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SMT production line equipment management technology

I. Overview

With the rapid development of China's communication, computer and network and electronic products, the basic technology that supports SMT, which supports the development of high-tech products, has gradually moved from technical exploration to mature actual production and application. The scope of applications has also expanded from a few electronics companies in the past to almost every industry. Only the main members of the SMT Professional Committee of the Beijing Institute of Electronics are from more than 100 companies including electronics, communications, machinery, aviation, aerospace, weapons, ships, home appliances, public security and light industry. Some enterprises have introduced SMT production equipment, which is in good working condition and has achieved gratifying economic benefits and achievements in the application of this technology. In 1998, Beijing's electronics industry achieved a total industrial output value of 45 billion yuan. The Beijing electronics industry has become the first pillar industry to support the economic development of the capital.

However, we should be soberly aware that there are also many applications in which SMT is unfortunate. After spending a lot of foreign exchange to introduce SMT equipment, it can not meet the production requirements, such as design, process and SMT are not suitable; The production process is inefficient and consumes a lot; the product quality level is poor; the SMT equipment is not operating properly, the failure rate is high, the repair and maintenance work cannot keep up, and the late input costs are too large, resulting in long-term idleness of the equipment. At the same time, many companies are investing in SMT equipment in the absence of technical preparation. In addition, with the development trend of foreign SMT, SMT technology and equipment adapting to new products and meeting the latest packaging situation of ICs are constantly emerging. The SMT systems in use are facing the problem of constantly updating technology and equipment. Dongguan computer motherboard processing is inevitable to enterprises. Development has increased new investment risks. To this end, the application of existing equipment, so that enterprises to win higher economic benefits, step into a virtuous circle, and seek new development, I think it has very realistic significance.

Second, the elements involved in SMT

SMT is a system engineering project that involves components and their packaging and tape form, PCB, materials and accessories, design, manufacturing technology and production process, equipment and spare parts, tooling, inspection and management. Sexual production technology, only focusing on a certain link or a certain number of links, can not achieve a good sense of good operation. In the past, some enterprises have a misunderstanding of understanding, that is, SMT is the choice and application of the placement machine equipment. It is considered that the placement equipment is used well and SMT is running well. The actual situation is not so simple, all the links that make up SMT are interrelated.

The design process is not a traditional design idea. It requires technical decision makers and designers to understand and use SMT from a deep level, familiar with equipment and processes, and use and promote SMT on new products and technologies.

1, the selection of components

Master the size, shape and precision of SMD, understand the production process and select components that meet the process requirements, such as meeting the mechanical strength required by automation equipment; adapt to the packaging and braiding of equipment; welding in accordance with reflow and curing processes Thermal performance; corrosion resistance to withstand different cleaning methods;

An IC package form that maximizes device efficiency and reliability.

2, the design process

The so-called design link is also an integrated system. The designers first have a full understanding of the selection of components, especially SMD, and have a certain understanding of the process design of the product. At the design stage, the production process plan should be considered at the same time. In the mass production of products, in order to maximize product quality and production efficiency, lay a very critical foundation. There are quite a few links between the design process and the good use of SMT equipment, such as the requirements of the PCB positioning method and size limit, the range of components that can be mounted on the device, the identification method and requirements of the device for component positioning, and the IC tube leg. Identification, component height dimension and requirements for the maximum number of components.

3. Production technology

It is critical to make full use of the existing SMT equipment to produce high-quality, low-cost products and to determine a reasonable production process plan. After the overall process plan is determined, the procedures and specific parameters of silk screen, dispensing and patching, reflow and curing should be detailed. The common circuit board needs to be assembled by several devices to complete the assembly task. After optimizing the selection of components, path setting, position coordinates and other factors of a single device, it is also necessary to consider the tempo of several devices to avoid the pause of the entire production line. The production process should be based on different process requirements. Carry out the correct process plan and continue to improve in production. The common SMT production process schemes are as follows:

1) Single-sided mounting process

2) Double-sided mounting process

3) Single-sided mixing

4) Double-sided mixing

Third, several steps to strengthen the management of SMT equipment

1. SMT construction plan design

The principle of building a line: applicable, economical, and scalable.

To combine the purpose of SMT use, the nature and type of products to be produced, consider the size and precision of the components and ICs used in the product, the type and quantity of components, the size of the P board required by the product, the scale of production, and the requirements for batch size and quality. , determine the equipment model. According to the product process requirements, combined with the process plan that different types of products may take, determine the function and configuration of the SMT equipment. Scalability must be considered. Due to the rapid development of electronic products and the supporting components industry, Dongguan computer motherboard processing SMT equipment has room for improvement in terms of system function, accuracy, index expansion and production capacity improvement. Choosing the latest equipment and purchasing the options at one time will inevitably lead to excessive investment, and many options are not suitable for many years of idleness, resulting in a large amount of capital and economic downturn. It is necessary to build a SMT production line with complete facilities and strong capabilities. The investment amount is large, and the equipment replacement period is short. Some SMEs are quite difficult to undertake. Enterprises that are determined to purchase, if the application is not effective, will bring a heavy burden to the enterprise. Therefore, when designing the line, it is quite important to choose economical application. The high speed machine is fast and powerful, but the price is about 2 to 3 times that of the medium speed machine. If the type of products produced is not of a small variety and is produced in large quantities, several medium-speed unit lines can be selected, which can solve the problem that the investment capital is too large, and the small amount of funds can be invested multiple times, and the production capacity can be supplemented flexibly. Once the device fails, the impact is minimized. The recycling period of equipment investment is preferably 2 to 3 years.

2. Selection of equipment options and spare parts:

The price of options and spare parts for SMT equipment is quite high and should be determined in conjunction with product requirements and production requirements. Such as dispensing, patch nozzles, cutters, rubber belts, seals, sensors and other consumables can be ordered a certain number of reasonable items, easy to replace in time, component feeders can order appropriate quantities according to the type of components, can improve product replacement Speed, reducing component losses. However, the price of spare parts for equipment and electrical appliances, especially the control circuit board, is quite high, so it is not possible to choose a subscription to reduce the pressure on funds.

3. Professional technical training

After the equipment hardware is determined, you must not ignore the software package. The key to the success of the SMT system lies in the mastery and application of people. Personnel with higher quality should be selected, with the basis of computer automation control, electronics and machinery. For those responsible for equipment maintenance and in-depth mastery of the overall equipment technology, we select technicians with college education or above, after the production line exercise in the early stage, Arrange to go to a foreign manufacturer or manufacturer training center for further study. Planning, purposeful and specific problems and problems, in-depth study, training their own good equipment maintenance and support, will bring benefits to the long-term development of the company. Equipment operators, especially high-speed SMT production lines, also require high-education, high-quality personnel, we choose Chinese technical, secondary school personnel.

4. Acceptance of equipment

Equipment acceptance is one of the key elements in SMT construction.

Acceptance of SMT equipment involves many processes and is very simple to confirm. Although there is currently no set of standardized acceptance methods, we will only use our approach for explanation.

First, in the process of equipment research, mastering structure, performance and technical indicators, signing equipment purchase contracts, etc., it is necessary to consider the contents and methods of equipment acceptance. When the indicators of the equipment technical specifications are confirmed item by item, the detection methods of the key indicators are mastered, and the requirements for equipment acceptance are presented to the manufacturers. For the products that the factory itself wants to produce, you can choose a representative circuit board and prepare the actual production acceptance with the equipment manufacturer in advance.

Equipment installation, adjustment, and environmental layout, electricity and gas supply of the equipment installation site cannot be ignored. Equipment requirements for the environment and energy supply should be met. If it is difficult to achieve due to the conditions, it should be explained in advance with the equipment manufacturer, the two sides determine the countermeasures to avoid the trouble of the final equipment acceptance work.

Formal equipment acceptance is carried out in two phases, which we call no-load acceptance and load-acceptance work. Dongguan circuit board processing

No-load acceptance, that is, according to the various functions of the equipment technical specifications, accuracy indicators and configuration for item-by-item acceptance.

For load acceptance, first use the equipment manufacturer's standard procedures and standard templates for routine acceptance. The second step is to use the circuit board to be produced by the factory for actual production acceptance, and obtain the equipment accuracy, the qualification rate, the speed, the welding quality, the system supporting condition, the product straight-through rate and the pass rate. 5. Improve the daily management level of SMT production equipment:

There are two trends in the trend of failure of different types of SMT equipment:

As time goes by, the longer the usage time, the higher the failure rate, as shown in Figure 1. Of course, there will be a period of relative stability and low failure, and this trend is mainstream.

However, in some devices, the failure rate is relatively high. After a period of use, the fault is relatively reduced, the device enters a stable state, and then gradually transitions to the high-risk zone. Of course, the reason for this change is mainly due to the fact that the equipment is not optimally adjusted and used in the initial stage.

The situation should be more internal to find the reasons for normative management.

The most effective way to reduce equipment failure rate and reduce downtime is to strengthen the equipment management level and formulate management methods and accountability for equipment operation, maintenance and repair.

1) Formulate the overall SMT process route of the whole line, determine the process parameters, data requirements, standards and curves of each equipment unit, and regularly supervise and inspect by the process inspectors according to the prescribed frequency, to prevent the management duties from being unclear and the process management is not strict. The equipment is not maintained according to the regulations, equipment parameters are turbulent, and disordered.

2) According to the provisions of the equipment, formulate daily maintenance, weekly maintenance, monthly maintenance, half-year and one-year maintenance and repair management methods, detailing the parts to be maintained at different stages, the method of operation, the purpose and effect achieved. It is often easy to develop certain systems, and it is quite difficult to implement them consistently. Some operators and even a few managers are afraid of trouble, delaying time and affecting the idea of production. In fact, insisting on maintenance and maintenance, so that the equipment is always in good condition, can greatly improve production efficiency, reduce equipment downtime and maintenance costs, as long as the proceeds will be very significant.

3) Equipment operators should be required to master the basic skills of equipment operation and pass the examination. Operate in strict accordance with the regulations. In the work, we must concentrate on the observation and diligent judgment of the equipment operation process, find abnormal phenomena, solve the problem in time, or ask the maintenance personnel to overhaul, and do not allow the equipment to work.

4) Fully improve the basic quality of employees, change concepts, give full play to the enthusiasm of employees, clarify the relationship between personal interests and factory interests, and formulate production indicators, product quality, equipment qualification rate and integrity rate, consumption of parts and accessories, etc. The initiative is fully mobilized to improve efficiency and reduce consumption.

6. Main measures to improve product quality:

There are many links in the SMT production line, covering all aspects. Around the scope of equipment management, we should focus on several key parts and several monitoring points. The key parts are: screen printing machine, placement machine and reflow oven.

The effect of silk screen solder paste will directly affect the effect of patch and soldering, especially for fine pitch components. First of all, it is necessary to adjust the solder paste, set the pressure, accuracy, speed, clearance, displacement and compensation of the screen printing machine. After the comprehensive effect is achieved, the process setting is stabilized and put into mass production. The quality of the patch, especially the quality level of the high-speed SMT production line placement machine is very critical. If there is a problem, it will have extremely serious consequences. The following work should be done:

1) SMD programming should be accurate and reasonable

The location, sequence, and material placement of components should be arranged as accurately and reasonably as possible. Good procedures will have significant effects in improving patch efficiency and yield, reducing equipment wear and component consumption. After performing the test run of the program and confirming the correctness of the feeder components, the first PCB is placed and arranged for the full inspection. We call it the No. 1 machine to confirm the position and parameters, polarity and direction. Items such as positional offset and damage to the mounted components. After passing the inspection, it started to be put into mass production.

2) Strengthen the quality control and quality feedback of the production process

As the components in production continue to replenish and improve the loading and patching procedures, there will be many opportunities that may cause errors, and in the event of quality accidents, a pre-class inspection and handover system should be established, and each refueling should be done. Self-inspection and mutual inspection to prevent hidden dangers. At the same time, it is necessary to strengthen the quality feedback of the SMT system, and the problems found in the subsequent processes are promptly fed back to the faulty machine, and processed in time to reduce losses.

Control of the reflow device:

PCB reflow effect is closely related to product soldering pass rate, pass rate and other indicators. It is necessary to determine the parameters of each temperature zone according to different PCB boards, different components and different densities and requirements, and according to the standard curve and empirical data of solder paste. Speed, test the temperature curve of the components through the test board, and correct the temperature setting to achieve a high welding pass rate and a stable and reliable state.

Several monitoring points mainly refer to: before the reflow soldering of the patch and before the PCB inspection and repair, set a special monitoring point, which can correct many faults before welding and reduce the repair workload. In addition, during the repair inspection, the main contents and causes of poor quality should be ascertained and summarized, and the equipment that caused the failure should be quickly reported and solved immediately. Dongguan circuit board processing must achieve good work results, have a good work style and work basis, employees should also develop the habits of filling out various basic management project forms and records according to regulations, such as equipment operation daily report, equipment maintenance record sheet, Component exchange checklist, patch status management table, reflow/curing temperature management table, equipment repair and inspection management table, etc. Through these records and statistics, the production status of SMT is continuously improved and improved. Of course, these working methods are applied to the technical service center of Beijing SMT Special Committee, namely Beijing Keli Industrial and Trade Center, which may not be applicable to other units. Technical exchange for your reference, if there are any shortcomings, welcome experts and peers to criticize and correct.

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