Panasonic KX-TG7341UAM / KX-TG7341UAT / KX-TGA731RUM / KX-TGA731RUT / KX-TGA731RUC / KX-TGA731RUS Service Manual ▷ View online
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12.3. How to Replace the Flat Package IC
Even if you do not have the special tools (for example, a spot heater) to remove the Flat IC, with some solder (large amount), a
soldering iron and a cutter knife, you can easily remove the ICs that have more than 100 pins.
soldering iron and a cutter knife, you can easily remove the ICs that have more than 100 pins.
12.3.1. Preparation
• PbF (: Pb free) Solder
• Soldering Iron
• Soldering Iron
Tip Temperature of 700
°F ± 20 °F (370 °C ± 10 °C)
Note: We recommend a 30 to 40 Watt soldering iron. An expert may be able to use a 60 to 80 Watt iron where someone with
less experience could overheat and damage the PCB foil.
less experience could overheat and damage the PCB foil.
• Flux
Recommended Flux: Specific Gravity
→ 0.82.
Type
→ RMA (lower residue, non-cleaning type)
Note: See About Lead Free Solder (Pbf: Pb free) (P.4)
12.3.2. How to Remove the IC
1. Put plenty of solder on the IC pins so that the pins can be completely covered.
Note:
If the IC pins are not soldered enough, you may give pressure to the P.C. board when cutting the pins with a cutter.
2. Make a few cuts into the joint (between the IC and its pins) first and then cut off the pins thoroughly.
3. While the solder melts, remove it together with the IC pins.
When you attach a new IC to the board, remove all solder left on the board with some tools like a soldering wire. If some solder is
left at the joint on the board, the new IC will not be attached properly.
left at the joint on the board, the new IC will not be attached properly.
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12.3.3. How to Install the IC
1. Temporarily fix the FLAT PACKAGE IC, soldering the two marked pins.
*Check the accuracy of the IC setting with the corresponding soldering foil.
2. Apply flux to all pins of the FLAT PACKAGE IC.
3. Solder the pins, sliding the soldering iron in the direction of the arrow.
12.3.4. How to Remove a Solder Bridge
1. Lightly resolder the bridged portion.
2. Remove the remaining solder along the pins using a soldering iron as shown in the figure below.
2. Remove the remaining solder along the pins using a soldering iron as shown in the figure below.
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12.4. How to Replace the LLP (Leadless Leadframe Package) IC
12.4.1. Preparation
• PbF (: Pb free) Solder
• Soldering Iron
• Soldering Iron
Tip Temperature of 700
°F ± 20°F (370°C ± 10°C)
Note:
We recommend a 30 to 40 Watt soldering iron. An expert may be able to use a 60 to 80 Watt iron where someone with less
experience could overheat and damage the PCB foil.
We recommend a 30 to 40 Watt soldering iron. An expert may be able to use a 60 to 80 Watt iron where someone with less
experience could overheat and damage the PCB foil.
• Hot Air Desoldering Tool
Temperature: 608
°F ± 68°F (320°C ± 20°C)
12.4.2. Caution
• To replace the IC efficiently, choose the right sized nozzle of the hot air desoldering tool that matches the IC package.
• Be careful about the temperature of the hot air desoldering tool not to damage the PCB and/or IC.
• Be careful about the temperature of the hot air desoldering tool not to damage the PCB and/or IC.
12.4.3. How to Remove the IC
1. Heat the IC with a hot air desoldering tool through the P.C.Board.
2. Pick up the IC with tweezers, etc. when the solder is melted completely.
Note:
• Be careful not to touch the peripheral parts with tweezers, etc. They are unstable.
When it is hard to melt the solder completely, heat it with a hot air desoldering tool through the IC besides through the
P.C.Board.
P.C.Board.
3. After removing the IC, clean the P.C.Board of residual solder.
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12.4.4. How to Install the IC
1. Place the solder a little on the land where the radiation GND pad on IC bottom is to be attached.
2. Place the solder a little on the land where IC pins are to be attached, then place the IC.
Note:
• When placing the IC, the positioning should be done very carefully.
3. Heat the IC with a hot air desoldering tool through the P.C.Board until the solder on IC bottom is melted.
Note:
• Be sure to place it precisely, controlling the air volume of the hot air desoldering tool.
4. After soldering, confirm there are no short and open circuits with visual inspection.
12.4.5. How to Remove a Solder Bridge
When a Solder Bridge is found after soldering the bottom of the IC, remove it with a soldering iron.
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