PCB News - PCB drilling process and process troubleshooting method

PCB drilling is a process of PCB plate making, but also a very important step. Mainly to the board drilling, wiring needs, to make a hole, structure needs, make a hole to do positioning; Multilayer PCB drilling is not finished, some holes buried in the circuit board, some get through on the board, so there will be a drill two drill. This paper first introduces the use of PCB drilling process, then describes the PCB drilling process and process manufacturing process capacity, introduces the PCB drilling process failure and solutions.

What is the use of PCB drilling process

Drilling is to connect the outer line and inner line, the outer circuit connected to the outer line, anyway, just for line connection between each layer and hole, the hole on the electroplating process behind the plating copper on the inside will be able to make the connection between each line, there are also some drilling is the screw holes, positioning hole, hole and so on, their purpose is not the same.

Drilling is to drill the desired hole through a copper clad plate. Through hole Through hole mainly provides electrical connection and serves as device fixation or positioning.

PCB through holes are divided into three parts according to whether they are metallized or not

1) Electroplated hole (PTH), also known as metallized hole

2) Non-electroplated hole NPTH) : also called nonmetallic hole

According to the process is divided into

1) Blind hole (multi-layer board)

2) Buried hole (multi-layer board)

PCB drilling process

1) Multi-layer drilling process

2) Double panel drilling process

PCB drilling process capability

1. Drill break

Causes are: excessive spindle deflection; Improper operation of NC drilling machine; Drill nozzle selection is not appropriate; The speed of the bit is insufficient and the feed rate is too large. Too many stacking layers; Panel and panel space or cover plate. Under the debris; When drilling the spindle depth is too deep resulting in the drilling nozzle chip discharge bad hanging; Too many grinding times of the drill nozzle or beyond the service life; The cover plate is scratched and wrinkled, and the backing plate is bent and uneven; When fixing the substrate, the tape is too wide or the aluminum sheet and plate of the cover plate are too small; Feeding speed is too fast to cause extrusion; Improper operation when filling holes; Serious ash blocking under aluminum plate of cover plate; The center of welding drill tip deviates from the center of drill handle.

Solutions:

(1) Notify machine repair to overhaul the spindle, or replace the good spindle.

(2) to detect the geometry of the drill nozzle, wear and choose the appropriate length of the chip slot drill nozzle.

(3) Select the appropriate feed quantity to reduce the feed rate.

(4) Reduce to an appropriate number of layers.

(5) Clean the sundries under the board surface and cover plate to keep the board surface clean.

(6) Inform the machine to adjust the drilling depth of the spindle and maintain a good drilling depth.(The depth of normal drilling holes should be controlled in 0.6 mm.)

(7) Control the grinding times (according to the operation instructions) or strictly according to the parameters in the parameter table.

(8) Select cover and pad with suitable and smooth surface hardness.

(9) Carefully check the state and width of the adhesive paper fixation, replace the aluminum sheet of the cover plate,and check the size of the plate.

(10) Properly reduce the feed rate.

(11) Pay attention to the correct hole position during operation.

(12) Replace the drill in the same center.

2. Hole damage

The reasons are as follows: take the drill nozzle after breaking the drill nozzle; No aluminum sheet or clamping back plate when drilling; Parameter error; The drill is elongated; The effective length of the drill head cannot meet the thickness of the Spanish board; Hand drilling; Special plate, batch front caused.

Solutions:

(1) According to the previous question 1, check the cause of broken knife and make correct treatment.

(2) aluminum sheet and bottom plate have a protective ring role, production must be used, available and unavailable bottom plate separate, unified direction placed, check before the board.

(3) Before drilling, it is necessary to check whether the drilling depth meets the requirements and whether the parameters of each drill nozzle are set correctly.

(4) The drilling machine grabs the drill tip and checks whether the position of the drill tip is correct before starting up. The drill tip should not exceed the pressure foot when starting up.

(5) in Zuanzui. The effective length of the drill tip is visually measured and the stack number of available production plates is checked before loading.

(6) If the precision and speed of manual drilling cannot meet the requirements, manual drilling is prohibited.

(7) When drilling special plate to set parameters, according to the quality of the appropriate selection of parameters, the feed should not be too fast.

3. Hole deviation, shift, misalignment

The reasons are as follows: the drill bit deviates during drilling; Improper selection of cover material, soft and hard discomfort; Base material to produce shrinkage caused by hole deviation; Used in conjunction with positioning

Improper use of tools; When drilling pressure foot set improperly, hit the pin to make the production plate move; Resonance occurs during drill operation; Spring collet is not clean or damaged; Production plate, panel offset hole or whole stack offset; The drill bit slides when running the contact cover plate. Scratches or creases on the surface of aluminum sheet of cover plate produce deviation when guiding the drill nozzle to drill down; No pins; Different origin; Adhesive paper is not firmly attached; The X and Y axes of the drilling machine have movement deviation; There is a problem with the program.

Solutions:

(1) a. Check whether the spindle is deflected;

b. Reduce the number of laminations, usually the number of double panel laminations is 6 times the diameter of the drill bit and the number of multi-layer laminations is 2-3 times the diameter of the drill bit;

c. Increase drill speed or reduce feed rate;

d. Check whether the drill tip meets the process requirements, or re-grinding; Check whether the drill tip and drill tip handle have good concentricity;

e. Check whether the fixed state between the drill bit and the spring collet is tight;

f. Test and calibrate the stability and stability of drilling workbench.

(2) Choose the high density 0.50mm lime cover plate or replace the composite cover plate material (the upper and lower layers are 0.06mm aluminum alloy foil, the middle is fiber core, the total thickness is 0.35mm).

(3) according to the characteristics of the plate, before drilling or drilling} after baking plate processing (generally 145C+5C, baking 4 hours shall prevail).

(4) Check or test the dimensional accuracy of the tool hole and whether the position of the upper positioning pin is offset.

(5) Check and reset the presser foot height. The normal presser foot height 0.80mm away from the plate surface is the drilling presser foot height.

(6) Select the right bit speed. Cleaned or replaced spring collet.

(8) The panel is not loaded with pins, and the pins of the control board are too low or loose, so it is necessary to relocate and replace the pins.

(9) Choose the right feed rate or choose a bit with better flexural strength.

(10) Replace the cover aluminum sheet with flat surface and no creases.

(11) Nail plate operation as required.

(12) Record and verify the origin.

(13) The adhesive paper is affixed to the edge of the board at 900 right angles.

(14) Feedback, inform machine repair, debugging and maintenance drill.

(15) Check and verify, and notify the project for modification.