Joy Technology Co.,Limited

How to choose SMT equipment？



SMT equipment in the purchase of the main consideration of the placement accuracy and placement speed in the actual use of the process, in order to effectively improve product quality and reduce production-cost-conducive to improve production efficiency, how to improve and maintain SMT equipment placement rate is The primary problem facing the user.

First, the meaning of the rate of placement The so-called placement rate refers to the device in a certain period of time the actual number of mounted and suction ratio, that is: mount rate = × 100% adsorption number of which the total number of pieces is the number of adsorption errors, identification The number of errors, the number of pieces, the number of lost, etc., and identify the error sub-device size error and poor optical identification device two. Mounter Whether it is minicomputer, medium-sized machines, mainframes, both medium-speed machines, high-speed machines, they are mainly by the device storage device, XY table, placement head and control system components. The placement head is the core and key components of the placement machine. The placement head generally has a fixed head and a rotating head. Generally, the fixed head is arranged in a plurality of positions, at least two, as many as eight, and can be taken at the same time or separately. The rotating head Divided in the horizontal plane of rotation and rotation in the vertical plane.
A, the device suction nozzle suction height switch
B, θI rotation (± 90 ')
C, optical identification device
D, Device attitude detection θ2 rotation (± 90 ')
E, mount device / nozzle height switch
F, θ3 rotation (± 180'-θ) Nozzle origin detection defective excluded
G, nozzle conversion
H, nozzle number detection pick-up from the placement machine
Placement of the entire process, simply from the equipment point of view, the right to set the nozzle pick-up height, pick-up nozzle center and the relative position of the feeder case, the main factor affecting device placement rate is pick-up location According to the statistics of production equipment and information, the impact will account for more than 80% of the total influencing factors. The reasons are as follows: on the one hand, the feeder on the device storage and transportation device and on the other hand the nozzle, both of which are about 60% of the feeders' films, and about 40% are caused by the nozzle pollution.


Second, the impact of feeders Feeders affect the owner focused on feeding anomalies.
Feeder drive motor drive, mechanical drive and cylinder drive several, where the mechanical drive, for example, shows the impact of feeders on the placement rate:
1, the drive part of the wear and tear of the mechanical drive by the cam spindle drive the feeding mechanism, quickly knocked looking for the feeder arm, through the connecting rod connected to the ratchet drive component parts advancing a distance, while driving the plastic The tape reel will tape the plastic tape cap off, the suction nozzle descends to complete the pickup action. However, as the feeding mechanism accesses the feeder at a high speed, after a long time of use, the pawl of the feeder is severely worn, causing the pawl not to drive the plastic strip of the reel to be peeled off normally, so that the nozzle can not finish the pickup work. Therefore, before installing the tape should carefully check the feeder, the pawl wheel worn feeder should be repaired immediately, can not be repaired should be promptly replaced.
2, the structure of the feeder deformation due to long-term use or improper operation of the operator, the pressure plate cover, thimble, spring and other movement agencies produce deformation, corrosion, etc., resulting in device sucker, legislation or suction devices, Therefore, regular inspection should be carried out to find out the problems should be dealt with promptly so that a great amount of wasted equipment will not be wasted. At the same time, the installation feeder should be correctly and firmly installed on the feeding platform, especially the equipment without feeder height detection, otherwise Damaged feeders or equipment.
3, poor lubrication of the feeder General feeder maintenance and care, it is easy to be ignored, but regular cleaning, cleaning, lubrication lubrication is an essential work.

Third, the impact of nozzle The nozzle is also affecting the placement rate is another important factor, the reasons for internal reasons, but also external reasons
1, the internal reasons on the one hand is the lack of vacuum negative pressure, suction nozzle pick-up before the automatic conversion of the mechanical head mounted on the nozzle, converted to true by the inflatable it adsorbed to produce a certain negative pressure, when the suction parts, the negative pressure sensor When the detection value is within a certain range, the machine is normal, and vice versa. Generally, the negative pressure at the pick-up position to the mounting nozzle should be at least 400mmHg. When the negative pressure of large devices should be over 70mmHg, the filter in the vacuum pump should be cleaned periodically to ensure enough negative pressure. At the same time should be regularly checked negative pressure sensor working state. On the other hand, the filter on the mounting head and the filter on the suction nozzle are black due to the pollution or clogging of the surrounding environment or the gas source. Therefore, the filter should be replaced on a regular basis, the filter on the nozzle should be replaced at least half a month, the filter on the head should be replaced at least six months to ensure smooth airflow.
2, the external causes of the one hand, the pressure relief of the air supply circuit, such as rubber pipe aging, rupture, seal aging, wear and wear after prolonged use of the nozzle, on the other hand due to adhesives or dust in the external environment, Due to the daily cleanliness of the suction nozzle, it is possible to monitor the pick-up condition of the suction nozzle at any time, and to prevent the clogging or bad pickup of the suction Mouth should be promptly cleaned or replaced to ensure good condition, while installing the nozzle, you must ensure that the correct, solid installation, otherwise it will cause nozzle or equipment damage.

Fourth, the device detection system is the placement accuracy and placement of the necessary guarantee of correctness
Device detection system is divided into device light recognition system and device attitude detection
1, optical identification system is a fixed installation of an optical camera system, which is mounted head rotation process by the camera to identify the contours of the components to optical imaging, while the relative position and angle of rotation of the camera with the camera device to measure and record Down, and transmitted to the drive control system, in order to XY coordinate position deviation and θ angle deviation compensation, the advantage lies in the accuracy and flexibility applicable to a variety of shape and shape of the device. It has a reflection of the identification method to identify the device electrode, identification accuracy from the nozzle size, the general SOP, QFP, BGA, PLCC and other devices using reflection recognition. The transmission identification method is based on the component shape to identify the recognition accuracy by the nozzle size when the nozzle shape is larger than the outline of the device to identify the image in the nozzle profile. As the light source of the optical imaging system after a period of use, the light intensity will gradually decline, because the light intensity and solid-state camera conversion is proportional to the gray value, the greater the gray value, the clearer the digital image. So with the reduction of light intensity of the light source, the gray value also decreases, but the gray value stored in the machine does not automatically decrease as the light intensity decreases, when the gray value is lower than a certain Value, the image will not be recognized, so you must regularly carry out the calibration test ① re-school ② adjust the iris focal length. The gray value will be proportional to the light intensity of the light source. When the light intensity of the light source is too weak to recognize the device, the light source must be replaced. At the same time, the lens, the glass plate and the dust on the reflector should be cleaned periodically to prevent the light source from being affected by the dust or the device, resulting in poor recognition. The camera must also be properly set the initial data.
2, the whole posture detection is through the linear sensor mounted on the rack, from the device for high-speed scanning in the horizontal to detect the device's state of adsorption, and accurately detect the thickness of the device, when the library set the thickness of the value and the measured value Exceeding the allowable error range, poor thickness detection may occur, resulting in loss of parts. Therefore, it is very important to correctly set the data of the parts in the parts store and the reference data of the thickness check and control. The thickness of the parts must be checked frequently. At the same time, the linear sensor should be cleaned regularly to prevent the adhesion of the dust, debris, oil and other devices on the thickness and adsorption status of the detection.

Fifth, the poor accuracy of device mounting accuracy device is a multi-factor results, in addition to the reasons for the device itself, the device also has a bad influence on it, mainly in:
A, Perforation pitch error larger.
B, the device shape is not good.
C, Tapered square hole shape irregular or too large, resulting in the device is caught or horizontal flip.
D, tape and plastic hot pressing tape is too large, can not be properly peeled off, or the device is stuck in the bottom of the belt.
E, there is oil on the bottom of the device.

Sixth, placement machine common fault
1, when a fault occurs, it is recommended to solve the problem as follows:
A, a detailed analysis of the working order of the device and the logical relationship between them.
B, to understand the location of the fault, the link and its extent, and whether there is abnormal sound.
C, understand the operation of the fault before the operation.
D, whether it occurs in a specific placement head, nozzle.
E, occurs on a specific device.
F, occurs on a specific lot.

G, is it happening at a particular time?

2, analysis of common faults

A, component placement offset mainly refers to the components and components mounted on the PCB, the position of the X-Y offset occurs, the reason is as follows:
(1) PCB board reason a: PCB board curl degree beyond the allowable range of equipment. Upturned up to 1.2MM, under the song the largest 0.5MM. b: inconsistent support pin height, resulting in uneven printed circuit board support. c: table support platform flatness bad d: low-precision circuit board layout, consistency is poor, especially between large quantities and large differences.
(2) mounted suction nozzle suction pressure is too low, pickup and placement should be above 400mmHG.
(3) blowing pressure when mounted abnormal.
(4) adhesive, solder paste coating amount abnormal or deviation. Resulting in component placement or welding position drift occurs too little lead to component placement in the table when the high-speed movement deviate from the original location of the coating is not accurate, due to the role of tension and the corresponding shift.
(5) program data equipment is not correct.
(6) poor positioning of the substrate.
(7) When the nozzle is mounted, the movement is not smooth and slow.
(8) X-Y table loose coupling between power unit and transmission unit.
(9) placement head nozzle installed bad.
(10) The blowing timing does not match the placement head drop timing.

(11) The nozzle center data, the initial data of the camera of the optical recognition system are set incorrectly.

B, the device placement angle offset refers to the device mounting, there is a shift in the direction of rotation, the main reasons for its occurrence in the following areas:
(1) PCB board reason a: PCB board curl Alice beyond the allowable range of equipment b: inconsistent support pin height, so that printed circuit board support uneven. C: poor support platform flatness. d: low-precision circuit board layout, consistency is poor, especially large differences between batch and batch.
(2) mounted suction nozzle suction pressure is too low, pickup and placement should be above 400mmHG.
(3) blowing air pressure abnormalities.
(4) adhesive, solder paste coating amount abnormal or deviation.
(5) program data equipment is not correct.
(6) The end of the suction nozzle is worn, clogged or stuck with foreign matter.
(7) mounting nozzle rising or rotating movement is not smooth, more sluggish.
(8) Defective parallelism between nozzle unit and X-Y table, or bad nozzle origin detection.
(9) Improper installation of optical camera or data equipment.

(10) The blowing timing does not match the placement head drop timing.

C, the components are missing: The main component refers to the location of the suction piece and the patch position is lost.
The main reasons for its emergence in the following areas:
(1) program data device error
(2) mounted suction nozzle suction pressure is too low. In the removal and placement should be more than 400MMHG.
(3) inflatable timing and placement should drop timing does not match
(4) attitude detection for the sensor bad, the reference equipment error.

(5) reflector, optical recognition camera cleaning and maintenance.

D, pick up is not normal:
(1) Taping specifications do not match the feeder specifications.
(2) vacuum pump is not working or nozzle suction pressure is too low too low.
(3) In the pick-up position of the plastic hot pressing tape did not peel, plastic hot pressing belt is not properly pulled.
(4) nozzle vertical movement system slow.
(5) placement head mount speed selection error.
(6) Feeder installation is not solid, unsmooth feeder thimble, fast shutter and pressure with bad.
(7) Cutting knife can not be normal cut with tape.
(8) Taping can not rotate normally with the gear or the feeder operation is not continuous.
(9) suck suction nozzle position is not low, the descent height is not in place or no action.
(10) In the pick-up bit nozzle center axis and feeder center axis lead does not coincide, there deviate.
(11) Nozzle descent time and suction time are not synchronized.
(12) Feeding department has vibration
(13) Component thickness data The device is not correct.

(14) The initial value of suction height is incorrect.

E, randomness is not the patch is mainly refers to the nozzle position in the patch is not posted posted low posted.
The main reasons for its emergence in the following areas:
(1) PCB board warpage beyond the scope of equipment Xu, up 1.2MM, under the song the largest 0.4MM.
(2) inconsistent support pin height or poor support platform flatness.
(3) nozzle mouth sticky liquid or nozzle is seriously magnetized.
(4) L nozzle vertical movement system slow operation.
(5) The timing of air blowing does not match the descending timing of the placement head.
(6) PCB less than the amount of plastic, leakage or machine plug pin is too long.
(7) nozzle mount height of the device is not good.
(8) poor switching solenoid valve, inflatable pressure is too small.

(9) When a nozzle NG, the device mounted STOPPER cylinder slow motion, not reset in time.

F, pick bad posture: mainly refers to the legislation films, oblique and so on.
The main reasons for its emergence in the following areas:
(1) vacuum suction pressure regulator is not good.
(2) nozzle vertical movement system slow.
(3) nozzle descent time and suction time is not synchronized.
(4) The initial value of the suction piece height or the component thickness is set incorrectly, and the distance between the suction nozzle and the feeding part platform is not correct when the suction nozzle is at a low point.
(5) Tape packaging specifications are poor, the components in the installation of the band shaking.
(6) Feeder thimble poor action, fast loadlock and pressure with bad.
(7) Feeder center axis and nozzle vertical center axis do not coincide, the offset is too large.

Seven, basic management How to make good use of good performance equipment to create the maximum profit, is the pursuit of business goals, how to achieve the goal, mainly by scientific management methods:

A, establish regular staff training system, improve staff quality. People are the soul of the enterprise, which is the root of the enterprise's business and development. Therefore, we must pay attention to the training of staff skills and ideological concepts should be proficient and correct operation of the equipment, the correct installation, use of feeders, regular maintenance, maintenance of equipment, to effectively ensure product quality, reduce material consumption, improve production efficiency .

B, establish regular equipment maintenance plan. Promote the TPM management, the implementation of preventive performance maintenance and overhaul, thereby reducing equipment downtime due to temporary failure surface, the pursuit of maximum equipment utilization efficiency.

C, improve equipment maintenance files. 

① maintenance records. Record the phenomenon of failure, analysis process, handling, spare parts replacement. 

② dimensional spare parts replacement records. Analysis of the reasons for spare parts replacement, spare parts replacement cycle, reduce spare parts backlog of capital, reduce production costs.

D, improve equipment operation file.

 ① equipment operating status timely registration form.

 ② equipment operation