PCB process requirements and notes
In the PCB copy board, PCB design, and finally the mass production of PCB, PCB board is also a very important thing, which not only involves the quality standards of PCB circuit board, but also affects the cost of PCB production.
How to save the raw materials under the premise of ensuring the quality of the PCB circuit board is a problem that the PCB copy board company and the PCB production company pay great attention to.
PCB assembly process requirements:
For irregular graphic panels, there will be gaps and there will be no hollowing out on both sides of the panel. (At least one side will not be hollowed out.) Otherwise, the positioning hammer of the SMT machine cannot be positioned and the patch cannot be patched. Please pay attention to the PCB assembly process requirements. Pay attention to pad via metallization (PHT) and non-metallization (NPTH) for dual panels.
The main contents of the PCB panel specifications and standards:
PCB panel width ≤ 260mm (SIEMENS line) or ≤ 300mm (FUJI line); if automatic dispensing is required, PCB panel width × length ≤ 125 mm × 180 mm
The shape of the PCB is as close as possible to the square. It is recommended to use 2×2, 3×3, ... jigsaw; but do not spell the yin and yang
The outer frame (clamping edge) of the PCB panel should adopt a closed loop design to ensure that the PCB panel will not be deformed after it is fixed on the fixture.
The center distance between the small plates is controlled between 75 mm and 145 mm
There should be no large devices or protruding devices near the connection point between the outer frame of the panel and the inner small plate, small plate and small plate, and the space between the components and the PCB should be more than 0.5mm to ensure Cutting tool is running normally
Four positioning holes are opened at the four corners of the outer frame of the panel, the hole diameter is 4mm±0.01mm; the strength of the hole should be moderate to ensure that it will not break during the upper and lower plates; the aperture and position accuracy are high, the hole wall is smooth and burr-free
Each small plate in the PCB panel must have at least three positioning holes, 3≤ aperture ≤6 mm, no wiring or patch is allowed within 1mm of the edge positioning hole
The whole board positioning for the PCB and the reference symbols for fine-pitch device positioning, in principle, the QFP with a pitch less than 0.5mm should be set at its diagonal position; the positioning reference symbols for the imposition PCB sub-board should be used in pairs, arranged At the opposite corner of the positioning feature.
When setting the reference positioning point, usually leave a non-resistive soldering area 1.5 mm larger than the positioning point.
Large components should have positioning posts or positioning holes, such as I / O interface, microphone, battery interface, micro switch, headphone interface, motor and so on.
PCB board other notes:
1. Pay attention to the edges and slots when the PCB is in the panel.
The edge is reserved for the later soldering of the plug-in or the patch. The slot is to separate the PCB. The process requirements for leaving the edge are generally 2-4MM, and the components should be placed on the PCB according to the maximum width. Slotting is to prohibit the wiring layer, or the material layer, which is specifically agreed with the PCB manufacturer for processing and processing, and the designer can mark it. PCB jigsaw is designed to facilitate production and improve work efficiency. You can choose it yourself.
2. V-grooves and slots are a way of milling the outer shape.
It is easy to separate multiple boards during the imposition to avoid damage to the board during separation. Depending on the shape of the single variety you are splicing to determine which method to use, v-cut needs to go straight and is not suitable for four boards of different sizes.
1. Generally, there are no more than 4 kinds. The number of layers, copper thickness and surface process requirements of each board are the same. In addition, negotiate with the manufacturer's engineers to achieve the most reasonable imposition plan.
2, the puzzle is to save costs, if the production process is more complicated, the bulk is recommended to be produced separately, the board must also bear the scrap rate of 10%-20%.