SMT mounter common fault analysis and treatment

Preface: when smt mounter malfunction, it is recommended to solve the problem along the following lines:
A, detailed analysis of the smt mounter working order and the logical relationship between them.
B, to understand the fault occurred in the part, link and its degree, as well as the presence of abnormal sound.
C, to understand the operation process before the fault occurred.
D. Whether it occurs on a specific placement head or nozzle.
E. Whether it occurs on a specific device.
F. Whether it occurs on a specific batch.
G. Whether it occurred at a specific moment.

Common fault for:

A, smt placement machine components mount offset mainly refers to the components mount on the PCB after, in X-Y appear position offset, the reasons for its generation are as follows:
(1) the reason of PCB board a: PCB board curvature warp degree exceeds equipment allows range. The upper warp* is big 1.2MM, the lower curve* is big 0.5MM. b: support pin height is inconsistent, resulting in the printed board support is not flat. c: table support platform flatness is bad; d: circuit board technology'> circuit board wiring precision is low, consistency is poor, especially the difference between batch and batch is big.
(2) The blowing air pressure is abnormal when mounting.
(3) mount suction nozzle suction with air pressure is too low, in taking the piece and posting should be in 400mmHG above.
(4) Adhesive, solder technology'>Solder paste coating amount abnormal or deviation. Cause the component to mount when or weld the position to drift, too little cause the component to mount after the table high speed movement to appear to deviate from the original position, the coating position is not accurate, because its tension action and appear to deviate accordingly.
(5) Program data equipment is incorrect.
(6) The substrate positioning is bad.
(7) X-Y working table power member and transmission member between the shaft linker loose.
(8) The movement is not smooth when the mount suction nozzle rises, is more sluggish.
(9) The mount head suction nozzle installation is not good.
(10) Blowing time sequence and mounting head descending time sequence do not match.
(11) Suction nozzle centre data, optical recognition system's camera's initial data set value is bad.

B, smt mount machine device mount angle offset mainly refers to device mount, appear angle direction rotation offset, the main reason of its production has the following aspects:
(1) PCB board reason a: PCB board curvature warp degree exceeds equipment allowable range b: support pin height inconsistent, make printed board support not flat. C: table support platform flatness **. d: circuit board wiring precision is low, consistency is poor, especially the batch and batch between the difference is big.
(2) The blowing air pressure is abnormal when mounting.
(3) Mount suction nozzle suction with air pressure is too low, in taking pieces and posting should be above 400mmHG.
(4) Adhesive, solder paste coating quantity abnormal or deviation.
(5) Program data equipment is incorrect.
(6) The nozzle end is worn, blocked or sticky with foreign matter.
(7) Bad parallelism between nozzle unit and X-Y table or bad detection of nozzle origin.
(8) Mounting nozzle rising or rotating movement is not smooth, more sluggish.
(9) The optical camera is mounted with an improper pillar or data equipment.
(10) blowing air timing sequence and paste loading head down timing sequence does not match.

C, smt placement machine components lost: mainly refers to the components in the suction position and patch position between lost. The main reasons for its generation are the following:
(1) program data equipment error
(2) mount suction nozzle suction with air pressure is too low. In take down and posting should 400MMHG above.
(3) blowing air timing sequence and affixing should fall timing sequence does not match
(4) The posture detection supply sensor is bad, the reference equipment error.
(5) reflector, optical identification camera cleaning and maintenance.

D, smt mounter take parts is not normal:
(1) braided tape specifications and feeder specifications do not match.
(2) vacuum pump did not work or suction nozzle suction air pressure is too low too low.
(3) in the pick-up position braided plastic hot press tape did not peel, plastic hot press tape is not normally pulled up.
(4) The vertical movement system of the suction nozzle is sluggish.
(5) The mounting speed of the mounting head is incorrectly selected.
(6) Feeder installation is not firm, feeder thimble movement is not smooth, fast opening and closing device and pressure tape is not good.
(7) Paper cutting knife can't cut braided tape normally.
(8) The braid cannot rotate normally with the gear or the feeder does not run continuously.
(9) The suction nozzle is not at the low point when the piece is in the suction position, the drop height is not in place or there is no action.
(10) The nozzle centre axis does not coincide with the feeder centre axis lead in the pick-up position and deviates.
(11) Nozzle descent time is not synchronised with piece pick-up time.
(12) There is vibration in the feeder section
(13) Incorrect component thickness data equipment.
(14) The initial value of the suction sheet height is incorrectly equipped.

E, smt mounter randomness does not patch is mainly refers to the suction nozzle in the patch position low point is not to mount appear leakage paste. Its produces the main reason has the following several aspects:
(1) PCB board warp degree beyond the equipment allow range, on warp * large 1.2MM, under the curve * large 0.4MM.
(2) The height of the support pin is inconsistent or the flatness of the table support platform is poor.
(3) The suction nozzle is stuck with cross liquid or the nozzle is seriously magnetized.
(4) Sluggish operation of the L-nozzle vertical movement system.
(5) Mismatch between the blowing timing and the lowering timing of the mounting head.
(6) The amount of glue on the printed board is not enough, the leakage point or the machine inserts the pin too long.
(7) Suction nozzle placement height equipment b bad.
(8) The solenoid valve switch is bad, the blowing pressure is too small.
(9) A suction nozzle appear NG when, device mount STOPPER cylinder action is not smooth, not timely reset.

F, smt placement machine take pieces posture bad: mainly refers to appear stand piece, oblique piece and so on. Its produces the main reason has the following several aspects:
(1) vacuum suction air pressure adjustment is not good.
(2) Sluggish operation of the nozzle vertical movement system.
(3) The nozzle descent time is not synchronized with the suction time.
(4) Incorrect initial setting of suction height or component thickness, incorrect distance between suction nozzle and feeder platform at low point.
(5) Poor specification of the braided tape packaging, component wobbles within the mounting tape.
(6) Poor feeder ejector pin action, fast carrier closure and bad press tape.
(7) The centre axis of the feeder does not coincide with the vertical centre axis of the suction nozzle and the offset is too large.