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Smt process for pcb
Basic science
What's the smt process
I. Premises
There's already a pcb sample
️ there are well-equipped meta-wares that need to be installed (how many units are required because the process will be depleted, with a loss rate of about three parts per thousand)
The processing requirements have stated that bom is correct, consistent with the equipment used, and has the necessary instructions to prevent the procurement of the equipment from failing and causing loss
• leave sufficient processing time to prevent delivery on time (usually one week for a shipment to be processed)
When you draw the pcb, you can't change the originals, you can't change the plates, or else there's a problem with the location of the steel grid
Iii. Introduction to the use of machines
The dip can only be welded manually
Iv. Smt basic processes
1. Printing of tin ointment
In normal cases, tin ointment is stored in a freezer room, which is to be released 12-24 hours before use to free itself from freezing
The steel network is 550 ~ 650 mm in size and is too small to print
Spi: detection of cassiterite short circuits, leaks, tin, offset, thickness, volume, area
Each pcb is self-censored, and printing of tin ointment does not allow for adverse phenomena such as polytin, tin, tin, and oscillation. The printing of bad material is carefully cleaned. Clean steel nets in time. Add cassiterite in time to ensure that it scrolls on the steel network。
Equipment used: full autoprinter, 3-vv tin ointment detection equipment (spi)
2. Parts and components
Poster order: small, low, large, high
For small pieces, only one sticker is required, while large pieces are required to occupy two to three stickers, which may also affect the efficiency of the sticker plant, which, according to the established procedures, rank the pieces and form a material statement (including material models, requirements, postings, etc.), which forms a sample seal and is recorded。
Use of equipment: multifunctional patches
Three, back welding
Reveal furnaces are generally 10 hot zones, with a better quality of 12. It is divided into preheating areas, hot zones, welding areas, cooling areas, and the more hot areas represent the temperature increase rate. The temperature of the furnace will be slightly below the set temperature. Pcb maximum width: 450 mm。
The temperature requirements of the core metaware need to be checked and requested to the processing plant
Use of equipment: reveal furnace (computer display and control temperature)
4, aoi optical test
Aoi (auto optical test)
Automatically use optical online tests to detect the negative range of welded plates: faults, leaks, reverses, multiple pieces, reverses, deviations, tins, dosage, empty welds, tin beads, sidestips, deviating feet, foreign objects。
Use of equipment: fully automated optical detectors
5, x-ray test
The principles for detection of x-ray equipment are basically x-ray projectors. Under high voltage power, x-ray transmitters produce x-rays to produce images on image receivers by testing samples (e. G. Pcb plates, smts, etc.), depending on the density of the sample material itself and the amount of atoms, and x-rays are also subject to different absorptions. The detection of x-ray equipment has been widely used in the bga detection, led, smt, semiconductor, electronic network module detection, containment components, aluminium-pressed casts, plastic mould components, ceramics, electrical and mechanical components, automated components, agriculture (seed detection) 3d printing analysis, etc. In processing plants, such as qfn seals, the bottom of the welding is not visible and can only be seen through x-ray equipment。
Usage equipment: x- whatRay tester
6. Inspection
A simple look check is performed, and if functional tests are required, test documents and requirements are provided。
7. Supporting tools 7. 1 brewery
Welding, which is used with plugins and stickers, is used to keep the material from being taken while passing through the furnace. The area where the device is available is empty and needs to be inserted directly into the welded area and exposed。
7. 2 tunnels
Sorrow in the plate surface
7. 3 high temperature aging shelf
The ageing cycle is determined by the needs of the client, and the high temperature aging experiment is a simulation of a high temperature, bad environmental test for high performance electronics (e. G. Computer completes, vehicle electronics, power supply, mainframe boards, monitors, etc.)。
7. 4 test platform
7. 5 test racks
It is provided by the client on its own basis to facilitate the testing of its pcb
7. 6 test panel function
7. 7 burning program testing of boards
V. Other
Advantages of smt paste processing: high assembly density, small size and light weight of electronic products, only about 1/10 of traditional plug-in components in size and weight in size of packaged components, generally reduced by 40 per cent 60 per cent in volume and 60 per cent in weight of electronic products. High reliability and resilience. Weld defects are low. Hf is good. There is less electromagnetic and radio frequency interference. Automation is easy and production efficiency is improved. The cost reduction is 30% - 50%. Savings in materials, energy, equipment, manpower, time, etc。
The function and the structure of the bough
