FR4 Printed Circuit Boards 6 Layer PCB Middle TG Degree

Printed Circuit Boards 6 Layer PCB Middle TG Degree FR4 Material

Specifications:

1 All dimensions are in MM.

2 Fabricate per IPC-6012A Class2.

3 Materials:

3.1 Dielectric: FR4 Per IPC or equivalent

3.2 Min Tg: 150DEG

3.3 Copper: As per stack up

3.4 UL Rating: 94V0 Minimum

4 Surface finish: ENIG

5 Solder mask material should meet all requirement of the IPC-SM-840E and shall be green in color and applied over bare copper. Vendor may edit solder mask and paste mask as needed.

6 Editing of existing copper layers shall require customer approval.

7 Silkscreen legend to be applied per layer stackup using white non-conductitive epoxy ink.

8 100% continuity testing using database netlist shall be performed.Vendor to identify test passed in secondary side.

9 Vendor to mark date code and logo in legend secondary side.

10 Bow and twist shall not exceed 1.0% of longest side.

11 Vendor to provide panel drawing for customer approval before production

Packing Specifications:

1 One vacuum pcb package should not be over 25 panels based on panel size.

2 The vacuum pcb package sealed must be free to tear, hole or any defects that may cause leakage.

3 The pcb package must be suitable to ensure effective vacuum sealing.

4 Every package must have desiccant and humidity indicator card on the inside of vacuum package.

5 Humidity indicator card target less than 10%.

FQA:

Q1: What is the Thermal Resistance of a PCB?

A1:  Thermal Resistance is a property of a printed circuit board that specifies its resistance to heat dispersion. A low thermal resistance in a PCB makes the dispersion of heat easier. This is basically the inverse of thermal conductivity. The thermal resistance of a PCB can be calculated by evaluating all the layers of the board and the heat parameters of the material.

To find the total thermal resistance for your board, you must include all layers of the board and the associated heat parameters for the type of material through which heat will flow.

[Formula]

R_theta = absolute thermal resistance (K/W) across the thickness of the sample

Delta x = thickness (m) of the sample (measured on a path parallel to the heat flow)

k = thermal conductivity (W/(K·m)) of the sample

A = cross-sectional area (m2) perpendicular to the path of heat flow

In addition to the thermal resistance of the board. The Thermal resistance of Vias must also be calculated. This usually depends on the copper trance, the laminate and the substrate and their respective thermal resistivities.

How can you reduce the Thermal Resistance of a PCB?

Thermal resistance can be reduced by increasing the thickness of the copper traces.
Another method to decrease the thermal resistance is to place copper pads below the hot components. The high thermal conductivity of copper provides a low resistance path for the dispersion of heat. These pads can be connected to an internal ground plane through vias, which have good thermal conductivity and thus help move heat away from the component.
Using Heat Sinks can help lower the thermal resistivity of the board.