Thick Copper Boards technology

“Thick Copper Board” is defined as any circuit with a copper weight over 140 microns of copper deposit.

“PowerLink” is defined as the use of 2 or more copper weights on the same external layer of a printed wiring board.

Board Layout and Stack-up

• Balanced circuit density minimizes uneven plating and prevents poor lamination (de-lamination)

• Symmetrical construction: PCB designer can influence the warping possibility by choosing a suitable circuit board build-up. In order to achieve the best result, the build-up must be symmetrical around the centre plane of the circuit board. Asymmetrical build-ups cause warp due to differences in the CTE (Coefficient of Thermal Expansion), which cause internal stress when heating and cooling the circuit board.

• Thick copper conductors can significantly increase the overall board thickness

• Designs using “Power Link” will have an overall thickness defined by the thickest copper used

• Designs using “Power Link” required 1 drill per copper weight

• NPT holes are not affected by thick copper or “Power Link”

• Conductor lands and pads must be sized to accommodate the thick copper plating

• A baseline method of sizing conductors is based on current, temperature rise and cross-sectional area

• Optimizing the size of any conductor requires an understanding of the flow of electrical current and the resulting power dissipation

• Some variables for thermal management:

º Environment ( exposed to air, space, another gas)

º Board material properties such as: thermal conductivity, material density, fluid velocities and viscosities, thickness between layers /planes

º Number of copper planes and their thickness

º Number of plated vias, their diameter and copper weight

º Heat sources other than trace power loss


Copper weights

Cu FOIL THICKNESS AND LINE/SPACE

Outlayers

Cu thickness

Min.line width (nominal)

Min. spacing (nominal)

Base foil

Finish(galvanic)

9 µm

35 µm

50 µm

50 µm

12 µm

45-50 µm

75 µm

75 µm

18 µm

50-55 µm

100 µm

100 µm

35 µm

70 µm

150 µm

150 µm

70 µm

105 µm

250 µm

250 µm

105 µm

140 µm

300 µm

350 µm

140 µm

200 µm

400 µm

400 µm

210 µm

235 µm

500 µm

500 µm

400 µm

435 µm

900 µm

900 µm

Innerlayers

Cu foil

Min. line width

Min. spacing

9 µm

50 µm

50 µm

12 µm

75 µm

75 µm

18 µm

100 µm

100 µm

35 µm

125 µm

125 µm

70 µm

200 µm

200 µm

105 µm

250 µm

250 µm

140 µm

300 µm

350 µm

210 µm

500 µm

500 µm

400 µm

900 µm

900 µm



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