With the development of electronic products to high density and high precision, the same requirements are put forward to the circuit board. The most effective way to improve PCB density is to reduce the number of through holes, and precisely set up blind holes, buried holes to achieve.
Knowledge of blind orifice fabrication of circuit board
A: In contrast to through hole, through hole refers to the hole drilled through all layers, while blind hole is non-drilled through hole. Eight layer board (graphic illustration, for example: HOLE, BLIND HOLE, HOLE BURIED) B: BLIND HOLE segmentation: BLIND HOLE, BLIND HOLE), BURIED HOLE BURIED HOLE (outer not see); C: From the production process: the blind hole is drilled before pressing, while the through hole is drilled after pressing.
A: Drill belt:
(1) : select reference point: select through hole (that is, a hole in the first drilling belt) as the unit reference hole.
(2) : A hole shall be selected for each blind hole drilling belt, and its coordinate relative to the unit reference hole shall be marked.
(3) : Note which drill belt corresponds to which layers: the unit hole diagram and drill tip table should be indicated, and the name of the front and back should be consistent; It is not possible to use A, B and C to represent the hole plot, and then use 1st, 2nd to represent the hole plot.
Note that when the laser hole is sheeted together with the buried hole in the inner layer, that is, the holes of the two drill belts are in the same position, it is necessary to move the laser hole to ensure the electrical connection.
B: Production PNL plate edge process hole:
Common multilayer board: the inner layer is not drilled;
(1) : Rivet GH, AOI GH, ET GH are etched after hitting (beer out)
(2) : Target hole (drilling GH) CCD: the outer layer should be cut copper, X-Ray machine: directly punched, and note that the long side is minimum 11inch.
Blind hole plate: All tooling holes were drilled out, note the rivet GH; It should be brewed out to avoid counterpoint deviation. (AOI GH is also for beer), the production of PNL plate edge need to drill words, to distinguish each board.
(1) : indicate the positive film, negative film:
General principles: the thickness of the plate is greater than 8mil (without copper) through the positive film process; The thickness of the plate is less than 8mil (without copper) through the negative process (thin plate); The copper thickness at D/F, rather than the copper thickness at the bottom, should be considered when the line thickness and the gap valley are large. 5mil for blind hole ring can be done, and 7mil is not needed. The inner layer of independent pad corresponding to the blind hole should be retained. Blind hole can not be made without ring hole.
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