What does PCB panel mean
In the PCB production and assembly process, some PCB boards are too small, which are irregular shape or do not meet the requirements of making fixtures , PCB manufacturers use PCB panels to put the circuit boards together and process in order to save costs and improve production efficiency. Commonly used panel connection methods are v-cut, stamp hole and hollow connecting strips.
What are the types of PCB panel
In the design process, we need to put the panels together After the processing is completed, we need to add boards for separation, which involves our panel division method, there are three conventions:
V-CUT
Printed circuit board (PCB) manufacturers cut the dividing line in advance in the specific position of the PCB with the turntable tool, according to the customer’s drawing requirements, whose purpose is to facilitate the subsequent SMT circuit board assembly after the completion of the De-panel use. Because its cut appearance looks like an English [V] shape, hence the name.
Features: V-cut is suitable for PCB with straight side, such as rectangular PCB. At present, SMT plate is widely used, characterized by neat edges after separation, low processing cost, it is recommended to prefer.
Hollow connecting strips
When splicing circuit boards surrounded by half-holes, they can only be connected at four corners through hollow connection strips. The connection part of the connection strip is a little narrower than the other two methods, and there are no vias on either side. Then through a small circuit board directly connected, this kind of board division needs to use the board machine, manual can not be separated.
Features: No burrs and unevenness, need to use the board splitting machine The cost will increase.
Stamp hole
The way of stamp hole is to connect the edges of the two boards through a small plate, and there are many small holes in the connection between this small plate and the two plates, which is easy to break. It is called a stamp hole because the edge of the board after breaking resembles the edge of a stamp. Generally, the PCB adopts V-CUT, and stamp holes may be used if it encounters special-shaped or round plates.
Features: suitable for special-shaped plates, wide range of application, the disadvantage is burrs, not neat.
How to make a PCB panel
Take stamp hole imposition as example, the process is mainly divided into 3 steps:
Step 1: Design the stamp hole;
Step 2: Design the number of PCB;
Step 3: Design the process edge.
2.1. Design stamp holes
Generally, the key points of stamp hole design are as follows:
The spacing (center distance) between two adjacent vias in the same row is 1mm, and the distance between the two rows of vias is 2mm;
Stamp holes: 8 holes of 0.55mm, hole spacing: 0.2mm, hole center distance: 0.75mm;
The stamp hole extends to 1/3 position inside the board;
After adding the stamp hole, the shape on both sides of the hole is connected with forbidden wiring, which is convenient for the production of the gong belt after work.
2.2. Design the number of PCB
If you want to design a PCB board with 4 finished units, you need to copy the above PCB board with stamp holes.
Use the shortcut keys: Ctrl+A selects all PCBs, Ctrl+C copies PCBs.
Use Special Paste to copy the PCB to the newly created PCB file for imposition, ensuring that the source file is not affected.
2.3. Design process edge
What is the process side? the process side is to add 5mm on each side of the PCB board, and there can be no SMD components on these two sides.
The process side of the PCB board is used for SMT machine mounting. For factories, it is more cost-effective to add no process, but large-scale production must use machines, and production with machines must meet certain standards.
Finally, it is necessary to add MARK points and positioning holes to the designed process edge, which are position identification points, also known as reference points, on the automatic placement machine used by the PCB in the design.
How to reduce the cost of PCB panel
1. Panel and process side design, no need to open fixtures
1) Is it faster to paste 1pcs at a time, or 6pcs faster at one time? Panels improve productivity and mean faster delivery; Faster delivery means less time to market, giving competitors a greater advantage.
2) With the panel and process side design, there is no need to open the fixture, and the lack of fixture saves the prenatal preparation time, so that it can give faster delivery;
2. The PCB panel method is suitable, saving board materials and saving costs
There are many designed boards that are special-shaped, and factory boards are calculated in terms of length and width, which means that it is likely that many of the boards of the PCB you design have become unusable scrap. The use of panels can greatly avoid waste.
As shown in the figure below, the cost of two ways is very different.
3. Multiple projects are combined to save costs
If there are many projects and the cost is limited, and the number of layers and production and processing technology are consistent, then multiple boards can be combined and designed into one, although the board factory will charge a certain assembly fee, but it is definitely much cheaper than multiple projects to process separately. And if multiple projects are made into a BOM Normally, the patch factory is done according to one project, so that the cost of patch is greatly saved.
What are the rules and methods of PCB panel
1, according to different SMT factory process requirements, the maximum size and minimum size of the panel should be clear, generally speaking, less than 80X80mm PCB needs panel, the maximum size should be determined according to the processing capacity of the factory; In short, the PCB panel size should meet the equipment size requirements of the SMT patch processing production line, which is conducive to SMT patch processing, and determine the panel size according to the PCB board thickness.
2. The panel sub-board should meet the requirements of DFM DFA, and at the same time ensure that the PCB panel is fixed and not easy to deform after the fixture. The split groove between the panels should meet the flatness requirements of the surface during PCBA patch processing.
3, In the PCB panel design, the arrangement of components to avoid the division stress and cause component fracture, the use of pre-engraved line of the panel structure form can minimize the warpage deformation when dividing the board, so that the stress of the components is minimized, try not to lay out valuable components next to the process side.
4, The size and form of the panel according to the specific project processing, the appearance design as close as possible to the square, it is strongly recommended to choose 2×2, 3×3 panel method, it is not recommended to put together the yin and yang board if it is not necessary;
5. When the outline of the board edge connector between the multi-panel boards exceeds the interference, it is solved by rotating the splicing + process edge to prevent the poor quality of the collision damage during transmission or handling after welding.
6, after the design of the panel, it must be ensured that the edge of the reference point of the large board is at least 3.5mm from the edge of the board (the minimum range of the machine in clamping the PCB board edge is 3.5mm), the two diagonal reference points on the large board cannot be placed symmetrically, and the reference points on the front and back sides should not be placed symmetrically, so that the foolproof PCB reverse/reverse side can enter the machine through the identification function of the equipment itself.
7, when the thickness of the PCB board is less than 1.0mm, plus the panel connection bit or V-cut groove, the strength of the entire panel board will be greatly reduced (weakened), because the V cutting depth is 1/3 of the thickness of the board, the PCB board in the middle of the strength, the supported skeleton —- glass fiber cloth V is partially broken, resulting in significantly softening of strength, if not supported by fixtures, it will affect the process below the PCBA.
8. When there is a gold finger on the PCB, generally put the gold finger in the direction of the non-splint position on the outside of the board edge. The gold finger edge cannot be joined by panels or added to the process edge.
Consideration about size of PCB panel
●The length is greater than the width. The maximum production imposition size is generally 20X16Inch.
● PCB panel shape as close as possible to square, recommended 2×2, 3×3、…… panels.
●PCB panel width≤ 260mm(SIEMENS line) or ≤300mm (FUJI line); If automatic dispensing is required, PCB panel width × length ≤ 125mm ×180mm.
●Each small board in the PCB panel must have at least three positioning holes, 3≤ hole diameter ≤ 6 mm, and no wiring or patch is allowed within 1mm of the edge positioning hole.
●The center distance between the small plates is controlled between 75mm~145mm.
●When setting a mark, leave a solder-free area 1.5mm around the mark.