PCB News - PCB board process requirements and notes

In PCB copying, PCB design and PCB mass production, PCB assembly is also a very important thing, which not only involves the quality standard of PCB board, but also affects the cost of PCB production.

How to assemble boards reasonably and effectively under the premise of ensuring the quality of PCB boards, so as to save raw materials, is a problem that PCB copying companies and PCB production companies pay great attention to solve.

PCB board process requirements and notes

PCB board process requirements:

For irregular graphics, there will be gaps and then there shall be no hollowing at both corners of the panel (at least one side shall not be hollowed out). Otherwise, the positioning hammer of the SMT machine cannot be located and the patch cannot be made. Please pay attention to the process requirements of PCB panel, and the metalization (PHT) and nonmetalization (NPTH) must be paid attention to for the double panel.

Main contents of PCB board specification and standard:

PCB board width ≤260mm (SIEMENS line) or ≤300mm (FUJI line); If automatic dispensing is required, PCB board width x length ≤125 mm x 180 mm

PCB board shape as close as possible to square, recommended 2*2, 3*3...... Makeup; But don't make a Yin and Yang board

The outer frame (clamping edge) of PCB board should adopt closed-loop design to ensure that PCB board will not deform 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 device or outstretched device near the connection point between the outer frame and the inner small plate, and between the small plate and the small plate, and the edge of the components and the PCB board should be left with a space of more than 0.5mm to ensure the normal operation of the cutting tool

Four positioning holes are opened at the four corners of the outer frame of the board, with a diameter of 4mm±0.01mm;

The strength of the hole should be moderate to ensure that it will not fracture in the process of upper and lower plates; Aperture and position accuracy should be high, hole wall smooth without burr

Each small board in PCB board should have at least three positioning holes, 3≤ aperture ≤6 mm, edge positioning holes within 1mm are not allowed to wire or patch

In principle, QFP with a spacing less than 0.5mm should be set in the diagonal position of the reference symbol for PCB whole board positioning and for finely spaced devices positioning; Positioning datum symbols for PCB sub-boards should be used in pairs and arranged on the diagonal of positioning elements.

When setting a reference anchor point, it is usual to leave an open welding zone 1.5 mm larger around the anchor point

Large components should have positioning posts or holes, such as I/O port, microphone, battery port, micro switch, headphone port, motor, etc.

PCB board Other matters needing attention:

1. Pay attention to leaving edges and slotting when assembling PCB.

The edge is left in order to have a fixed place when welding plug-ins or patches later, and the slot is to separate the PCB board. The process requirements of the side are generally in 2-4mm, and the components should be placed on the PCB board according to the width. Slotting is in the forbidden wiring layer, or the material layer, the specific with PCB manufacturer agreed, processing, designers can mark. PCB board is to facilitate production, improve work efficiency, you can choose.

2. V-groove and slotting are a way of milling appearance.

It is easy to separate multiple boards to avoid damage to the boards during separation. Depending on the shape of the single type you are crafting, the V-cut needs to go straight and is not suitable for four boards of different sizes.

Puzzle requirements

1. Generally, there are no more than 4 kinds of plates. The layer number, copper thickness and surface process requirements of each plate are the same.

2. Jigsaw is to save cost. If the production process is complex and the batch is large, it is suggested to produce the jigsaw separately.