1. Equipment installation and debugging

 

 

 

From the unboxing of the patch machine, the installation of components, to the level adjustment, the installation of electricity and gas sources, the adjustment of machine system parameters, programming, and finally to trial production, every link should be meticulous and strictly follow the requirements to ensure that The smooth acceptance of equipment ensures long-term, stable and safe operation of the equipment in the future.

 

 

 

1. Equipment installation

 

 

 

Place the machine in place according to the configured production line. First, adjust the height. The installation height of the equipment is mainly based on the main equipment, specifically the height from the upper surface of the track conveyor belt to the ground, which is generally (915±5) mm. Secondly, to adjust the level of the equipment, use a level with a certain accuracy, such as using a level with 1Div=0.02mm/m; the level of the equipment should be adjusted within 0.04mm/m. Third, connect the equipment. There is a certain distance between the equipment. Taking the transmission track as a reference, the spacing is (6±2) mm. Each equipment maintains a line on the horizontal axis, with the inside of the fixed track of the machine as the reference line. If the equipment needs to be elevated, the equipment must be placed on the overall platform during installation. It is prohibited to raise the individual feet supporting the equipment to avoid danger.

 

 

 

2. Debugging

 

 

 

For the initial debugging of the equipment, all parts of the equipment should be in the best possible condition, and a "medical record file" of the equipment should be established to facilitate future work. The debugging of each piece of equipment is a detailed and complex task. Let’s briefly discuss the debugging of the chip placement machine. The debugging of the placement machine is the most common and very important in three aspects: first, the adjustment of the head offset (HeadOffset) value; second, the adjustment of time-related parameters; third, the suction vacuum value and vacuum degree Check the adjustment of vacuum value. They are introduced below.

 

 

 

(1) Adjustment of the head offset value

 

 

 

Under normal circumstances, the system parameters provided by the manufacturer can be used to perform normal work. However, due to various reasons, such as vibration during transportation, changes in lubrication conditions between movable joints, folding and assembly of various components during maintenance, etc., may cause slight changes in their relative positions. The accuracy of this parameter directly affects whether the nozzle can reliably pick up components from the material rack, whether it can place the components in the set position, whether it can reliably complete the simultaneous suction action, etc. Therefore, it is very important to accurately determine the relative positions between the placement heads and between the placement heads and each sensor (such as Beam Sensor). In the specific operation process, you can select a number of points as dispersed as possible within the allowable range of each material rack, each tool, and the PCB, adjust each point, and finally use the average or central value as the sticker. Header offset value to ensure its accuracy and reliability.

 

 

 

(2) Adjustment of time-related parameters

 

 

 

Time-related parameters directly affect the speed of the machine. We know that it takes a certain amount of time for the machine to complete each action. The ideal state is that the machine can complete each action perfectly and in the shortest time. How can we make sure that the time given is just enough without wasting it? This requires experimentation and exploration during machine debugging. Under normal circumstances, the time parameters provided by the manufacturer are given based on conventional machines, or are slightly too large. It can also be adjusted and shortened during the actual debugging process. However, it should be noted that when the placement time is too short, the component will be biased by the suction nozzle. Even if the suction nozzle has no time to put down the component, the placement head will move to the next placement; when the X and Y axis movement of the head is completed, the head starts to move. When the waiting time between the next action and the next action is too short, there will always be a large deviation between the position of the suction nozzle when picking up and placing components and the given position; when the time for picking up components is too short, suction problems will occur. There is no component or stand-up phenomenon. (The phenomenon of standing pieces is mostly caused by incorrect setting of the position of the material rack). It was also found that under the same vacuum suction value, it takes longer to pick up large and heavy components than it does to pick up light and small components. In short, it is very meaningful to continuously accumulate the values ​​of these time-related parameters and their matching relationships during the debugging and production process to increase the speed of the equipment while ensuring quality.

 

 

 

(3) Adsorption vacuum value and vacuum degree detection

 

 

 

Adjustment of vacuum value Different types of placement machines generally use two detection methods to detect whether components are adsorbed. The first is the laser detection method, and the second is the vacuum detection method. For example, the MT-5500II chip placement machine uses the vacuum detection method. The adsorption vacuum value and the vacuum detection vacuum value are two interrelated parameters. When the suction vacuum value is set too high, suction failure will often occur; when the suction vacuum value is set too low, the nozzle will not re-suck or alarm when it cannot suck the component, which will have a great impact on the placement quality of the component. It is a big hidden danger, and it is not easy for operators to find this kind of fault. When the vacuum value for vacuum degree detection is set too high, the head moves to the desired suction point for automatic detection. If the suction pressure value is found to be lower than the set value, the automatic detection will be repeated, affecting normal work; when the vacuum degree detection vacuum value When the setting is too low (lower than the suction vacuum value), system parameter errors will occur. At the same time, for different components, different types of suction nozzles should be used, and the range of suction vacuum values is specified for different suction nozzles. Therefore, the reasonable setting of these two parameters will be complex and important.

 

 

 

When debugging equipment, the participants are very important. It is best for engineers sent by the equipment manufacturer to participate together with factory technicians. Factory technicians not only understand the entire process of equipment installation and debugging, but also know the machine parameters, laying the foundation for future equipment operation, repair and maintenance. Be sure to write a debugging memo after debugging.

 

 

 

2. Equipment acceptance

 

 

 

The placement machine is a relatively expensive piece of equipment. Once you select it, the technical parameters of the placement machine you choose are determined. How to check whether the equipment you purchased meets the requirements you need? This requires certain procedures and specifications to test and accept the technical parameters you require one by one. There are roughly three major steps in acceptance. The first step is the unpacking and acceptance of the machine when it arrives at the factory; the second step is the acceptance after the equipment is installed and debugged; the third step is the acceptance of the machine's performance indicators.

 

 

 

1. Unpacking and acceptance of the machine when it arrives at the factory

 

 

 

After the equipment arrives at the factory, it needs to be unpacked and accepted. The acceptance includes the following aspects.

 

 

 

① Technical information: The accompanying information is complete, including operating instructions, wiring diagrams, parts list, SC program list and maintenance manual, etc. There should also be a "machine placement performance table" in the technical information. This is where the manufacturer conducts data testing on the machine in accordance with the IPC9850 standard, fills the data in the IPC9850-F1 table, and provides it to the user.

 

② Appearance inspection: The equipment has no obvious damage, rust or paint peeling.

 

③ Inventory of random accessories, spare parts and tools: The physical objects should be consistent with the random list and contract list.

 

④ Fill in the "Equipment Unpacking Acceptance Form" and sign it from both parties.

 

 

 

2. Debugging and acceptance after equipment installation

 

 

 

After the equipment is installed, preliminary acceptance will be carried out, mainly including the following contents.

 

 

① Mechanical inspection: During semi-automatic and fully automatic operation, transportation and operation are normal and there is no abnormal noise.

 

② Electrical inspection: Electrical controls are normal, such as operation panel and indicator lights.

 

③ Pneumatic inspection: Pneumatic components are working normally, such as PCB transportation, etc.

 

④ Safety check: All safety sensors are working normally.

 

⑤ Installation height: The installation height of the main equipment is (915±5) mm (the height from the upper surface of the track conveyor belt to the ground).

 

⑥ Horizontal adjustment: The level of the equipment is within 0.04mm/m (use a level of 1 Div=0.02mm/m).

 

⑦ When connecting equipment: the reference line of each equipment is the inside of the fixed side track, and the spacing between the transmission tracks between equipment is (6±2) mm.

 

⑧ After acceptance, fill in the mechanical, electrical, pneumatic and wiring inspection and acceptance form and sign it by both parties.

 

 

 

3. Machine performance acceptance

 

 

 

Carry out inspection and acceptance one by one according to various indicators signed in the placement machine purchase contract. It mainly includes several aspects.

 

 

 

(1) Acceptance of placement accuracy and repeatability and measurement of rotation angle

 

 

 

① Mounting accuracy detection: On the special substrate, mount at the same spacing and continuously mount a certain area. After mounting, use a special measuring instrument to check and measure the error between the actual mounting position and the theoretical mounting position, that is, the average deviation. and standard deviation, and calculate the Cpk value to determine whether the equipment's ability to ensure accuracy meets the requirements of the equipment.

 

② Patch angle detection: On the standard board, mount a circle at the same rotation angle (such as every 5°) and the same radius within the range of 360°. After mounting, use a special measuring instrument to inspect and measure. Calculate the error between the theoretical mounting position and angle and the actual mounting position and angle, and calculate the Cpk value to determine whether the equipment's ability to ensure accuracy meets the requirements of the equipment.

 

 

 

(2) Acceptance of component range

 

 

 

The smallest and largest components that can be mounted on the mounting equipment are inspected with special measuring instruments after mounting to measure the errors in the theoretical mounting position and angle and the actual mounting position and angle to see if they meet the requirements of the equipment. For example, if the machine is stipulated to be able to mount chip components 01005 and integrated circuit IC 0.4 and BGA 0.3mm pitch components, it must be included in the test scope during acceptance and actual testing must be carried out.

 

 

 

(3)Substrate size

 

 

 

When mounting on the largest printed board, especially away from the center area, placement accuracy and repeatability are considered. Mount components back and forth at the maximum distance of the machine's capability. After reaching a certain number, use a special measuring instrument to inspect and measure the error between the theoretical mounting position and angle and the actual mounting position and angle, and calculate the Cpk value to determine the guarantee of the equipment. Accuracy capability and whether it meets the requirements of the equipment.

 

 

 

(4) Mounting speed

 

 

 

Convert the difference between theoretical speed and actual speed. Use a special standard board to perform continuous mounting within the specified range, and then divide the total mounting time by the total number of points to determine whether the time used for each mounting point is within the specified range of the equipment.

 

(5) Testing of software programming

 

 

 

Use 3 placement programs to program on the test machine respectively to check the programming speed.

 

 

 

(6) Inspection of optical vision system

 

 

 

① Substrate recognition system: Mark point detection. There are two methods available. First, use multiple PCBs and Mark points produced by different manufacturers to test the recognition rate of machine recognition; second, design a PCB with different Marek points arranged on it, with different sizes and interference, and detect Machine identification.

 

② Component identification system: performs 3 types of component identification respectively - identification and placement of the smallest components; placement of the most precise components; identification of non-standard components. Use heterosexual components for programming and placement, and check the recognition rate. Component identification can be problematic due to issues with the stamping process and manufacturing tolerances. For example, SOT components produced by multiple manufacturers, especially components with relatively large tolerances, are used for identification and recognition rate statistics.

 

 

 

(7) Nozzle detection and component placement rate

 

 

 

The mounting rate can only be detected by mounting a certain number of components on the device. This is the detection system of the device itself. During testing, all component types that the device can mount, such as chip components, transistors and integrated circuits, etc., must be tested. Only by conducting a placement test can the installation rate of the equipment be fully tested. For example, if 10,000 points are mounted, several components will be thrown away. Generally, 99.98% is used as the standard.

 

 

 

(8) Vibration test of equipment

 

 

 

After the equipment is installed, place a dime coin upright on the top of the machine. When the equipment is running at high speed, see if the coin falls down. If it does not fall over, it proves that the equipment is stable and has little vibration; if the equipment vibrates heavily, you need to consider reinforcing the base and the levelness of the equipment.

 

 

 

4. Equipment reliability

 

 

 

In addition to the acceptance of the appearance and performance of the equipment at that time, the equipment acceptance must also go through a year of running-in of the equipment to gradually understand the characteristics of the equipment and accept the reliability of the equipment. That is, how many failures occur within the equipment operating time (preferably one year), as well as the mean time to failure, etc. If there are frequent breakdowns, or the requirements specified in the contract are exceeded, appropriate negotiations can be made on the final 10% balance.

 

 

 

In addition, due to the limited product batches and limited board models during acceptance, the acceptance results will also have certain limitations. During the warranty running-in period, the number of batches of products attached to the machine also increases. You can also check whether the machine's flexibility and placement speed meet the data requirements provided by the supplier.

 

 

 

3. Acceptance methods and precautions

 

 

 

1. Carry out according to standards

 

 

 

Acceptance shall be carried out in accordance with IPC9850 standard. This method is generally adopted by chip mounter manufacturers. It is difficult for users. The main reason is that the testing methods are limited. The testing instruments are relatively expensive and difficult to implement. If necessary, the manufacturer can be asked to bring instruments for measurement.

 

 

 

For how to measure, please refer to the previous content.

 

 

 

2. Accept according to the test sample

 

 

 

Acceptance based on test boards is a common practice in the industry. Different from the IPC9850 test standard, the standard test mainly includes placement accuracy, repeatability and machine speed; other indicators of the placement machine, such as material loss rate, component range, and vibration, are not covered, and the standard test is a piece of For a kind of component on the glass plate, for patch equipment that covers many components, it has to be tested one by one.

 

 

 

The test board acceptance is to mount all components on a printed board. The printed board is not glass, but a DEMO acceptance board that is actually designed and manufactured. It can be compatible with all types of components, and the angle of the components can be changed and even composed of various components. graphics, the actual placement is carried out during acceptance, and then inspected with other AOI or the printed board CCD of this machine. If necessary, welding and defect rate inspection can also be performed. Test board acceptance basically includes the following aspects.

 

 

 

(1) Acceptance board

 

 

 

The key to this acceptance method is the test sample, whose accuracy and complexity determine the effect of acceptance. Test samples are provided by chip placement machine manufacturers or by customers themselves, but most are provided by manufacturers. Therefore, there are various test samples, and the test boards of different chip mounter manufacturers will be different. In particular, the precision requirements for printed board production must also be strict.

 

 

 

The graphics on the test board include all components specified in the contract and covered by the machine, such as chip components with a minimum of 01005, integrated circuit IC 0.4 and CSP 0.3mm pitch components, etc. There are corresponding component pads on the test board. Various Components are distributed in various parts of the board, such as arranging a certain number of chip components at the four corners and center of the board, interspersed with CSP, QFP and BGA components.

 

 

 

The larger the size of the test board, the better. It is best to use the maximum size of the equipment, such as 300mm × 250mm; the board thickness is 1.6mm; the manufacturing accuracy of the test board is higher than the general printed board manufacturing requirements, especially the accuracy requirements of pad size and spacing. High, it is generally required that the pad size accuracy is ±0.01, and the pad size pattern and pins are 1:1 to avoid errors caused by printed board manufacturing that affect the measurement results. The greater the number of printed boards, the better, in order to facilitate data statistics and the more credible the test results will be. The minimum quantity is considered based on photo components; such as the placement of chip componentsThe number is not less than 10,000. If 1,000 chip components are designed on the board, 10 boards must be mounted to have statistical effect. Please refer to the picture below for the test board pattern.

 

 

 

(2) Acceptance components

 

 

 

Acceptance components can be real components, generally chip components and QFP components are real components; analog components can also be used, such as integrated circuits QFP, BGA and CSP. Components provided for acceptance must comply with relevant technical specifications, thus eliminating errors in test results due to component errors.

 

 

 

 

 

(3) Test steps

 

 

 

The first step is to prepare for formal mounting. Number the printed boards and paste double-sided tape with appropriate viscosity; at the same time, load components, machine programming and debugging. The second step is to perform formal placement and record. Test and install the test boards in sequence. Various required data are recorded during placement. For example, the timer records the transmission time, placement time and the throw rate during machine placement. The third step is to collect and process data on the mounted printed boards. The placement results are measured and data collected using AOI, a reading microscope and the CCD of the machine itself.

 

 

 

(4) Data processing

 

 

 

Perform data statistics and processing on test data. According to the calculation method in Chapter 1, calculate the placement speed, placement accuracy, repetition accuracy, rotation accuracy, etc.; at the same time, through testing, you can also get the CCD recognition ability, throw rate and the accuracy difference between the edge and the middle of the printed board, etc. .

 

 

 

(5) Determine whether the equipment is qualified

 

 

 

Compare the actual data obtained with the given data to find out the differences and determine whether the various indicators of the equipment meet the requirements stipulated in the contract.

 

 

 

3. Acceptance based on actual products

 

 

 

Conduct trial production of actual products on the SMT production line, and evaluate the quality of the placement machine based on the actual production results. This method is suitable for large-scale production, and the products are generally relatively stable. The actual products selected should be representative to a certain extent, including a wide range of components. For example, the smaller the chip capacitors and resistors, the better, preferably 0201; the pin spacing of IC components should preferably reach 0.4mm, and the larger the IC size, the better. The more pins the better; BGA components must require mounting acceptance, and CSP with a pitch of 0.5mm has been widely used. It is best to have a certain batch size for acceptance production, so that certain statistical data, such as speed and accuracy, can be judged and compared. It's more convincing. The judgment of actual product placement is relatively rough, mainly based on visual inspection, which can generally be made by referring to the displacement in the IPC-610-D Level 3 standard. If the side offset of the QFP component pin does not exceed 25% of the pad, it is qualified, but the toe is not allowed to offset; the same is true for chip resistor-capacitor components, the side offset does not exceed 25% of the pad, and the toe is not allowed. Offset is allowed. BGA components that offset the pad by 50% are considered unqualified. After a certain batch of production and testing, the failure rate of all placements should not exceed 1 [illustration]. Since the actual production still needs to be completed by welding, the finished product is a finished product, and the rate of bad solder joints and the through rate can be calculated. Conduct a comprehensive assessment of SMT production lines.

 

 

 

This method is simple and was widely used in early SMT production line acceptance. However, it is often a rough method and cannot quantitatively describe various indicators of the placement machine. Sometimes you can't find problems with the machine, or even if the equipment fails to meet the specified indicators, you have no way to check it out. In addition, the complexity of the acceptance board will also affect the acceptance results. Therefore, it is recommended that qualified manufacturers adopt the first and second sets of solutions for acceptance.

 

 

 

4. Precautions for performance acceptance

 

 

 

① The actual measurement data does not exceed 25% of the data provided by the supplier. For example, the placement speed is not less than 75% of the theoretical speed.

 

② The measurement of the accuracy of the placement machine is based on reality. The Z-axis is higher than the X- and Y-axis. Especially for the placement of small components, precise control of the Z-axis is a means of controlling the defect rate. Therefore, using small components such as 01005 to accept placement is not only a test of accuracy, but also a test of Z-axis control of the placement machine.

 

③ It is not only necessary to conduct accuracy inspection, but also to conduct actual welding of the printed board. Both test boards and actual product acceptance can be performed with actual welding, allowing a comprehensive check of the integrity of all equipment along the entire production line.

 

④ When mounting small components 0402, 0201 and 01005, if a glass PCB is used, double-sided tape can be used as an adhesive instead of lubricating grease, which is closer to the actual effect.

 

⑤ Before testing, you can refer to the IPC9850 standard and prepare the experimental instructions.

 

⑥ The provided components and related auxiliary materials (such as double-sided tape, grease and glass plates, etc.) should comply with relevant technical specifications.

 

⑦ The posted board should 100% meet the SMT inspection specifications and equipment accuracy requirements, that is, during the continuous placement of 5,000 points, there will be no missed placement, no placement position completely deviating from the pad, and no upright or vertical placement.

 

⑧ The production information recorded by the equipment should meet: adsorption rate ≥ 99.95%, filling rate ≥ 99.90%.

 

 

 

5. Acceptance form

 

 

 

After comprehensive testing and acceptance assessment of the purchased equipment, you need to fill in the equipment installation acceptance form to determine whether it is qualified or not.