SMT PCB assembly companies' desoldering principles

PCB assembly companies in USA, after checking the welding quality of the electronic components, dissolder the defective electronic components. In order to remove miswelded electronic components without damaging other components and PCB circuit boards, it is necessary to master the PCBA processing and testing skills. The basic principles of diswelding of PCB assembly companies are as follows :

1. Do not damage the components, wires and surrounding components to be removed.

2. PCB assembly companies shall not damage the welding pad and printed wire on the PCB circuit board during diswelding. 

3. For the electronic components that have been judged to be damaged, the pins can be cut first and then removed, which can reduce the damage of PCB assembly companies.

4. Try to avoid moving the location of additional original devices, if necessary, must do a decent job of restoration.

The basis for SMT PCB assembly companies in USA

The high quality basis of PCB assembly companies in USA must have high quality components, advanced SMT production equipment, and high quality production capacity. It is believed that many customers have a headache when looking for high-quality PCB assembly companies in USA. Then how to judge whether PCB assembly companies in USA have high-quality basis?

• Look at the production process capacity of PCB assembly companies

• Look at the raw material selection of PCB assembly companies

• Look at the production equipment of PCB assembly companies

In a word, in the increasingly competitive market of PCB assembly companies in USA, customers should not blindly pursue low cost, so as to avoid irreparable losses.

SMT PCB assembly companies handling moisture sensors

PCB assembly companies in USA frequently encounter some special components in patch processing, such as MSD, also known as moisture sensitive components, or humidity sensitive components for short, which are a kind of electronic components easily affected by ambient temperature, humidity and static electricity.

PCB assembly companies in USA can standardize the process control method of MSD, so as to avoid the damage of components in the reflow welding process caused by moisture absorption of humidity sensitive components, reduce the resulting product defect rate, and improve the reliability of products.

In PCB assembly companies in USA for MSD be affected with damp be affected with damp, in practical processing are commonly in accordance with the manufacturer of the original packing bag warning labels on the baking conditions for baking. For PCB assembly companies in USA without corresponding requirements, elevated temperature baking is recommended. During the replacement of the MSD carrier, pay attention to preventing ESD damage to the components. Typically, low temperature baking is not recommended for MSD baking.

MSD usage precautions of SMT PCB assembly companies in USA

1. PCB assembly companies in USA's MSD ovens for baking require ventilation and the ability to maintain the required temperature under the condition of humidity less than 5%. 

2. SMT patch components shipped in elevated temperature carriers can be baked at 125℃ unless otherwise stated by PCB assembly companies in USA.

3. PCB assembly companies in USA shall not bake SMT patch components transported in low-temperature carrier at a temperature higher than 40℃. If higher temperature baking is used, the low temperature carrier should be removed and replaced with a high temperature resistant carrier.

4. PCB assembly companies in USA should evacuate the paper or plastic carrier before baking, and the rubber belt or plastic tray should also be evacuated when baking at 125℃.

Maintenance of reflow welder by SMT PCB assembly companies

In order to make the equipment run more efficiently and effectively guarantee the product quality, to introduce the below the PCB assembly companies in USA for reflow soldering equipment maintenance points.

1. Daily maintenance of the reflow welder by PCB assembly companies :

Wash the dust, stains and tin paste on the surface of the furnace body with cloth.

Check the signal tower red, yellow, green light is normal.

Check the transport belt transmission is smooth, vibration, skid.

Whether the set temperature in the temperature area is consistent with the displayed temperature in the display table.

2. PCB assembly companies' weekly maintenance of reflow welder :

Check for loose or worn transport shaft gloves.

Check whether the fixing screws are loose and the air motor is abnormal.

3. Monthly maintenance of reflow welder by PCB assembly companies :

Check coupling parts and bearings for looseness.

Open the exhaust duct to remove foreign matter.

Bearing with extreme temperature lubricating oil.

4. PCB assembly companies' quarterly maintenance of reflux welder :

Wash the floppy disk drive.

5. Annual maintenance of reflow welder by PCB assembly companies :

The part related to power supply must be cut off before maintenance.

After maintenance, it shall be recorded in the reflow maintenance record form.

Solder points for SMT PCB assembly companies

1. PCB assembly companies will closely control the heating temperature and time to avoid extreme temperature damage to additional components.  Typically, the time and temperature of welding is longer than that of welding. 

2. PCB assembly companies staff do not exert too much force when dismantling welding, the component packaging strength decreases under elevated temperature, and the components and pad will be damaged after pulling, shaking and shaking overly frequently.

3. When the employees of PCB assembly companies absorb the solder on the solder joint, they can use the tin suction tool to absorb the solder and pull out the components directly, so as to reduce the welding time and the possibility of damaging the PCB circuit board.

SMT PCB assembly companies desoldering method

1. PCB assembly companies' point-to-point testing method

For horizontal installation of resistance and capacity components, the distance between the two solder joints is distant, can be heated by electric iron point by point, pull out point by point. If the pin is bent, pry it straight with the soldering iron head and then remove it.

2. Centralized diswelding method of PCB assembly companies

Since the pins of the resistor are welded separately, it is difficult to heat them at the same time with an electric iron. You can use a hot air welder to heat several welding points quickly and pull them out once after the solder melts.

3. PCB assembly companies' retention soldering method

A tin suction tool is used to first suck the solder from the removed solder spot, which is normally able to remove the component.

4. PCB assembly companies' cutting and welding method

If there is surplus of the component pins and wires on the dismantled solder joint, or if the components are determined to be damaged, the components or wires can be cut off first, and then the wires on the pad can be removed.

Automated online inspection system from PCB assembly companies

At present, there are mainly AOI system and SPI system for automatic on-line testing of solder paste printing.

1. AOI system of SMT PCB assembly companies.

The automatic optical detection system adopts computer technology, high-speed image processing and recognition technology, with automation, high speed and high resolution detection capabilities, so as to improve the objectivity and accuracy of discrimination, reduce the special fixture, to provide real-time feedback information to the production system of PCB assembly companies. In SMT patch processing, AOI is mainly used for the detection of three processes, one of which is the detection of solder paste after printing.

2. SPI system of SMT PCB assembly companies.

PCB assembly companies solder paste detection system is formed on the basis of AOI technology.  There are two main measurement methods: one is the use of laser triangulation technology, the other is based on the Moire technology. Laser triangulation technology is combined with two-dimensional image to determine the difference between the measurement target height and the standard height. The main disadvantages are low accuracy and insufficient resolution. Because laser triangulation technology has only one light source, it can not accurately calculate the volume of solder paste.

SMT PCB assembly companies advantages

SMT PCB assembly companies' automatic on-line inspection system has two main advantages over the built-in inspection system.

First of all, because the device is a stand-alone system, it can be tested without using the hardware of the printing press and without downtime. Secondly, the measurement performance of the inspection equipment can obtain accurate and repeatable measurement results. SMT PCB assembly companies' automatic online inspection system can choose to use sample inspection, sampling inspection or whole board inspection method depending on the actual production situation. With the emergence of high-speed testing equipment and people's demand for high quality and high reliability of electronic products, the method of automatic online testing of the whole board is mainly used to detect the quality of solder paste printing.

SMT PCB assembly companies wave soldering causes tin beads

Solder spatter may occur on PCB solder surfaces and component surfaces during PCBA wave soldering. Prior to PCBA wave soldering, PCB assembly companies summarized the following conclusions.

1. Manufacturing environment and PCB storage time of PCB assembly companies.

Extreme humidity in PCB assembly companies' manufacturing environment, long time of PCB packaging and opening for SMT and PCBA wave soldering production, or PCBA wave soldering after a period of PCB patch and insertion, may produce tin beads during PCBA wave soldering.

2. PCB resistance welding materials and production quality.

The solder film used in PCB manufacturing is also one of the reasons for tin balls in PCBA wave soldering.

3. SMT PCB assembly companies should choose flux accurately.

There are numerous reasons to solder balls, but flux is the main one.

Advantage of SMT PCB assembly companies in USA

Nowadays, the PCBA processing industry is highly popular. There are PCB assembly companies in most industrial areas, followed by the competition from service to quality, processing capacity and processing cost. The following is a brief introduction to the competitive advantages of PCB assembly companies in USA.

1. Equipment of PCB assembly companies in USA

Excellent equipment is the premise of processing quality and efficiency to be guaranteed.

2. The strength of PCB assembly companies in USA

Only by achieving large-scale production can we effectively reduce procurement and production costs.

3. Technology

PCB assembly companies in USA have a strong overall technical strength.