smt pcb assembly process
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SMT Assembly (SMA) is the term given to the process by which electronic components of various types, shapes, sizes and values are soldered to the surface of a bare printed circuit board (PCB) usually by an automated process. This process is also known as Onsertion and the general processes surrounding surface mount technology are referred to as SMT.
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Technical Detail for smt pcb assembly process :
PCB SMT Assembly Procedure
Advantage of PCB SMT Assembly in Design
1.The most important benefits in Design section are significant savings in weight and real estate and electrical noise reduction.
The SMT component can weigh as little as one-tenth of their common thru-hole equivalents. Because of this reason significant decrease in weight of the Surface Mount Assembly (SMA).
SMT components occupy small because of this only one-half to one-third of the space on the printed circuit board.
Since every electronic part are not accessible in surface mount, the real area reserves on a board will depend on the ratio of through-hole components changed by surface mount parts.
Benefits of PCB SMT Assembly in Manufacturing
There are major benefits provide also in manufacturing section.
The important advantage of SMT in manufacturing includes reduced board cost, reduced material handling costs, and a controlled manufacturing process.
Routing of traces is reduced, the size of the board is reduced, and number of drilled holes are also reduced.
If the functions on the surface mount board are not expanded, the expanded between inter-package spacing made possible by littler surface mount parts and a decrease in the quantity of bored gaps may likewise reduce the quantity of layer counts in the printed circuit board. This will again bring down the board cost.
The above benefits of Surface Mount Technology don’t necessarily means that SMT assembly will always cost less. It depends when and how SMT is used.
Disadvantages of smt pcb assembly process
• The small lead spaces can make repairs more difficult.
• It cannot assurance that the solder connections will withstand the compounds used during potting application. The connections may or may not be damaged when going through thermal cycling.
• Components that generate a lot of heat or bear a high electrical load cannot be mounted using SMT because the solder can melt under high heat.
• The solder can also be weakened due to mechanical stress. This means components that will be directly interacting with a user should be attached using the physical binding of through-hole mounting.
Related Products:
Workshop :
Exhibition:
Contact Detail:
Foreign Sale :Rainbow
Email:sales5@xdpcba.com
Skype:xingdapcbsales5
Tel:86-0755-29621535 Ext:817
| XD Electronic Technology Co.,LTD | ||||
| Seq | Item | capability | ||
| 1 | Base Material | FR-4, High TG FR-4 , Halogen Free material ,CEM-3,CEM-1,PTFE,Rogers ,Arlon ,Taconic,Aluminum base,Teflon,PI ,etc | ||
| 2 | Layers | 1-38 ( ≥30 layers needs review ) | ||
| 3 | Finished inner/outer copper thickness | 0.5-12OZ | ||
| 4 | Finished board thickness | 0.2-7.0mm(≤0.2mm needs review),≤0.4mm for HASL | ||
| Board thickness≤1.0mm: +/-0.1mm 1 Board thickness>2.0mm: +/-8% | ||||
| 5 | Max panel size | ≤2sidesPCB: 600*1500mm Multilayer PCB: 500*1200mm | ||
| 6 | Min conductor line width/spacing | Inner layers: ≥3/3mil Outer layers: ≥3.5/3.5mil | ||
| 7 | Min hole size | Mechanical hole: 0.15mm Laser hole: 0.1mm | ||
| Drilling precision: first drilling First drilling: 1mil Second drilling: 4mil | ||||
| 8 | Warpage | Board thickness≤0.79mm: β≤1.0% 0.80≤Board thickness≤2.4mm: β≤0.7% Board thickness≥2.5mm: β≤0.5% | ||
| 9 | Controlled Impedance | +/- 5 % Ω(<50Ω),+/-10%(≥50Ω),≥50Ω+/-5% (needs review) | ||
| 10 | Aspect Ratio | 15:01 | ||
| 11 | Min welding ring | 4mil | ||
| 12 | Min solder mask bridge | ≥0.08mm | ||
| 13 | Plugging vias capability | 0.2-0.8mm | ||
| 14 | Hole tolerance | PTH: +/-3mil NPTH: +/-2mil | ||
| 15 | Outline profile | Rout/ V-cut/ Bridge/ Stamp hole | ||
| 16 | Solder mask color | Green,yellow,black,blue,red,white,matte green | ||
| 17 | Component mark color | white,yellow,black | ||
| 18 | Surface treatment | OSP: 0.2-0.5um HASL: 2-40um Lead free HASL: 2-40um ENIG: Au 1-10U’’ ENEPIG: PB 2-5U’’/ Au 1-8U’’ Immersion Tin:0.8-1.5um Immersion silver: 0.1-1.2um Peelable blue mask Carbon ink Gold plating: Au 1-150U’’ | ||
| 19 | E-Test | Flying probe tester : 0.4-6.0mm,max 19.6*23.5inch | ||
| Min spacing from test pad to board edge : 0.5 mm | ||||
| Min conductive resistance : 5 Ω | ||||
| Max insulation resistance : 250 MΩ | ||||
| Max test voltage : 500 V | ||||
| Min test pad diameter : 6 mil | ||||
| Min test pad to pad spacing : 10 mil | ||||
| Max test current : 200 MA | ||||
| 20 | AOI | Orbotech SK-75 AOI : 0.05-6.0mm,max 23.5*23.5inch | ||
| Orbotech Ves machine : 0.05-6.0mm,max 23.5*23.5inch | ||||
PCB SMT Assembly Procedure
Advantage of PCB SMT Assembly in Design
1.The most important benefits in Design section are significant savings in weight and real estate and electrical noise reduction.
The SMT component can weigh as little as one-tenth of their common thru-hole equivalents. Because of this reason significant decrease in weight of the Surface Mount Assembly (SMA).
SMT components occupy small because of this only one-half to one-third of the space on the printed circuit board.
Since every electronic part are not accessible in surface mount, the real area reserves on a board will depend on the ratio of through-hole components changed by surface mount parts.
Benefits of PCB SMT Assembly in Manufacturing
There are major benefits provide also in manufacturing section.
The important advantage of SMT in manufacturing includes reduced board cost, reduced material handling costs, and a controlled manufacturing process.
Routing of traces is reduced, the size of the board is reduced, and number of drilled holes are also reduced.
If the functions on the surface mount board are not expanded, the expanded between inter-package spacing made possible by littler surface mount parts and a decrease in the quantity of bored gaps may likewise reduce the quantity of layer counts in the printed circuit board. This will again bring down the board cost.
The above benefits of Surface Mount Technology don’t necessarily means that SMT assembly will always cost less. It depends when and how SMT is used.
Disadvantages of smt pcb assembly process
• The small lead spaces can make repairs more difficult.
• It cannot assurance that the solder connections will withstand the compounds used during potting application. The connections may or may not be damaged when going through thermal cycling.
• Components that generate a lot of heat or bear a high electrical load cannot be mounted using SMT because the solder can melt under high heat.
• The solder can also be weakened due to mechanical stress. This means components that will be directly interacting with a user should be attached using the physical binding of through-hole mounting.
Related Products:
Workshop :
Exhibition:
Contact Detail:
Foreign Sale :Rainbow
Email:sales5@xdpcba.com
Skype:xingdapcbsales5
Tel:86-0755-29621535 Ext:817
