LED display panel PCB design rules

Time:2018-10-22 Views:228

1, general
(1) if the design rules are satisfied, the production cost should be reduced as much as possible.When costs and design rules conflict, design rules are guaranteed.
(2) the components are arranged neatly, and the same chip is arranged in rows according to certain rules;The spacing of components and components should be considered in production process and should not affect welding.
(3) for PCB design, automatic wiring is not allowed.
2, the detailed rules for the
(1) use of wiring layer
When designing the circuit board more than 2 layers, the inner electric layer is prohibited.Use the inner layer definition as normal.
For the cell plate that needs to be designed with blind hole, for the four-layer plate, 1-2,3-4,1-4 punching;For six-ply plates, holes are 1-2,2-5,5-6.The specific process shall be confirmed with PCB manufacturer after confirmation.
(2) separate power supply for digital devices and drive devices
To use the digital and analog separate wiring method, the digital part of the power supply is only at the entrance of the power base through jumper wire and the power supply of the driving part.
With space on the board, it is recommended to separate the column - driven power supply from the line - driven power supply.
(3) power cord and line:
Power supply main line width of digital part >=50mil.
The width of power cord and line should take the current, width and distance of power branch into consideration.Ensure the online pressure drop from power inlet to module is not greater than 0.01v.
It is recommended that the power base be placed in the middle of the board.When the power base is positioned to one side, reserve the power base or welding plate on the symmetrical side to facilitate the production of flying wire.
When the wiring is difficult, the power welding panel is reserved on the board to facilitate the production of flying wire.
The circuit board where the line drive is located shall have a separate power base or solder pad.
The circuit board where the column drive is located shall have a separate power base or solder pad.
When power supply and line connection is made by non-welding method (pin, hole and cable), the current of each pin is not greater than 1A, and there are at least two pins for each connection.
For user already have lamp board to discuss separately.
It is recommended that the line pipe be placed in the middle of the line within 1/3 of the entire cell floor.
For outdoor screen, lamp board drive board separated, line pipe should be placed at the closest place to lead pin.
(4) requirements for ground line
The trunk width of the digital part is >=50mil.
The ground wire of the column drive part should be wider than the line drive power line and is recommended to be more than 1.5 times the width of the power line.
The flooring of the unit board shall be arranged in a checkerboard pattern, and the branches shall be connected with each other.
The driving part is covered with copper, and the digital part with grid.The distance between ground and other parts is set above 20mil.The grid ground has a line width of 25mil and a center spacing of 40mil.
When laying the ground, avoid the blind corner.After laying, the parts will be separated and connected by manual laying.
Put the test pin at the power inlet on a simulated basis.
Digitally place test pins between input pins, output pins, and 9702.
(5) capacitance requirements
Put 100u electrolytic capacitance and 104 capacitors in the power inlet of the drive and digital parts.
Place 100u electrolytic capacitance at the inlet and end of the power line branch.
The position of 100u electrolytic capacitance near the line drive chip is recommended.
The position of 104 capacitance between the power supply pin and the ground of the drive chip in tandem.
(6) output of chip power pin
The power pin of the line drive chip shall be at least as wide as the pad.
(7) alignment and signal line:
Outdoor panel, line and signal line width >=12mil.When the PCB size is large, it is recommended that the signal line width is 15mil.
On other occasions it is recommended that the width of the line and signal line be 12mil, at least 10mil.
Line spacing should not be less than minimum line width.
(8) via hole:
Lamp panel for outdoor screen, pass parameter 50 mil, 28 mil.
In other cases, it is suggested that the bores parameter is 50 mil and 28 mil.At least 40 mil, 24mil.
The spacing between holes and lines should not be less than the minimum line width.
The outside diameter of the power supply main pipe is < the power line width, and the inner diameter of the power supply main pipe is >= the power line width *1/3.Recommended bore inner diameter: 28mil, 40mil.
Large power supply and ground wire can increase the number of through-holes.
To ensure welding, do not put the hole on the pad.At least 5mil from pad.
(9) plug welding device
The through hole of the solder pad of the plug - in device should be guaranteed.
Ordinary pinhole inner diameter 40mil, power socket pad hole 60mil.

(10) mounting hole:

For the unit plate using LED module, the mounting hole should not be located at the junction of the two modules. Copper foil should not be around the hole to prevent the mounting hole from being connected to the dc of the unit plate (the customer‘s signature is required as a last resort).

General components should be placed 3.5mm away from the fixed hole center, and relatively high components (such as capacitors, plug-in chips) should be placed more than 5mm away from the fixed hole center.

In case the user does not specify the requirements, the stage connecting pin and power base shall be placed 2cm away from the horizontal and vertical connection of the fixed hole.

When designing a PCB for a specific customer, specify the customer‘s fixed hole location and fixed structure to determine the placement of pins, power bases, and other devices.

(11) modules

Module boundaries can not be inserted welding components.

The module recommends "queue placement" or grid placement to avoid errors.

The PCB edge should be at least 20mil smaller than the module.

The modules are built according to the front view, and positioned on the back side, so that the front solder pad of other devices is not covered by the screen printing at the edge of the module.

The center distance of module placement should be point spacing *8.When the module accuracy is too low to guarantee the data, the center distance of the module should be placed with the customer.

(12) optimization:

After the layout design is completed, it should be reviewed and optimized.

Should increase the power line width, as far as possible ground wire into a checkerboard.

(13) order of cloth board: before the cloth board, it shall conduct pre-wiring, adjust the routing of the column line, and return to modify the schematic diagram and network table to make the routing of the column line the most convenient.When cloth board, want to arrange line first, power line and ground line, level connect signal line, next is other line.

(14) after the PCB design is completed, there should be the PCB processing process requirements for the unit board, including: PCB version thickness requirements, PCB version copper foil thickness requirements, PCB version minimum wire width, PCB version minimum spacing, and PCB minimum through-hole parameters.Convenient to select board manufacturers in the process of board casting.

(15) after the PCB design is completed, the component list should be made to clearly mark all kinds of component packaging. If there are reserved locations, the parts that are not welded during production should be specially indicated.The component list should also include a simple welding instructions.

(16) screen printing layer

After the design is completed, the information of the board is marked on the TOP layer of the board, including the board number, basic parameters of the board, and completion date.

The prominent position of the unit plate at the level connection entrance and level connection exit should be marked with obvious level connection direction;There should be a clear indication of the position of the 1 foot of the stepper and other stepper pins;There should be an easy to observe +- sign next to the positive and negative pins of the power base, and there should be a clear indication of welding direction;For empty solder pads designed for jumpers, obvious network names should be placed;For the unit board separated from the drive board, there should be obvious direction indication on both the lamp board and the drive board, or asymmetrical treatment at design time.

For the component dividing the positive and negative poles, the layout should show the direction of the positive and negative poles.For example, diodes, voltage stabilizers, electrolytic capacitors, power sockets, etc., shall not be covered after the welding of the direction mark.

For the unit board of virtual pixels, in addition to the welding direction of the led, there should also be a clear R/G/B sign. For the unit board that cannot be used as bottom screen printing of the led lamp attached to the table, the arrangement of led lights should be specified in the production specification.

In order not to affect welding, the characters of the screen layer can not overlap with the pad.

When the drawing is completed, place the name of IC under IC.For 62706 or 595, place the label of control color next to the IC;

After the PCB design is completed, an optical registration point is placed on the diagonal of the PCB.

(17) detection

DRC test shall be carried out when the design is completed.DRC testing is also performed when PROTEL99 and POWERPCB are converted to PROTEL2.8.

When you use PowerPCB to draw and import into the Protel2.8 format, it‘s important to note that sometimes the holes on the board change size.After drawing the diagram with the Protel99 software, when imported into the Protel2.8 format, the vertical placement FILL may be changed to horizontal placement.These are the things you need to pay attention to in drawing.

When drawing PCB, it is necessary to show the direction of positive and negative pole on the map for the component dividing positive and negative pole.Such as diodes, voltage stabilizing tube, electrolytic capacitance, power base, etc.

For biped components, the library of SIP2 or IDC2 common 2-pin components must not be used, and the special library must be used.

For power base or power pad, be sure to mark the network name (or positive and negative sign) on the screen.

For single and double row needles, there should be a clear mark on the position of one foot.

For other components, there must be a clearly marked 1 pin mark or a welding direction mark.

For unconventional USES, be sure to include them in the production instructions.

For the unit board of virtual pixels, in addition to the LED welding direction, there should also be a clear R/G/B mark. For the unit board that is attached to the table and cannot be used as bottom screen printing, detailed explanation should be given in the production specification.