smt pcb assembly process

Product Details

Technical Detail for smt pcb assembly process :

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: +/-10% Board thickness>2.0mm: +/-8%
5	Max panel size	≤2sidesPCB: 6001500mm Multilayer PCB: 5001200mm
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.

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