Track width

 

The Track Width (TW) is specified in mm and is one of the parameters that determines the pattern class of the board.

A typical TW value is 0.150mm or 6mil. This is the value for our pattern class 6 our standard.

We define OTW as Outer layer Track Width and ITW as Inner layer Track Width

 

 

 

See Eurocircuits Classification.

OTW or Outer layer Track Width

 

 

 

 

 

Outer layer track width

 

 

A : Resist width determined by the production master width.
B : Conductor base: position where the min. conductor width is measured.
C : Point of narrowest conductor width.
D : Cu-foil thickness.
E : Undercut.
F : Out growth (Fmax = A/8).
G : Overhang.

Etch-factor (D/E) >1

 

 

 

 

ITW or Inner layer Track Width

 

 

 

 

 

 

Inner layer trackwidth

 

 

 

A : Resist width determined by the production master width
B : Conductor base: position where the min. conductor width is measured.
C : Point of narrowest conductor width.
D : Cu-foil thickness.
E : Undercut

 

Etch-factor (D/E) >1

 

 

 

Track Width as defined by Eurocircuits

Track width may not be reduced to less than 75 % of the nominal value.

R1 > 0.75 A1

R2 + R3 > 0.75 A2

The diameter of the HMT, Hole Mounted Technology, or SMT, Surface Mounted Technology, solder pad may not be reduced to less than 75 % of the nominal value.

Edge definition

acceptable unevenness (U)(crest to trough) regarding track width and spacing.

Edge definition

 

 

 

 

 

nom. TT/TW

U

120 µ

30 µ

150 µ

38 µ

200 µ

50 µ

300 µ

75 µ

500 µ

100 µ

 

Indentations and projections and what we allow and what not.

Indentations

 

 

 

 

  • The depth (D) must be less than 1 mm.
  • The height (H) must be less than 1 mm.
  • The length (L) of an indentation or a projection must not
    exceed 2 mm.

Note : 75% rule implies that 1 mm indentions and projections are only acceptable for TT/TW > 4 mm.

 

 

 

Indentations on pads

  • The length (L) shall not exceed 2 mm.
  • For HMT-pads : (L) max 25% of circumference.
    For SMT-pads : (L) max 25% of each edge.
  • The average number of defects must not exceed 1 defect per 50 mm edge length.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nodules

Nodules (symptom of incorrect plating) must not occur.

 

 

 

 

 

 

 

 

 

 

 

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