Multilayer

Features manufacture multilayer and General tolerances

High level complexity and minimizing the space for the printed circuit boards have been the main reasons for the strong development of multiple layers printed circuit boards. The increase in the manufacturing of this kind of printed circuit boards has been constant in Lab Circuits during the last years. The classic structure of a multiple layers printed circuit board has some cores –that have the ground and signal inner layers- and the conventional component and solder faces in the outside. The cores are made by a FR4 material sheet (glass fibre and epoxy resin with two external copper layers).

The core has its own body in the manufacture process until the multilayer pressing moment takes part, this means, it goes through a dry film process, exposure and a chemical process to end up creating one only structure that combines the cores with the prepreg sheets (glass fibre fabric impregnated with epoxy resin) and external covering copper sheets. This union is achieved by high temperature lamination pressing process.

Once it has been pressed, this structure has the same process as a double-sided printed circuit board.

PARAMETERS MANUFACTURE MULTILAYER

CLASS 3 CLASS 4 CLASS 5 CLASS 6 CLASS 7
Minimum plated through hole diameter 0,50 mm
0,30 mm 0,30 mm
0,20 mm 0,15 mm
Minimum non plated through hole diameter 0,60 mm 0,40 mm 0,40 mm 0,30 mm 0,25 mm
Aspect / Ratio 5 5 6 8 13 (maximun
thickness 2 mm)
Minimum outerlayer trace / spacing width 0,30 mm (17 µ m)
0,30 mm (35 µ m)
0,35 mm (70 µ m)
0,20 mm (17 µ m)
0,20 mm (35 µ m)
0,25 mm (70 µ m)
0,15 mm (17 µ m)
0,15 mm (35 µ m)
0,20 mm (70 µ m)
0,125 mm (17 µm)
0,15 mm (35 µm)
0,175 mm (70 µm)
0,100 mm (17 µ)
Minimum innerlayer trace / spacing width 0,25 mm (17 µ m)
0,30 mm (35 µ m)
0,30 mm (70 µ m)
0,15 mm (17 µ m)
0,20 mm (35 µ m)
0,20 mm (70 µ m)
0,125 mm (17 µ m)
0,15 mm (35 µ m)
0,175 mm (70 µ m)
0,10 mm (17 µ m)
0,125 mm (35 µ m)
0,15 mm (70 µ m)
0,075 mm (17 µ m)
0,100 mm (35 µ m)
Minimum Outer layer annular ring 0.22 mm 0.17 mm 0.13 mm 0.10 mm 0.075 mm
Minimum Signal inner layer annular ring 0.25 mm 0.22 mm 0.19 mm 0.15 mm 0.125 mm
Minimum annular spacing in ground plane 0.40 mm 0.40 mm 0.30 mm 0.25 mm 0.20 mm
Minimum microvia diameter 0,10 mm
(max. thickness 0.1 mm)
0,075 mm
(max. thickness 0.065 mm)
0,075 mm
(max. thickness
0.065 mm)
Microvia surface pad 0.35 mm 0.30 mm 0.25 mm
Microvia landing pad 0.30 mm 0.25 mm 0.25 mm
Minimum wall between
microvia and thru hole / blind/ buried
0.22 mm 0.15 mm 0.10 mm
Minimum wall between microvias 0.23 mm 0.15 mm 0.10 mm
Minimum wall between microvias in two levels 0.23 mm 0.15 mm 0.10 mm

Last update: 13-02-2012
Units: Milimeters

CLASS 3 CLASS 4 CLASS 5 CLASS 6 CLASS 7
Minimum plated through hole diameter Minimum plated through hole diameter 20 mil 12 mil 12 mil 8 mil 6 mil
Minimum non plated through hole diameter Minimum non plated through hole diameter 24 mil 16 mil 16 mil 12 mil 10 mil
Aspect / Ratio Aspect/Ratio 5 5 6 8 13 (maximun
thickness 80 mils)
Minimum outerlayer trace / spacing width Minimum outerlayer trace/spacing width 12 mil (½ oz)
12 mil (1 oz)
14 mil (2 oz)
8 mil (½ oz)
8 mil (1 oz)
10 mil (2 oz)
6 mil (½ oz)
6 mil (1 oz)
8 mil (2 oz)
5 mil (½ oz)
6 mil (1 oz)
7 mil (2 oz)
4 mil (½ oz)
Minimum innerlayer trace / spacing width Minimum innerlayer trace/spacing width 10 mil (½ oz)
12 mil (1 oz)
12 mil (2 oz)
6 mil (½ oz)
8 mil (1 oz)
8 mil (2 oz)
5 mil (½ oz)
6 mil (1 oz)
7 mil (2 oz)
4 mil (½ oz)
5 mil (1 oz)
6 mil (2 oz)
3 mil (½ oz)
4 mil (1 oz)
Minimum Outer layer annular ring Minimum Outer layer annular ring 9 mil 7 mil 5 mil 4 mil 3 mil
Minimum Signal inner layer annular ring Minimum Signal inner layer annular ring 10 mil 9 mil 8 mil 6 mil 5 mil
Minimum annular spacing in ground plane Minimum annular spacing in ground plane 16 mil 16 mil 12 mil 10 mil 8 mil
Minimum microvia diameter Minimum diameter microvia 4 mil
(max. thickness
4 mils)
3 mil
(max. thickness
3 mils)
3 mil
(max. thickness 3 mils)
Microvia surface pad Microvia surface pad 14 mil 12 mil 10 mil
Microvia landing pad Microvia landing pad 12 mil 10 mil 10 mil
Minimum wall between
microvia and through hole / blind/ buried
Minimum wall between 
microvia and through hole / blind/ buried 9 mil 6 mil 4 mil
Minimum wall between microvias Minimum wall  between microvias 9 mil 6 mil 4 mil
Minimum wall between microvias into consecutive levels Minimum wall between microvias into consecutive levels 9 mil 6 mil 4 mil

Last update: 13-02-2012
Units: Mils

MULTILAYER GENERAL TOLERANCES

STANDARD SPECIAL
Outer layer trace / spacing width ±25% (35-70 µm)
±20% (17 µm )
±15% (35-70 µm)
±10% (17 µm)
Inner layer trace / spacing width ±25% (70 µm )
±20% (17-35 µm )
±15% (35-70 µm)
±10% (17 µm)
Plated hole diameter +0,10 mm / -0,05 mm
(or equivalent)
+0,10 mm / -0,0 mm
(or equivalent)
Non plated hole diameter +0,10 mm / -0,0 mm
(or equivalent)
±0,035 mm
(or equivalent)
Scoring to copper clearance Min. 1,0 mm. Min. 0,75 mm.
Scoring positioning ±0,10 mm ±0,075 mm
Scoring remaining thickness ±0,15 mm
±0,075 mm
Board size ± 0,15 mm.
± 0,10 mm.
Total thickness tolerance ±10 % ±5 %
Dielectric thickness ±10 % ±5 %
Finished plated hole copper thickness Average: 25 µm
Minim: 20 µm
Average: 35 µm
Mínim: 30 µm
Blind/buried plated hole copper thickness Average: 15 µm
Minimum: 13 µm
Average: 25 µm
Minimum: 20 µm

Microvia Plated hole copper thickness Average: 12 µm
Minimum:10 µm

Average: 12 µm
Minimum:10 µm
Mínimum wall between same net plated through holes 0.30 mm 0.25 mm
Minimum wall between different net plated through holes 0,40 mm. 0,35 mm.
Minimum wall between non plated thruough holes 0,25 mm. 0,20 mm.
Minimum annular ring non plated hole 0,25 mm
0,20 mm
Track to non plated through hole minimum spacing 0,20 mm
0,15 mm
Track to board edge minimum spacing 0,20 mm
0,15 mm
Offset between board edge and drill Max. 0,15 mm.
Max. 0,10 mm.
Offset between drill to outlayer pad Max. 0,10 mm.
Max. 0,075 mm.
Offset between drill to innerlayer pad Max. 0,15 mm. Max. 0,12 mm.
Offset between layers Max. 0,10 mm.
Max. 0,075 mm.
Soldermask feature tolerance Max. 0,15 mm. Max. 0,075 mm.
Soldermask min Dam size 0.08 mm green color
other colors on request
--
Photoimageable soldermask clearance 0.06 mm --
Silkscreened soldermask clearance 0,20 mm
0,15 mm
Legend minimum line 0,125 mm
0,10 mm
Conductive ink (graphite) overlapping 0,20 mm
0,125 mm
Conductive ink (graphite) spacing 0,50 mm 0,40 mm
Conductive ink to pad spacing 0,40 mm 0,30 mm
Peel-off mask overlapping 0.8 mm
0,50 mm
Peel-off mask to pad spacing 1 mm 0,70 mm
Peel-off mask to board
edge spacing
1 mm 0,70 mm
Maximum peel-off mask filled hole 1.80 mm 2 mm
Bow and twist spacer Maxim 1% Maxim 0,5 %
Insulation resistance spacer Minim 0,5 MOhm Minim 2,0 MOhm
Continuity spacer Maxim 10 Ohms -
Ionic contamination spacer Max. 1µg Eq. CINa/cm2 Max. 0,8 µg Eq. CINa/cm2
Other features spacer See spec.
IPC-A-600 Rev.G jul-04
-

Last update: 20-09-2016
Units: Milimeters

STANDARD SPECIAL
Outer layer trace / spacing width Outer layer trace/spacing width ±20% (½ oz )
±25% (1-2 oz )
±10% (½ oz )
±15% (1 - 2 oz)
Inner layer trace / spacing width Inner layer trace/spacing width ±20% (½ - 1 oz)
±25% (2 oz)
±10% (½ oz )
±15% (1 - 2 oz )
Plated hole diameter Plated hole diameter +4 mil / -2 mil
(or equivalent)
+4 mil / -0,0 mil
±2 mil
Non plated hole diameter Non plated hole diameter +4 mil / -0,0 mil
(or equivalent)
±1.4 mil
(or equivalent)
Scoring to copper clearance Scoring to copper clearance Min. 40 mil. Min. 30 mil
Scoring positioning Scoring positioning ± 4 mil ± 3 mil
Scoring remaining thickness Scoring remaining thickness ± 4 mil
± 2 mil
Board size Board size ± 6 mil.
± 4 mil.
Total thickness tolerance Total thickness tolerance ±10 % ±5 %
Dielectric thickness Dielectric thickness ±10 % ±5 %
Finished plated hole copper thickness Finished plated hole copper thickness Average: 0.7 oz
Minimum: 0.6 oz
Average: 1 oz
Minimum: 0.86 oz
Blind/buried plated hole copper thickness Blind/buried plated hole copper thickness Average: 0.4 oz.
Minimum: 0.37 oz.
Average : 0.7 oz.
Minimum: 0.6 oz.
Microvia Plated hole copper thickness Microvia Plated hole copper thickness Average: 0.4 oz.
Minimum:0.37 oz.

Average: 0.7 oz.
Minimum: 0.6 oz.

Mínimum wall between same net plated through holes Mínimum wall between same net plated through holes 12 mil. 10 mil.
Minimum wall between different net plated through holes Minimum wall between different net plated through holes 16 mil. 14 mil.
Minimum wall between non plated thruough holes Minimum wall between non plated thruough holes 10 mil. 8 mil.
Minimum annular ring non plated hole Minimum annular ring non plated hole 10 mil.
8 mil.
Track to non plated through hole minimum spacing Track to non plated through hole minimum spacing 8 mil. 6 mil.
Track to board edge minimum spacing Track to board edge minimum spacing 8 mil. 6 mil.
Offset between board edge and drill Offset between board edge and drill Max. 6 mil.
Max. 4 mil.
Offset between drill to outlayer pad Offset between drill to outlayer pad Max. 4 mil.
Max. 3 mil.
Offset between drill to innerlayer pad Offset between drill to innerlayer pad Max. 6 mil. Max. 5 mil.
Offset between layers Offset between layers Max. 4 mil.
Max. 3 mil.
Soldermask feature tolerance Soldermask feature tolerance Max. 6 mil. Max. 3 mil.
Soldermask min Dam size Soldermask min Dam size 3.15 mil. green color
other colors on request
--
Photoimageable soldermask clearance Photoimageable soldermask clearance 2.5 mil. --
Silkscreened soldermask clearance Silkscreened soldermask clearance 8 mil. 6 mil.
Legend minimum line Legend minimum line 5 mil. 4 mil.
Conductive ink (graphite) overlapping Conductive ink (graphite) overlapping 8 mil.
5 mil.
Conductive ink (graphite) spacing Conductive ink (graphite) spacing 20 mil. 16 mil.
Conductive ink to pad spacing Conductive ink to pad spacing 16 mil. 12 mil.
Peel-off mask overlapping Peel-off mask overlapping 32 mil. 20 mil.
Peel-off mask to pad spacing Peel-off mask to pad spacing 40 mil. 28 mil.
Peel-off mask to board
edge spacing
Peel-off mask to board 
edge spacing 40 mil. 28 mil.
Maximum peel-off mask filled hole Maximum peel-off mask filled hole 71 mil. 79 mil.
Bow and twist spacer Maxim 1% Maxim 0,5 %
Insulation resistance spacer Minimum 0,5 MOhm Minimum 2,0 MOhm
Continuity spacer Maxim 10 Ohms -
Ionic contamination spacer Max. 1µg Eq. CINa/cm2 Max. 0,8 µg Eq. CINa/cm2
Other features spacer See spec.
IPC-A-600 Rev.E 8-95
-

Last update: 20-09-2016
Units: Mils