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PCB Tech

PCB Tech - What are the skills and methods of PCB drawing

PCB Tech

PCB Tech - What are the skills and methods of PCB drawing

What are the skills and methods of PCB drawing

2021-10-25
View:399
Author:Downs

When using ERC for PCB drawing, a "Multiple Net Identifiers" error message appears:

Solution: It may be because different network labels are connected together, or different network labels are given to the same cable.

If it is a single schematic diagram, you can find the position with the error label on the diagram; if it is multiple schematic diagrams, search all the diagrams; especially when it is a multi-layer schematic diagram, the error is likely to be in the sub-diagram.

1. Common errors in schematic diagrams:

(1) There is no signal connected to the ERC report pin.

b. Inconsistent grid attributes were modified when components were built or placed, and the pins and wires were not connected.

c. When building the component, the pin direction is reversed, and the non-pin name terminal must be connected.

(2) ERC reports duplicate network identifiers (Error: Multiple Net Identifiers).

It may be because different network labels are connected together, or different network labels are given to the same wire. It should be noted that the error pointed out by PROTEL is not necessarily the real error, and may also be wrong on other schematics (if it is a hierarchical circuit diagram)

(3) The component went out of the drawing boundary: no component was created in the center of the diagram paper of the component library.

(4) The network table of the created project file can only be partially imported into the PCB: when the netlist is generated, global is not selected.

(5) When using multi-part components created by yourself a, never use annotate.

2. Common errors in PCB boards:

pcb board

(1) It is reported that NODE or FootPrint is not found when the network is loaded.

a. When loading the netlist, the corresponding PCB package library is not loaded in advance.

b. The components in the schematic diagram use packages that are not in the PCB library.

c. The components in the schematic diagram use packages with inconsistent names in the PCB library.

d. The components in the schematic diagram use packages with inconsistent pin numbers in the PCB library. For example, a triode: the pin number in sch is e, b, c, and the pin number in PCB is 1, 2, 3; diode: the pin number in sch is a, k, and the pin number is 1, 2 in PCB, just change it to the same.

(2) After importing components into the PCB, it is found that individual components are not within the range of the display, and the display scale of the drawing is reduced even if it is not visible. This is often due to the fact that the reference point is not set when the PCB component package is created. Generally, "set

reffrence" to "pin 1".

3. Copy the partial ProtelSch schematic and want to paste it into Word as follows (for protel 99, protel dxp should be analogous, not tried):

Tools-preferences-graphical editing: add template to clipboard option, just remove it.

4. About trace width

The default wiring of the system is 10mil. Generally, it can be set to 8mil. If it is thinner (for example, less than 6mil), ordinary small circuit board PCB manufacturers cannot make it. The cost of finding a large manufacturer will be high, and the specific situation will be measured. Note: 100mil (imperial system) = 2.54mm (metric system).