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Electronic Design

Electronic Design

Electronic Design

Electronic Design

Circuit board design specification-thick copper board design specification
2021-10-06
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Author:Aure

Circuit board design specification-thick copper board design specification


For PCB circuit boards with a copper thickness of more than 2 ounces, due to the copper thickness, the circuit board design specifications are different from general circuit boards. For this reason, the company specially designates a document inspection specification for thick copper boards so that customers can Provide better quality circuit boards.

1: Wire design specification for circuit board design
A: The minimum wire width of the circuit board is not less than 0.3mm;
B: In general, the distance between adjacent wires should not be less than 0.25mm
C: The copper foil around the fixing hole is not less than 0.4mm from the edge of the hole; there should be no thin wire 1.5mm from the edge of the hole
E: Whether to consider low-density wiring design
F: Whether the wires are laid out according to the shortest route, and whether there will be no sharp angles at the turn
G: Whether the junction between the wire and the pad is smoothed into a slope
H: In the power circuit, the distance between adjacent wires between hot and cold ground should not be less than 6mm
I: The distance between the wire and the edge of the printed board is generally not less than 3mm, especially not less than 1.5mm, but the wiring width must not be less than 1.5mm; the ground wire must not be less than 0.5mm


Circuit board design


2: Design specification of pads for circuit board design

A: The distance between the pad of the interposing component and the edge of the printed board is generally not less than 7mm, especially not less than 3.5mm. The distance between the pad and the edge of the mounted component should not be less than 5mm; The physical and pad distance of the interposing component or the mounting component should not be less than 5mm from the edge of the board
B: For ICs with a 1.78mm pin pitch, the connection (pad) pitch should not be less than 0.3mm
C: The minimum diameter of the circular pad, whether it meets the standard
D: After the wave soldering of the components inserted, whether the pads are driven away from the tin bath
E: There must be no connection between the pads, between the pads and the exposed copper foil
F: Whether the pads of the switching transformer and the harmonic current suppressor are removed from the empty pads to prevent mis-insertion
G: The filter inductance of the AC input circuit, whether the pads of the switching transformer, inverter transformer, high-power resistor, high-power damping or rectifier straddle diode (non-plastic package), and rectifier large electrolytic capacitor are reinforced with rivets
H: The number of rivet pads of multi-pin component pads, generally should not be less than 1/2 of the number of pins of the component
I: Whether the design requirements of the rivet hole pad meet the standard; the rivet pad with a 1.8mm aperture is 4.5mm. If it does not meet the requirements, a 4.0mm pad must be used and a droplet-shaped upper tin reinforcement is required. The rivet pad with a 2.4mm aperture is 5.5mm, if not satisfied, use 5.0mm pad and add drop-shaped upper tin reinforcement
J: Take the printed board positioning hole as the center, no rivet pads are designed within a radius of 7mm, and rivet pads are not designed for adjacent holes with a distance of less than 6mm
H: Whether the key components are reinforced with rivets, and whether the pads of the key components are tinned with water droplets

3: Thermal design specifications for circuit board design

A: Whether the thermal element is far away from the heat sink
B: Are there heat dissipation measures for high-power components?
C: The distance between the high-power heating device and the large-volume electrolytic capacitor must be greater than 5mm
D: Have you considered the heat conduction facilities of the device?
E: Is the fixation and location of the radiator appropriate?
F: The heating device should have a proper amount of heat dissipation holes under and around the corresponding printed board, and the diameter is generally not greater than 4mm
G: Large-area copper foil is easy to be heated to produce copper foil expansion, and the area exceeds the diameter of the 15mm circle, the conductive layer must be opened with a conductive window

4: Layout design specifications for circuit board design

A: Is it possible to complete production through the simplest assembly process?
B: Whether the layout of the high-power devices is uniform, whether the heat dissipation flow direction is considered, and the board strength
C: Is the fixing device added to the high-quality device?
D: Have you considered the insulation measures of the device?
E: Whether the arrangement of components is horizontal or vertical
F: The radiator must not touch the surrounding components
G: Whether the design of the cushion position is evenly distributed
H: Whether there are nail bottom components and flying leads
I: Whether the heat sink installation complies with the heat dissipation flow direction, and whether to use the existing heat sink as much as possible to reduce the possibility of making a new heat sink
J: Whether the maximum PCB board length is not more than 600mm, and the width is not more than 360mm
K: Are there grounding lugs at the fixed holes for cold ground installation? Is the grounding lug sufficient?
L: Whether there are more than three global Mark points on the copper foil surface of the board, and whether the increased position meets the process requirements and affects the safety distance
M: Whether the arrangement of the vertical electrical plug-in components can ensure that the outer edge distance between the pieces is more than 1mm
N: Whether there are solder pads and copper foil on the edge of the printed board, making assembly more difficult
O: Whether the vertical board considers the fixing method
P: Whether the components fixed on the heat sink leave a space that can be disassembled without disassembling the heat sink
Q: Are there tall and dense components or sharp radiator corners around the power strip?
R: Whether the placement position of the input and output power strips meets the convenience of connecting with other boards of the whole machine
S: Whether the SMD components are placed perpendicular to the long side of the board to avoid fracture or damage due to deformation
T: Whether the plug-in IC and the chip IC are placed horizontally and the direction of the wave soldering is consistent with the wave soldering process, and whether the IC is designed with tin-theft pads in the appropriate position during the wave soldering to avoid continuous soldering of the soldering pads
U: Whether to consider avoiding shadow effects when placing all SMD components
V: Is there any positional interference between the screws of the fixed components and the radiator and the components on the board?

5: Welding design specification for circuit board design
A: Whether there is a 3mm wide reserved bracket position in the middle of the PCB board that is wider than 180mm or longer than 320mm through wave soldering
B: The reserved position of the support bar should not be within the bending range of the component lead
C: Components that are not suitable for wave soldering due to structural limitations, need to add a tin bath at the opposite position to the wave crest, and the slot width is 0.7mm
D: The direction of wave soldering needs to be clearly marked on the upper and lower sides of the board
E: Try not to lay out components like horizontal plug-in wires that extend out of the edge of the board.
F: The bend of the lead of the electrical plug component, the area around the triode, IC and the socket pin pads, should be coated with a secondary solder mask
G: A large area of copper foil is easy to be heated to produce copper foil expansion, so the area exceeds the diameter of the 15mm circle, the conductive layer needs to open a conductive window or grid