SMT maintenance detailed steps and operational essentials

- Sep 28, 2019-

SMT maintenance detailed steps and operational essentials

1. Purpose

Make SMT maintenance personnel familiar with and master all kinds of bad correct maintenance and correct use of each equipment, and improve the quality of maintenance products according to the operation standards.

2. area

Applicable to Shenzhen Ao Yuexin Technology Co., Ltd. SMT repair

3. Duties

3.1, maintenance personnel: responsible for the daily maintenance of defective products and the correct use of equipment, cleaning and maintenance;

3.2, technicians and extension: responsible for the supervision and technical guidance of maintenance quality.

4. Prepare:

4.1. Prepare the tools to confirm that the heat gun is working.

4.2. Understand the type of machine produced by the famous line and the board number used.

5, tools:

Tweezers, thermostatic soldering iron, anti-static brush, hot air gun, waste box, anti-static gloves, roped electrostatic ring, etc.

 6, material description:

6.1 Tin wire

6.1.1 Tin wire specification: strong ¢0.8MM

6.1.2 Tin wire shelf life: 1 year, exposure time: 30 days

6.2 Model of SMD: Fuji NE3000S6.2.1 Maximum operating time after opening the tank: 7 days

6.2.2 Unopened refrigerated storage time: 6 months

6.3 Environmentally friendly washing water

6.3.1 Shelf life: None

6.3.2 Exposure time: none

6.4 Wipe paper

6.4.1 SMT wipe paper

6.5 Rosin, flux

6.5.1 rosin shelf life: 1 year

6.5.2 Rosin exposure time: 7 days

7. Homework:

7.1 For the soldering station temperature test of the repair station, at least once per shift, IPQC fills in the "ironing iron check record form"

7.2 Remove the PCB board to be repaired from the defective product card holder, place it on the maintenance station and check for bad phenomena and bad points.

7.3 Repair the parts that need to be replaced, such as missing parts, body damage, etc.: SOP components

7.4 Component removal

7.4.1 Observe the surface of the PCB board for contamination, oxidation, and foreign matter. If it is, clean it with environmentally friendly wash water and dry it.

7.4.2 Setting the heat gun console temperature to 450 ° C

7.4.3 Apply rib flux to the end of the component with a syringe

7.4.4 When the displayed temperature value reaches the set value, move the hot air gun nozzle to the 5±2MM above the removed component to start heating.

7.4.5 When the heating time reaches the melting of the solder, the components are removed and shaped by tweezers.

7.5 component welding

7.5.1 Prepare the correct components for the point based on the latest product BOM of the component being repaired

7.5.2 Select a constant temperature soldering iron with a knife-shaped soldering iron tip to set the temperature of the console: lead 340±20°C lead-free 380±20°C

7.5.3 Apply ribbed flux to each pad at this point with a syringe

7.5.4 Place the selected OK component with the tweezers and place it on the pad (when clamping the component, the tweezers should be clamped on the side of the component body to avoid the component foot)

7.5.5 Take the tin wire and apply tin to the soldering iron tip and solder the component legs (when the first leg is soldered, the tweezers cannot be removed). After soldering, clean and self-check the SOP component (there are double-row component legs and External application), QFP components (with four columns of components and outward)

7.6 Component removal

7.6.1 Observe the surface of the PCB for contamination, oxidation, foreign matter, and if necessary, clean it with a cleaning agent and dry it. 7.6.2 Set the temperature of the heat gun console to 450 °C.

7.6.3 Apply rib flux to the end of the component with a syringe

7.6.4 When the displayed temperature value reaches the set value, move the hot air gun nozzle to the 5±2MM above the removed component to start heating.

7.6.5 When the heating time reaches the melting of the solder, the components are removed and shaped by tweezers.

7.6.6 Check the condition of the removed components. If there are missing feet, broken feet or bad raw materials, they will be returned to the material handler. Other repair instructions according to the IC repair instructions.

7.7 Component Welding

7.7.1 According to the latest product BOM of the repaired component, prepare the correct component for the point (for components that are trimmed OK, it is preferred)

7.7.2 Select the constant temperature soldering iron of the blade tip and set the temperature of the console: lead 340±20°C lead-free 380±20°C

7.7.3 Apply flux to each pad at this point with a syringe

7.7.4 Take the tin wire, cover the solder wire with the soldering wire, and use a constant temperature soldering iron to heat the tin wire at a 45-degree angle to clean the residual solder on the PCB or directly remove it with a soldering iron.

7.7.5 Place the selected OK component with the tweezers and place it on the pad (when clamping the component, the tweezers should be clamped on the side of the component body to avoid the component foot)

7.7.6 Take the tin wire, apply tin to the soldering iron tip and solder the diagonal component of the component first.

7.7.7 Apply tin to the soldering iron tip, use a soldering iron to attach the component foot and slowly move the soldering iron in one direction of the entire row of component legs until the entire row of components is soldered, and the other component legs are performed in this way. welding

7.8 Rectangular chip components and electrolytic capacitors

7.8.1 Offset component with constant temperature soldering iron with knife tip, console temperature setting: lead 340±20°C lead-free 380±20°C, correct component

7.8.2 For missing parts and bulk rupture elements, add flux to the pads on the pads, use a constant temperature soldering iron with a knife tip and remove the tweezers.

7.8.3 Welding method and welding with SOT components

7.9 Wash the soldering end or component of the component with another antistatic brush and re-examine the soldering condition. If it is found that the solder ball, tin tip, solder joint, unweld, short circuit is corrected with a constant temperature soldering iron

7.10 Repairing components fixed with patch adhesive

7.10.1 According to the BOM specification, the item number and product name specification of the point should be OK. 7.10.2 Observe the surface of the PCB board for stains, oxidation, impurities, and if necessary, wash and dry with washing water.

7.10.3 Remove components directly with tweezers

7.10.4 Immediately check the PCB pad. If there is a patch on the PCB, immediately wipe off the patch with SMT wipe.

7.10.5 Wash the pads and PCB with wash water until there is no residue

7.10.6 Squeeze the fresh patch glue to the original dispensing position with a syringe

7.10.7 Place the selected OK component on the pad with a tweezers

7.10.8 After the parts are placed in OK, the reflow furnace is re-applied within 1 hour.

7.11 The following repairs are made for the positions of the virtual weld, the unweld, and the cold weld:

7.11.1 The syringe is coated with flux on each pad at this point.

7.11.2 Select the constant temperature soldering iron of the blade tip to set the console temperature: lead 340±20°C lead-free 380±20°C

7.11.3 Add the tin wire to the constant temperature soldering iron tip, and then repair the component foot with a soldering iron.

7.12 Repair the points for the short circuit as follows:

7.12.1 Apply flux to each pad at this point with a syringe

7.12.2 Select the constant temperature soldering iron of the blade tip and set the control temperature: lead 340±20°C lead-free 380±20°C

7.12.3 Clean the shorted solder on the shorted component foot with a constant temperature soldering iron tip

7.13 Repairing the OK PCB to make repair marks

7.14 Place the PCB in the card to be inspected and inspect the inspector to check if the part is acceptable according to the standard.

8. Control focus:

8.1 You must have a job permit to operate

8.2 Keep the work area clean

8.3 Do not damage other components when correcting

8.4 The board to be analyzed shall not exceed 24 hours at most.

8.5 Polar components should pay attention to the direction

8.6 Strictly observe the welding process standards

8.7 Insert the plug into the 220V power socket when inserting the soldering iron power supply

8.8 Heat guns must not face others when working, to prevent injury

8.9 After the soldering iron is used, it should be cleaned up in time to prevent the soldering iron from oxidizing.

8.10 Turn off the power supply after using all kinds of instruments.

8.11 See the operation manual for the specific operation steps.

8.12 Move the nozzle to the distance above the removed component and measure with a high temperature fixture

8.13 If there is an abnormality, you should inform the squad leader, supervisor and other relevant personnel.

8.14 Must wear an electrostatic bracelet, wear anti-static clothing and shoes

8.15 After repairing OK, use the adjustment pin to gently dial the IC pin to avoid the IC has a solder joint.

8.16 After the repair is completed, the "Maintenance Record Form" must be recorded for the position of the replacement component.

8.17 It is forbidden to hold the PCB with bare hands during repair, and you must wear static gloves.

8.18 Tools such as soldering iron, tin wire, tin wire, anti-static brush, syringe, waste box for lead-free repair are special for lead-free PCB repair, and should not be used for repair of leaded PCB.

The above is the industry consultation provided by smt patch processing factory Shenzhen Pengzexiang Technology Co., Ltd., I hope to help you! Please contact us if necessary: http://www.oem-pcb.com pcb@sunsoartech.com

 


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