Rigid Flex PCB is a combination of soft board and hard board. It is a circuit board formed by combining thin flexible bottom layer with rigid bottom layer, and then laminating into a single component.
When selecting high frequency materials for high power RF applications, the materials should have low Df, relatively smooth copper foil, high thermal conductivity and low TCDk.There are a number of trade-offs involved when considering the properties of these materials and the end-use requirements.Therefore, when selecting materials for high-power RF applications, designers are always wise to contact their material suppliers.
With the rapid development of THE PCB industry, PCB gradually develops towards the trend of high precision fine lines and small aperture. Generally, PCB manufacturers have the problem of electroplating clip film. The PCB clip film will cause direct short circuit, which will affect the primary yield of PCB board through AOI inspection, and the serious clip film or too many points cannot be repaired directly leading to scrap.
1. The anti-plating film layer is too thin, and the coating exceeds the film thickness during electroplating, forming PCB clip film, especially the shorter the line spacing is, the easier the clip film short circuit will be caused.
2, the graphic distribution of the plate is not uniform, isolated several lines in the graphic plating process, due to high potential, coating beyond the thickness of the film, resulting in the formation of clip film short circuit.
1, increase the thickness of the coating
Select the appropriate thickness of the dry film, if it is wet film can be printed with a low mesh screen, or by printing twice wet film to increase the film thickness.
2. The plate is not uniformly distributed, and the current density (1.0~ 1.5a) should be appropriately reduced for electroplating
In daily production, we out of reasons to ensure the production, so the control of the electroplating time is generally shorter, the better, so using the current density is between 1.7 ~ 2.4 A commonly, so get of current density on isolated area will be 1.5 ~ 3.0 times of normal area, often causing isolated area on the place of small spacing coating over many film thickness, high back membrane membrane is not net, back after serious appears the phenomenon of line edge clamped resistant coating, short-circuit, resulting in the capsule also makes partial thin line of resistance welding on the thickness.
Multilayer PCB board is a printed circuit board composed of alternating conductive graphic layer and insulating material laminated.There are more than three layers in the conductive pattern, and the electrical interconnection between the layers is realized through metallized holes.If using a double panel as inner lining, two pieces of single panel as the outer layer or two pieces of double panel do lining, two pieces of a single panel as the outer layer, through the positioning system and insulation bonding material overlying together, and the conductive graphics interconnection, according to the design requirements become four, six layer printed circuit board, also known as multilayer PCB circuit board.
Common quality problems in SMT chip processing
I. Common causes of missing parts in SMT patch processing
1. The suction nozzle airway of the component is blocked, the suction nozzle is damaged, and the suction nozzle height is incorrect;
2. The real air path of SMT equipment is broken and blocked;
3. Circuit board inventory is insufficient and deformation is serious;
4. There is no or too little solder paste on the solder plate of circuit board;
5. The quality of parts is not consistent with the thickness of the same type;
6. Errors and omissions exist in SMT callers used in SMT machining, or errors exist in the selection of component thickness parameters in programming;
7. Human factors are inadvertently touched.
Ii. Common reasons for SMT patch processing side parts and turning over parts
1. The mounting head suction nozzle height is not correct;
2. The mounting head of the placement machine has the wrong scratch height;
3. The charging hole size of the component woven is too large, and the component is overturned due to vibration;
4. When weaving, the bulk material is in the opposite direction.
Iii. Common causes of SMT chip processing element deviation
1. When SMT is programmed, the x-y axis coordinates of components are not correct;
2. The existence of patch suction nozzle makes the suction nozzle unstable.
Common causes of COMPONENT loss in SMT SMT processing
1. The positioning pin is too high, resulting in too high circuit board position, extrusion elements during installation;
2. When SMT is programmed, the z-axis coordinate of the component is incorrect;
3. Suction spring of SMT placement machine mounting head is stuck.
Solutions to common quality problems in SMT chip processing
1. Selection of technical personnel: The establishment of a total quality organization network within the enterprise to provide timely and accurate quality feedback and select the best talent as the quality inspector of the production line, in the management is still under the management of the quality department, in order to avoid other factors interfering with the quality of determination.
2. Ensure the accuracy of testing and maintenance equipment: Test and repair products with necessary equipment and instruments such as multimeter, anti-static carpal pipe, soldering iron, ICT, etc.
3. Setting of quality process control points: In order to ensure the normal processing of SMT, it is necessary to strengthen the quality inspection of each process to monitor its running status.
4. Formulate quality rules and regulations: The quality Department formulates necessary regulations and the department’s work quality responsibility system to avoid quality accidents through regulatory restrictions, with clear rewards and penalties, participate in quality evaluation through economic means, and establish a monthly quality award within the enterprise.
5. Implement management measures: in addition to strictly controlling the quality of the production process, SMT SMT processing quality management also takes measures to record the inspection results.
In daily life, multi-layer PCB is currently the most used type of PCB, can have such an important proportion, must benefit from the many advantages of multi-layer PCB, the following to see what advantages.
Application advantages of multi-layer PCB board:
1. High assembly density, small volume and light weight meet the requirements of light and miniaturization of electronic equipment;
2. Due to the high assembly density, the connection between each component (including components) is reduced, with simple installation and high reliability;
3. Due to the repeatability and consistency of the graphics, the wiring and assembly errors are reduced and the maintenance, debugging and inspection time of the equipment is saved;
4. The number of wiring layers can be increased, thus increasing the design flexibility;
5, can form a certain impedance circuit, can form a high-speed transmission circuit;
6. Circuit and magnetic circuit shielding layer can be set, and metal core heat dissipation layer can be set to meet the needs of special functions such as shielding and heat dissipation.
With the continuous development of electronic technology and computer, medical, aviation and other industries on the continuous improvement of electronic equipment requirements, circuit boards are shrinking in volume, reducing in quality and increasing in density.Due to the limitation of available space, it is impossible to further improve the assembly density of single and double-sided printed boards. Therefore, multi-layer circuit boards with more layers and higher assembly density need to be considered.Multi-layer circuit board with its flexible design, stable and reliable electrical performance and superior economic performance, has been widely used in the production of electronic products.