Surface copper foil:
There are three types of surface copper foil materials that can be used: 12um, 18um and 35um. The final thickness after processing is about 44um, 50um and 67um, roughly equivalent to copper thickness of 1 OZ, 1.5 OZ, 2 OZ. Note: When using the impedance calculation software for impedance control, the copper thickness of the outer layer is not 0.5 OZ. The following are the same as the "
Core board: Our commonly used plate is S1141A, the standard FR-4, two-sided copper, optional specifications can be determined with the manufacturer to contact. Prepreg:
(Thickness of the original thickness) is 7628 (0.185mm / 7.4mil), 2116 (0.105mm / 4.2mil), 1080 (0.075mm / 3mil), 3313 (0.095mm / 4mil), the actual thickness is usually Value is about 10-15um (ie 0.5-1mil), so the minimum dielectric thickness of the laminated design should not be less than 3mil. The same wetting layer can use up to three prepregs, and the thickness of the three prepregs can not be the same, at least one can only use a prepreg, but some manufacturers must use at least two. If the thickness of the prepreg is not enough, the copper foil on both sides of the core can be etched away, and then the braze is adhered on both sides with a prepreg so that a thicker wetting layer can be achieved. The dielectric constant of the prepreg is related to the thickness, and the following table shows the thickness and dielectric constant of the different types of prepreg:
The dielectric constant of the sheet is related to the resin material used, and the FR4 sheet has a dielectric constant of 4.2-4.7 and decreases as the frequency increases.
Solder layer of 6l multilayer: the thickness of the solder layer above the copper foil C2 ≈ 8-10 um, the surface of the copper foil area of the solder layer thickness C1 according to the surface of the different copper thickness, when the surface copper thickness of 45um C1 ≈ 13-15um , When the surface copper thickness of 70um when C1 ≈ 17-18um, calculated with SI9000, the thickness of the solder mask can take 0.5OZ. Wire cross section: Due to the corrosion of the copper foil, the cross section of the wire is not a rectangle and is actually a trapezoid. To TOP layer, for example, when the copper foil thickness of 1OZ, the trapezoidal upper edge than the bottom edge of the short 1MIL. Such as line width 5MIL, then its bottom edge of about 4MIL, under the bottom 5MIL. The difference between the upper and lower bottom edges is related to the copper thickness. The following table shows the relationship between the upper and lower trapezoidal traps in different situations.
|Line Width||Copper thickness(OZ)||Line Width（Mil）||Line Width（Mil)|