Jun 26, 2021
Hello guys, today we will walk you through repair tricks for desoldering&soldering of iPhone X charging IC.
First, stick high-temperature tape on components around the charging IC to protect them from pseudo soldering/bridging during the operation.
Then apply some paste flux around the charging IC.
Set temperature of the QUICK 990 AD Vertical Wind Hot Air Gun at 330℃, air flow 3. Keep the hot air gun at 5mm-10mm height from the charging IC. Heat for around 15s-20s, then pry up the charging IC. Tips: control the force applied when prying up the IC. Rough operations might damage the chip or the bonding pad.
Continue to apply some medium-temp solder paste to the bonding pad. Heat with the QUICK 990 AD Vertical Wind Hot Air Gun at 280℃, air flow 3.
Meantime, clean solder joints on the bonding pad with Soldering Iron at 360℃. Once done, clean the pad thoroughly with rosin soaked solder wick. Also, be careful with your operation here. Rough operations might result in pseudo soldering/bridging of components around
Clean with PCB Cleaner afterward.
Now we need to clean solder joints on the backside of the charging IC. Apply some medium-temp solder paste to the bonding pad on the backside. Clean the pad with Soldering Iron at 360℃.
Also, you can apply some paste flux for better cleaning. Once done, clean with PCB Cleaner. Tips: don't be too strict with solder joints on the pad. You can keep several solder joints for the sake of perfect reballing afterwards.
Let's move on to the reballing process. Get the BGA Reballing Stencil in position. Apply some medium-temp solder paste with BGA Scraper.
Then apply the solder paste to a facial tissue. This is to dry the solder paste by wrapping in the facial tissue.
So that the solder paste can be well prepared for reballing. Wettish solder paste might result in bridging during reballing. Continue to smear medium-temp solder paste evenly on the stencil. Wipe out needless solder paste with lint-free wiping cloth. Apply pressure to the BGA Reballing Stencil with tweezers. Heat with the QUICK 990 AD Vertical Wind Hot Air Gun at 300℃, air flow 3. So that all solder balls can solidify completely. Tips: when heating, the hot air gun should approach from far to near from edges to the center.
Concentrated heating might get the stencil deformed. The shaping-up process of solder balls might also be affected. Once done, cool for 1 minute. Clean with PCB Cleaner afterwards. Separate the chip from the stencil with tweezers gently. Then clamp the chip with tweezers.
Heat again with the QUICK 990 AD Vertical Wind Hot Air Gun at 300℃, air flow 3. This is to ensure the perfect formation of solder balls.
Now we can solder the charging IC. Apply some paste flux to the bonding pad.
Get the charging IC in the right position. Do not place it in the wrong direction. Solder with the QUICK 990 AD Vertical Wind Hot Air Gun at 330℃, air flow 2. 15s-20s later, with the IC sinking and paste flux overflowing.
Continue heating for like 5 seconds. Once done, clean with PCB Cleaner.
Feel free to visit REWA Academy to study more phone repair techniques and skills.
Apr 23, 2021
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