOI (automatic optical inspection machine) check the printing paste should completely cover the PCB pad, the printing thickness should be equal to the steel mesh thickness, clear, good ejection. Otherwi
, cleaning, cleaning and re printing, the quality of solder paste printing directly affects the quality of patch material welding,
Welding quality directly affects the reliability of the product, so in the whole process of production, it is usually t as the key process. Therefore, in the machine equipment, the u of tools, materials lection, personnel skills, methods of operation, environmental conditions should meet the process requirements, in order to achieve high efficiency and good quality purpos.
Three, machinery and equipment
Solder paste mixer, automatic solder paste printing machine, mi-automatic solder paste printing machine, fingerprint desk;
Four, tools
Hand scraper, lens, magnifier, steel net;
Five, accessories
Solder paste, dust-free paper, anhydrous alcohol, alcohol bottles, gloves;
Six, anti-static
Anti-static table pad, anti-static circulation box,
anti-static asmbly box, anti-static brush;
Seven, technical points
Solder paste composition (quality), printing resolution, printing accuracy, solder paste thickness, solder paste uniformity, etc.;
Eight, commonly ud solder paste specifications
8.1 alloy composition
8.2 flux chemical composition
The chemical composition of flux mainly has following kinds:
8.3 printing
Scraper angle: 45~60 degrees as standard
