Is your iPhone X constantly crashing whenever you open apps—even after a restore? You’re not alone. This issue is often linked to a deeper hardware fault, especially if you’re seeing iTunes restore error 1100. While software problems are a common culprit, in this case, the cause is more likely poor CPU soldering on the motherboard.
In this comprehensive repair guide, we’ll walk you through how to diagnose and resolve iPhone X app crashing problems by resoldering the CPU upper layer and properly reassembling the motherboard. Whether you’re a repair technician, DIY enthusiast, or run a repair shop, this guide offers actionable steps to bring the iPhone X back to life.
Model Overview
Model: iPhone X
Announced: 2017, September 12
Issue: Apps keep crashing after restore; iTunes reports error 1100
Defect Analysis: iPhone X Apps Crashing Issue
A customer brought in an iPhone X with persistent app crashing problems. Despite performing a full system restore just days before, the issue remained. We initially suspected a software glitch but ruled it out after another restore attempt via iTunes resulted in error 1100.
🔍 What’s Error 1100?
Error 1100 typically indicates a hardware communication failure, often related to the CPU or NAND soldering quality. In this case, the CPU’s upper layer connection was the root cause.
Repair Process: iPhone X CPU Resoldering & Motherboard Recombination
Here’s a breakdown of the hands-on repair process performed by REWA technicians:
Step 1: Attempt Restore via iTunes
- Restored the device using iTunes → Error 1100 appeared
- Diagnosis: Potential CPU upper layer soldering issue
Step 2: Remove the CPU Upper Layer
Tools used: Hot air gun, sculpture knife
- Gently heat the CPU using a hot air gun
- Carefully pry the upper layer off the chip with a sculpture knife
⚠️ Caution: Do not overheat. Avoid damaging the lower CPU layer.
Step 3: Clean the Tin Pads
- Remove residual glue using cleaning solvent
- Ensure all solder pads are clean and evenly exposed
Step 4: Solder the CPU Upper Layer Back
Tools used: Solder flux, tweezers, hot air gun
- Apply solder flux to the CPU pad area
- Align the upper layer with the lower layer using tweezers
- Heat gently with a hot air gun and slightly press the chip
- If the chip re-seats perfectly, soldering is successful
Step 5: Reassemble the Motherboard
Tools used: Heating platform
- Align both layers of the motherboard using tweezers
- Set heating platform temperature to 130°C
- Start heating. Continue for 1 additional minute once the motherboard sinks and solder flux flows out
Step 6: Final Testing
- Reassemble the phone
- Power it on and test:
✅ Apps launch normally
✅ All functions work as expected
Tools & Parts Used
- Hot air gun
- Sculpture knife
- Solder flux
- Tweezers
- Cleaning solution (for glue removal)
- Heating platform
- iTunes (for initial software restore)
Technical Terms
- Sculpture knife: A precision tool used to lift components or remove glue without damaging the PCB.
- Solder flux: A chemical agent that helps solder flow smoothly and prevents oxidation during soldering.
- Tin pads: The contact areas on the motherboard or CPU where solder connects components.
- Heating platform: A temperature-controlled base used to heat the motherboard evenly for soldering or reflow work.
- Motherboard recombination: Reassembling a split-layered motherboard (common in iPhone logic boards) using controlled heat and alignment.
Conclusion: Mastering iPhone X App Crash Repairs
Fixing the iPhone X apps crashing issue—especially those tied to iTunes error 1100—often goes beyond software troubleshooting. As this case demonstrated, poor soldering between CPU layers can disrupt app stability. By mastering CPU resoldering and motherboard recombination, you can restore functionality and save devices that might otherwise be considered irreparable.
Want to perfect your soldering skills? Join the REWA Academy’s iPhone Motherboard Repair Course for in-depth, hands-on training.
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