Due to the complex process flow of PCB manufacturing, in the planning and construction of intelligent manufacturing, it is necessary to consider the related work of process and management, and then carry out automation, information and intelligent layout.
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Process classification
According to the number of PCB layers, it is divided into single-sided, double-sided, and multi-layer boards. The three board processes are not the same.
There is no inner layer process for single-sided and double-sided panels, basically cutting-drilling-subsequent processes.
Multilayer boards will have internal processes
1) Single panel process flow
Cutting, grinding, drilling, outer graphics (full board gold plating), etching inspection, screen printing solder mask (hot air leveling), screen printing character shape processing test and inspection
2) Process flow of double-sided tin spraying board
Cutting material, edging, drilling, sinking copper, thickening of the outer layer graphics, tinning, etching and de-tinning, secondary drilling inspection, screen printing, solder mask, gold-plated plug, hot air leveling, screen printing character shape processing test and inspection
3) Double-sided nickel-gold plating process
Cutting, grinding, drilling, sinking, copper, thickening, outer layer graphics, nickel plating, gold, removing film, etching, secondary drilling inspection, screen printing, solder mask, screen printing, character shape processing, testing and inspection
4) Multi-layer board tin spraying process flow
Cutting edge drill positioning hole, inner pattern, inner layer etching inspection, blackening laminated drilling, sinking copper thickening outer pattern, tinning, etching and detinning, secondary drilling inspection, screen printing, solder mask, gold-plated plug, hot air leveling, screen printing character shape processing Test inspection
5) Process flow of nickel-gold plating on multilayer boards
Cutting edge drill positioning hole, inner layer pattern, inner layer etching inspection, blackened lamination drilling, sinking copper thickened outer pattern, gold plating, film removal etching, secondary drilling inspection, screen printing, solder mask, screen printing character shape processing test and inspection
6) Process flow of multilayer nickel-gold plate
Cutting edge drill positioning hole, inner layer pattern, inner layer etching inspection, blackened laminate drilling, sinking copper thickening outer layer pattern, tinning, etching and de-tinning, secondary drilling inspection, screen printing, solder mask, chemical sinking, nickel, gold, screen printing, character shape processing test test
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Inner layer production (graphic transfer)
Inner layer: cutting board, inner layer pre-processing, lamination, exposure, DES connection
Cutting (Board Cut)
1) Cutting board
Purpose: Cut the large material into the size specified by MI according to the requirements of the order (cut the substrate material to the size required by the work according to the planning requirements of the pre-production design)
Main raw materials: base plate, saw blade
The substrate is made of copper sheet and insulating laminate. There are different thickness specifications according to the requirements. According to the copper thickness, it can be divided into H/H, 1OZ/1OZ, 2OZ/2OZ, etc.
Precautions:
a. To avoid the impact of the board edge barry on the quality, after cutting, the edges are polished and the corners are rounded.
b. Considering the impact of expansion and contraction, the cutting board is baked before being sent to the process
c. Cutting must pay attention to the principle of consistent mechanical direction
Edging/rounding: mechanical polishing is used to remove the glass fibers left by the right angles of the four sides of the board during cutting, so as to reduce scratches/scratches on the board surface in the subsequent production process, which may cause quality hazards
Baking plate: remove water vapor and organic volatiles by baking, release internal stress, promote cross-linking reaction, and increase the dimensional stability, chemical stability and mechanical strength of the plate
Control points:
Sheet material: puzzle size, sheet thickness, sheet type, copper thickness
Operation: baking time/temperature, stacking height
(2) Inner layer production after cutting board
Function and principle:
The inner copper plate roughened by the grinding plate is dried by the grinding plate, and the dry film IW is attached, and then irradiated with UV light (ultraviolet rays). The exposed dry film becomes hard and cannot be dissolved in weak alkali, but can be dissolved in strong alkali. The unexposed part can be dissolved when exposed to weak alkali, and the inner layer circuit uses the characteristics of the material to transfer the graphics to the copper surface, that is, image transfer.
Detail :(The photosensitive initiator in the resist in the exposed area absorbs photons and decomposes into free radicals. The free radicals initiate a cross-linking reaction of the monomers to form a spatial network macromolecular structure that is insoluble in dilute alkali. It is soluble in dilute alkali after reaction.
Use the two to have different solubility properties in the same solution to transfer the pattern designed on the negative to the substrate to complete the image transfer).
The circuit pattern requires high temperature and humidity conditions, generally requiring a temperature of 22+/-3℃ and a humidity of 55+/-10% to prevent the film from deforming. The dust in the air is required to be high. As the line density increases and the line becomes smaller, the dust content is less than or equal to 10,000 or more.