Common problems and solutions of PCB drilling?

The reasons are: the main shaft deflection is too large; Improper operation of CNC drilling rig during drilling; Improper bit selection; The bit speed is insufficient and the feed speed is too high; There are too many layers stacked; There are sundries between plates or under cover plates; When drilling, the depth of the spindle is too deep, which leads to poor chip removal of the bit and hanging drilling; Too many grinding times or over-life use of the drill bit; The cover plate is scratched and wrinkled, and the padding is uneven; When fixing the bottom plate, the adhesive tape is too wide or the aluminum sheet and plate of the cover plate are too small; Excessive feeding speed causes extrusion; Improper operation when filling holes; The ash blocking under the aluminum plate of the cover plate is serious; There is a deviation between the center of welding drill tip and the center of drill handle.

Solution:

(1) Inform the mechanic to repair the spindle or replace it with a good one.

(2) A, check whether the beriberi pipeline is blocked;

B, adjust the presser foot pressure according to the bit state, and check the pressure data when the presser foot is pressed down, which is normally 7.5kg.

C, check the spindle speed change, whether there is copper wire at the clamping mouth that affects the speed uniformity;

D, detecting the change of the spindle speed and the stability of the spindle during drilling; (Can be compared between spindle and spindle)

E, carefully adjust the state between the presser foot and the drill bit. Don't expose the presser foot of the drill tip, and only allow the drill tip to be 3.0mm inside the presser foot.

F, detect the parallelism and stability of the drill floor.

(3) Check the geometry and wear of the drill bit, and select the drill bit with the appropriate length of the chip removal groove.

(4) Select the appropriate feed speed and reduce the feed speed.

(5) Reduce an appropriate number of overlapping layers.

(6) When placing the board, clean up the sundries under the board surface and the cover plate, and keep the board surface clean.

(7) Inform the mechanic to adjust the drilling depth of the spindle to keep a good drilling depth. (Normal drilling depth should be controlled at 0.6mm.)

(8) Control the grinding times (according to the work instruction) or strictly set the parameters in the parameter table.

(9) Choose a cover and pad with suitable and flat surface hardness.

(10) Carefully check the fixing state and width of the adhesive tape, replace the aluminum cover plate and check the plate size.

(1 1) Reduce the feed speed appropriately.

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

(13) a. Check whether the presser foot height and presser foot exhaust groove are normal;

B, the suction is too large, you can appropriately reduce the suction.

(14) Replace the drill bit in the same center.

2. Hole loss

The reasons are as follows: the drill bit is taken out after breaking; There is no aluminum sheet or reverse bottom plate when drilling; Parameter error; The drill bit is slender; The effective length of drill bit can't meet the needs of drill pile thickness; Hand drilling; The board is special and is caused by the leading edge of the batch.

Solution:

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

(2) Both the aluminum sheet and the bottom plate play the role of protecting the small holes, so they must be used in production. Available and unavailable bottom plates should be placed separately and in the same direction, and checked again before putting the plate.

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

(4) The drilling rig grasps the drill nozzle and checks whether the clamping position of the drill nozzle is correct before starting. When starting the machine, the drill nozzle generally cannot exceed the presser foot.

(5) Before drilling, visually check the effective length of the drilling hole, and measure and check the stacked number of available production plates.

(6) Manual drilling and cutting accuracy, speed, etc. Can not meet the requirements, so it is forbidden to drill holes by hand.

(7) When setting the drilling parameters of special plates, the parameters should be selected reasonably according to the quality situation, and the feed should not be too fast.

3, hole deviation, displacement, dislocation.

The reasons are as follows: the drill bit deviates when drilling; Improper selection of cover material, soft and hard discomfort; The substrate expands and contracts, resulting in hole position deviation; Improper use of matching and positioning tools; When drilling, the presser foot is improperly set, and the production plate moves when it touches the pin; * * * The drill bit vibrates during operation; The spring chuck is not clean or damaged; Deviation of hole position or overall stacking position of production plates and panels; The drill bit will slide when it contacts the cover plate during work; There are scratches or creases on the surface of the aluminum sheet of the cover plate, which leads to deviation when guiding the bit to drill; Not nailed; Different origins; The tape is not firmly attached; There is movement deviation between X axis and Y axis of drilling machine; There is something wrong with the program.

Solution:

(1) A, check whether the spindle is skewed;

B, reduce the number of laminations, usually the number of double-faced laminations is 6 times of the diameter of the drill bit, and the number of multi-layered laminations is 2-3 times of the diameter of the drill bit;

C, improve the bit speed or reduce the feed speed;

D, check whether the drill nozzle meets the process requirements, or re-sharpen;

E, check whether the drill tip and drill handle are in good concentricity;

F, check whether the fixed state between the drill bit and the spring chuck is fastened;

G, detecting and correcting the stability and stability of the drilling workbench plate.

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

(3) According to the characteristics of the plate, bake the plate before or after drilling (generally,145℃ 5℃, baking for 4 hours shall prevail).

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

(5) Check the height of reset presser foot. The normal presser foot height is 0.80mm from the board surface, which is the best presser foot height for drilling.

(6) Select the appropriate bit rate.

(7) Clean or replace the spring chuck.

(8) There is no bolt installed in the panel, and the bolt of the control panel is too low or loose, so it is necessary to reposition and replace the bolt.

(9) Select a suitable feed speed or a bit with good bending strength.

(10) Replace aluminum plate with flat surface and no wrinkles.

(1 1) Nail the boards as required.

(12) Record and verify the source.

(13) Stick the adhesive tape to the edge of the board at a 90-degree right angle.

(14) feedback, notify the mechanic to debug and maintain the drilling rig.

(15) Check and verify, and notify the project to make modifications.

4. Macroholes, small holes and twisted apertures

The reasons are: the specifications of the bit nozzle are wrong; Incorrect feed speed or rotation speed; Excessive wear of drill bit; Too many times to regrind the drill bit or the length of the chip removal groove is lower than the standard; Excessive deflection of the spindle itself; The drill tip collapses and the aperture becomes larger; The aperture is wrong; The borehole diameter was not measured when replacing the drill bit; The drill bit arrangement is incorrect; The position is wrong when changing the drill bit; Aperture diagram not checked; The spindle can't put down the cutter, which leads to the cutter pressing; Wrong serial number was entered in the parameter.

Solution:

(1) Before operation, check whether the drill bit size and instructions of the control system are wrong.

(2) Adjust the feed speed and rotating speed to the most ideal state.

(3) Replace the drill nozzle and limit the number of holes drilled by each drill nozzle. Usually, 3000~3500 holes can be drilled by pressing two panels (four in each stack); 500 holes can be drilled on the high-density multilayer board; For FR-4 (three in each stack), 3000 holes can be drilled; For the hard FR-5, the average decrease is 30%.

(4) Restrict the change of regrinding times and regrinding size of drill bit. Drilling multi-layer board, allowing grinding once every 500 holes and grinding for 2~3 times; Every 1000 holes can be ground once; For every 3000 holes drilled in the double panel, sharpen it once, and then drill 2500 holes; Grind again and drill 2000 holes. Re-grinding the bit in time can increase the number of re-grinding and prolong the life of the bit. The wear depth of the whole length of the two main cutting edges should be less than 0.2 mm, measured by a tool microscope. When regrinding, 0.25mm should be removed. Fixed handle drill can be reground for 3 times; The shovel teeth were reground twice.

(5) Feedback to the maintenance dynamic deflection tester to check the deflection of the spindle during operation, and repair it by a professional supplier if it is serious.

(6) Before drilling, check the tool surface with a 20-fold mirror, and grind or discard the bad bit.

(7) Check and measure for many times.

(8) When replacing a drill bit, you can measure the replaced drill bit, and the replaced drill bit can measure the first hole drilled.

(9) When arranging bit nozzles, count the positions of the tool magazine.

(10) Please read the serial number clearly when replacing the drill bit.

(1 1) When preparing tools, check the actual aperture of the aperture diagram one by one.

(12) Clean the clamping nozzle, and carefully measure and inspect the tool surface after pressing the tool.

(13) Please check carefully when entering the tool serial number.

5. Lost drilling

The reasons are: the drill bit is broken (unclear identification); Halfway; Program error; Unintentionally delete the program; The rig missed reading when reading data.

Solution:

(1) Separate the broken drill boards and check them one by one.

(2) Start the machine again after stopping halfway, and return to 1~2 hole to continue drilling.

(3) Once it is determined that it is an engineering program error, it is necessary to immediately notify the engineering change.

(4) During the operation, the operator shall try not to change or delete the program at will, and notify the engineering treatment when necessary.

(5) After reading the file through CAM, change the machine for production and notify the machine for maintenance.

6. Batch Preposition

The reasons are: wrong parameters; The drill bit is badly worn and the blade is not sharp; The density of bottom plate is not enough; There are sundries between the substrates and between the substrates and the bottom plate; The substrate is bent and deformed to form a gap; Uncoated board; The plate material is special.

Solution:

(1) When setting parameters, strictly follow the parameter table, and check and verify after setting.

(2) When drilling, control the service life of the drill bit, and do not use it beyond the service life according to the service life table.

(3) Test the density of the bottom plate.

(4) Clean up the sundries between the substrates when nailing the boards, and wipe the board surface with a rag when stacking the multilayer boards.

(5) The deformation of base plate should be compacted to reduce the gap between plates.

(6) The cover plate is used to protect and guide the drilling. Therefore, aluminum sheets must be added when drilling. (Used for drilling holes with impermeable and aluminizable sheets)

(7) When setting the drilling parameters of special plates, the parameters should be selected reasonably according to the quality situation, and the feed should not be too fast.

7. The hole is not drilled (not through the substrate)

The reasons are: improper depth; The drill bit length is not enough; The bed board is uneven; The thickness of the backing plate is uneven; Half of the broken knife or drill bit is broken, and the hole is not penetrated; Impermeability is formed after the batch of copper is sunk into the hole; The spindle clamp is loose, and the drill nozzle becomes shorter when drilling; Unclipped bottom plate; Two pads were added when making the first board or filling holes, but they were not changed during production.

Solution:

(1) Check whether the depth is correct. (Total depth and depth of each spindle)

(2) Measure whether the length of the bit nozzle is enough.

(3) Check whether the bedplate is flat and adjust it.

(4) Measure whether the thickness of the backing plate is consistent, feedback and replace the backing plate.

(5) Positioning and re-drilling.

(6) If the source of batch front is checked and eliminated before, the batch front is polished.

(7) Adjust the tightness of the spindle and clean or replace the sleeve.

(8) Check whether there is a bottom plate before installing double panels.

(9) Make a good mark, and after drilling the first board or hole filling, change it back to the original normal depth.

8. Curled fragments appear on the panel.

The reason is that the cover plate is not used or the drilling process parameters are not selected properly.

Solution:

(1) Suitable cover plates shall be used.

(2) Under normal circumstances, we should choose to reduce the feed speed or increase the bit speed.

9. Plug hole (plug hole)

The reasons are: the effective length of drill bit is not enough; The depth of the drill bit drilling into the liner is too deep; Material problems of the substrate (moisture and dust); The liner is reused; Improper processing conditions, such as insufficient dust suction; The structure of the drill bit is not good; The feed speed of the bit nozzle is too fast, and the rising speed does not match.

Solution:

(1) Select the appropriate drilling length according to the stacking thickness, which can be compared with the stacking thickness of production plates.

(2) Set the drilling depth reasonably (the drilling tip should be controlled to drill into the backing plate by 0.5mm).

(3) Before drilling, select or bake good quality base materials (generally bake at 65438 045℃ for 4 hours).

(4) The backing plate should be replaced.

(5) Select the best processing conditions, and properly adjust the drilling dust suction force to reach 7.5kg per second.

(6) Replace the supplier of drill nozzle.

(7) Set parameters in strict accordance with the parameter table.

10, rough hole wall

The reasons are as follows: the feed quantity changes too much; Feed speed is too fast; Improper selection of cover materials; Insufficient vacuum (air pressure) of fixed bit; Improper tool recovery rate; The cutting leading edge of the top corner of the drill bit is broken or damaged; The spindle deflection is too large; Poor chip removal performance.

Solution:

(1) Keep the optimum feed speed.

(2) Adjust the feed speed and rotation speed according to experience and reference data to achieve the best matching.

(3) Replace the covering material.

(4) Check the vacuum system (air pressure) of the CNC drilling rig, and check whether the spindle speed has changed.

(5) Adjust the retracting speed and bit speed to achieve the best condition.

(6) Check the usage of the drill bit or replace the drill bit.

(7) Check and clean the spindle and spring chuck.

(8) Improve chip removal performance, and check the state of chip removal groove and cutting edge.

1 1 There is a white circle at the hole edge (the copper layer at the hole edge is separated from the substrate, and the hole is blasted).

Causes: Thermal stress and mechanical force lead to local fracture of the matrix during drilling; The size of the woven yarn of glass cloth is relatively thick; The quality of base material (cardboard) is poor; Overfeeding; The drill bit is loose and the fixation is not firm; There are too many layers stacked.

Solution:

(1) Check the wear of the drill bit, and then replace or regrind it.

(2) Choose glass cloth woven with fine glass filaments.

(3) replace the substrate material.

(4) Check whether the set feed is correct.

(5) Check whether the diameter of the drill handle and the clamping force of the spindle spring clamp are sufficient.

(6) Adjust the lamination data according to the process regulations.

The above are common problems in drilling production, so more measurements and inspections should be made in actual operation. At the same time, strictly regulating the operation is of great benefit to controlling the quality failure of drilling production and improving the product quality and production efficiency.