Double-layer printed circuits

Double-layer printed circuits

Nowadays, double-layer printed circuit technology is perhaps the most popular type of PCB in the industry and they support advanced technology applications.

The main applications for this type of printed circuit include: industrial controllers, power sources, converters, control relays, instruments, energy conversion systems, LED lighting, hard drives, printers, telephone systems, energy control systems, line reactors, amplifiers, traffic systems, vending machines, etc.

The main advantages of this type of circuit include:

- Greater flexibility for designers.

- Higher circuit density.

- Relatively low costs.

- Intermediate circuit complexity.

- Reduced circuit size (which reduces costs).

CHARACTERISTICS IMAGE CATEGORY 3 CATEGORY 4 CATEGORY 5 CATEGORY 6 CATEGORY 7
Minimum metallic hole. 0.7 0.5 0.4 0.3 0.2
Minimum NON metallic hole. 0.8 0.6 0.5 0.4 0.3
Ratio between circuit thickness and hole. 3 5 10 15 15
Minimum track width on external layers. 0.250 0.200 0.150 0.125 0.100
Minimum space between tracks on external layers. 0.250 0.200 0.150 0.125 0.100
Minimum distance between crown and hole on external layers. 0.250 0.200 0.150 0.125 0.100
Maximum error in slot position. 0.125 0.125 0.125 0.125 0.100
Tolerances for slot nerve. ±0.2 ±0.2 ±0.2 ±0.2 ±0,150
Contour dimensions ±0,150 ±0,150 ±0,150 ±0,150 ±0,100
Minimum tolerances between conductors for slotting. 1.0 1.0 1.0 1.0 0.8
End thickness. ±0,100 ±0,100 ±0,100 ±0,100 ±0.75
Metallisation thickness in through hole. >0.020 >0.020 >0.020 >0.020 >0.025
Minimum wall between NON metallic holes. 0.250 0.250 0.250 0.250 0.200
Minimum crown for NON metallic hole. 0.300 0.250 0.250 0.250 0.200
Minimum distance between conductor and NON metallic hole. 0.200 0.200 0.200 0.200 0.150
Minimum distance between conductor and contour. 0.200 0.200 0.200 0.200 0.125
Maximum deviation between contour and hole. 0.200 0.200 0.200 0.200 0.125
Maximum deviation between pad and hole (EXTERNAL faces). 0.100 0.100 0.100 0.100 0.075
Maximum deviation between copper and photosensitive mask. 0.150 0.150 0.150 0.150 0.075
Minimum photosensitive ink stroke. 0.100 0.100 0.100 0.100 0.075
Minimum allowance for photosensitive ink. 0.075 0.075 0.075 0.075 0.050
Minimum width for legend trace. 0.150 0.150 0.150 0.150 0.125
Minimum allowance for graphite ink. 0.200 0.200 0.200 0.200 0.150
Minimum space between graphite ink. 0.450 0.450 0.450 0.450 0.350
Minimum allowance between graphite and conductor. 0.350 0.350 0.350 0.350 0.300
Minimum allowance for peelable ink. 0.900 0.900 0.900 0.900 0.700
Minimum distance between pad and peelable ink. 0.900 0.900 0.900 0.900 0.700
Minimum distance between contour and peelable ink. 0.900 0.900 0.900 0.900 0.700
Maximum diameter for hole covered with peelable ink. 1.90 1.90 1.90 1.90 2.10