✅ 1. Why Your Reballing Success Rate Drops

✔ Underfill residue on edges
✔ Poor preheating
✔ Wrong solder paste alloy
✔ Uneven stencil pressure
✔ CPU warping due to fast heat
✔ Overheating (kills PMIC/SoC instantly)
✔ Board not fully preheated
✔ Bad flux (burns or carbon forms)
✔ No microscope alignment
✔ Using cheap stencil

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✅ 2. Best Equipment for High Success Rate (Recommended by Industry)

A) Preheater (MUST-HAVE for modern CPU reballing)

A bottom preheater makes 70% difference.

✔ Scotle IR6000 / IR-PRO-600
✔ Quick 853A++
✔ LY IR900 / IR6500
✔ TBK 928 / Sunshine S918 (mobile CPU specific)

Why?
It heats the board from bottom evenly (150–180°C), preventing warpage and giving smooth reflow.

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B) Hot Air Station

Best results with:

✔ Quick 861DW – stable airflow, accurate temp
✔ Quick 2008
✔ BEST 863
✔ Jovy RE-8500 (advanced)

For MTK & Qualcomm:
Airflow: Medium (30–35%)
Temp: ~330–350°C (after preheat)

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C) Stencil (High accuracy)

Use 0.12mm or 0.13mm A8 steel stencils.

Best brands:
✔ ReballingPro
✔ Mechanic Solder Masks
✔ Qianli 3D Stencil
✔ Relife High-Temp Stencil

Avoid cheap soft stencils.

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D) Flux (Only use these)

✔ AMTECH NC-559-ASM (Original)
✔ Relife RL-404
✔ Mechanic UV893 (for MTK recommended)
✔ MECHANIC XG-Z40 paste for balling

Cheap flux burns and causes CPU bend.

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E) Cleaning Tools

✔ High-quality IPA 99%
✔ Kapton tape
✔ Ultrasonic cleaner (optional but increases success rate)
✔ Scalpel blades #11
✔ Fiberglass cleaning pen
✔ Soft brass brush
✔ Microfiber cloth + polishing plate

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✅ 3. Step-by-Step Professional Reballing Method

STEP 1 — Remove Underfill (MOST CRITICAL STEP)

Qualcomm & MTK CPUs have strong underfill around edges.

Best safe technique:

✔ Preheat board: 160–180°C for 2–3 mins
✔ Use sharp blade at 45° angle
✔ Slice underfill slowly without touching pads
✔ Use micro hot air 290°C air 20% to soften edges

Do NOT overheat — CPUs crack internally.

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STEP 2 — CPU Removal

After underfill loosens:

Preheat 160–180°C for 2–3 mins
Hot air: 350°C, air 35%
Time: 45–70 sec depending on CPU size

Check floating test
– When CPU starts sliding on flux, remove gently.

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STEP 3 — Pad Cleaning (Very Important)

Goal: Make pads flat, shiny, and perfectly even.

Method:

✔ Add flux
✔ Use low temp 320°C, air 20%
✔ Sweep pads sideways with knife OR copper wick
✔ Do not press hard → avoids pad lifting
✔ Clean again with IPA + brush

Pads must appear golden and smooth, not scratched.

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STEP 4 — Stencil Alignment & Balling

Best technique:

✔ Use thick framed stencil for MTK/Qualcomm
✔ Fix CPU with Kapton tape
✔ Apply Minimal flux (do NOT flood)
✔ Apply solder paste evenly
✔ Heat from top of stencil:
350°C, air 20–25%
✔ Balls will form in 8–12 seconds

After cooling:
Clean with IPA.

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STEP 5 — CPU Reflow on Board

Preheat is mandatory

✔ 150–160°C for 2 minutes

Reinstalling

✔ Align under microscope
✔ Add light flux
✔ Hot air: 350°C, 30% air
✔ Time: 40–55 sec
CPU should
➡ auto-align
➡ sit down by itself
➡ center perfectly

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STEP 6 — Post Cleaning

✔ Clean around edges with IPA 99%
✔ Check short on CPU A, B, C power lines
✔ Test boot with DC

Expected reading:
Qualcomm idle: 0.06–0.15A before screen
MTK idle: 0.05–0.12A before logo

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✅ 4. Increase Success Rate (Pro Tips)

✔ Preheat always

Boards are multi-layer; without preheat they warp and kill CPU.

✔ Use high-quality stencil

Smooth holes = round balls = perfect alignment.

✔ Don’t use too much flux

Causes floating issues and misalignment.

✔ Keep CPU flat on metal plate

Prevents warping during cooling.

✔ Use the right solder alloy

63/37 SnPb preferred
Better flow, lower temp, protects CPU.

✔ Use microscope for alignment

Without microscope success rate is 50%.

✔ Keep airflow medium

Too high = blows balls away
Too low = incomplete melting

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✅ 5. Success Rate If You Follow These

Situation	Success Rate
No preheater + cheap stencil	40–55%
Preheater + good stencil	70–80%
Preheater + thick stencil + good flux	90–95%
Complete professional method above	95–98% success

✅ Why 63/37 SnPb Solder Is Preferred for Reballing CPU

63% Tin + 37% Lead
This is the only alloy that becomes a true eutectic solder.

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🔥 1. EUTECTIC POINT (Very Important)

63/37 melts and solidifies at one exact temperature:

👉 Melting point: 183°C
👉 No plastic/semi-melt phase

This means:
✔ It melts instantly
✔ It hardens instantly
✔ Zero “mushy” stage
✔ Balls form perfectly round
✔ No bridging
✔ Pads don’t lift
✔ CPU doesn’t overheat

Other alloys (lead-free or mixed) enter plastic phase = balls deform = CPU misalignment.

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🔥 2. Lower Temperature = Safer CPU

Modern Qualcomm / MediaTek SoC dies are ultra sensitive.

Typical hot air temps:

Alloy	Required heat
63/37 SnPb	330–350°C
Lead-free SAC305	360–390°C
Cheap Chinese “mix” paste	380–410°C

Higher temperature = higher risk of:

❌ CPU internal crack
❌ Baseband damage
❌ PMIC thermal stress
❌ PCB pad lifting
❌ CPU warping

63/37 keeps the work temperature lower, reducing stress on the CPU and motherboard.

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🔥 3. Better Wetting / Better Flow

63/37 SnPb spreads perfectly on pads:

✔ Smooth wetting
✔ Perfect round balls
✔ No half-melt issues
✔ No poor connection
✔ No cold joints

This alone increases reball success rate 30–40%.

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🔥 4. Strong Joints + Flex Absorption

Mobile motherboards bend slightly during use.

63/37 solder has natural flexibility → absorbs vibration.

Lead-free solder is harder → cracks after reflow, causes:

❌ Random restarts
❌ Network issues
❌ Dead after a few days
❌ Heat when pressing CPU area

This is why many repaired phones die later—wrong solder.

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🔥 5. Safe for 90% Components (eMMC / UFS / PMIC)

63/37 works perfectly with:

✔ CPU / SoC
✔ Baseband
✔ PMIC
✔ eMMC
✔ UFS
✔ Charging IC
✔ RF ICs

Safe temperature window is wide, very technician-friendly.

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🔥 6. Very Predictable Flow Behavior

This alloy has:

✔ Fixed melt temp
✔ No delayed reflow
✔ Consistent movement
✔ Perfect auto-alignment

When the balls melt, CPU auto-centers perfectly.

This is why professional reballers love 63/37.

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🔥 7. Long Lifespan Joints

63/37 joints survive:

✔ Heat cycles
✔ Board flex
✔ Daily temperature variations
✔ Drops
✔ Long-term usage

Lead-free joints crack faster.

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🔥 8. Easy for Beginners + Experts

Even medium-skilled technicians get:

✔ 80–90% success
✔ Smooth flow
✔ Very forgiving process

If using lead-free → success rate 50% or less.

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📌 Recommended Pastes (Original Only)

Use only these for best results:

⭐ Best solder paste for reballing

✔ MECHANIC XG-Z40 (63/37)
✔ AMTECH NC-559-ASM + solder balls 0.35–0.45mm
✔ RELIFE RL-402 / RL-403 SnPb
✔ Qianli Sn63/Pb37

Avoid cheap pastes like RG-100, JF-X or unknown brands—they melt inconsistently.

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📌 When to Use Lead-Free

Only when the device originally has:

⬅ iPhone motherboards (some models)
⬅ Certain Wi-Fi ICs
⬅ Some RF front-end modules

But for Android CPU Reballing (Qualcomm / MTK)
→ Always use Sn63/Pb37 for highest success rate.

✅ 1) QUALCOMM CPU FULL TEMPERATURE MAP

⭐ Snapdragon 632 / 636 / 660 / 665 / 675

CPU Removal

• Preheat (Bottom heater): 160–180°C (2–3 min)
• Hot Air: 350–360°C
• Airflow: 30–35%
• Time: 55–75 sec
• Behaviour: Flux boils → CPU floats → remove

Pad Cleaning

• 320°C, air 20%
• Light swipe, no pressure

Reballing

• Stencil heat: 350°C, air 20–25%
• Balls form 8–12 sec

Reinstallation

• Preheat: 150–160°C
• Hot air: 350°C, air 30%
• Time: 40–55 sec
• Behaviour: CPU auto-aligns, sinks down

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⭐ Snapdragon 720G / 730G / 732G

CPU Removal

• Preheat: 170–180°C
• Hot air: 355–365°C
• Airflow: 32%
• Time: 65–80 sec

Reballing

• Stencil: 350°C
• Air: 20–22%

Reinstall

• 350°C, 30% air for 45–60 sec

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⭐ Snapdragon 750G / 765G / 778G

These CPUs have more layers + stronger underfill.

CPU Removal

• Preheat: 180°C
• Hot air: 360–370°C
• Airflow: 33–38%
• Time: 75–95 sec
• Behaviour: Edge underfill must soften first!

Reballing

• Stencil: 350–360°C
• Air: 20%

Reinstall

• 350–360°C, 30% air, 50–70 sec

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⭐ Snapdragon 8-Series (835 / 845 / 855 / 865)

Most sensitive to warping — preheat is mandatory.

CPU Removal

• Preheat: 180–190°C
• Hot air: 360–370°C
• Air: 35%
• Time: 80–110 sec

Reballing

• 350°C @ 20%

Reinstall

• 355°C @ 30% air

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✅ 2) MEDIATEK CPU FULL TEMPERATURE MAP

⭐ Helio G25 / G35 / G36

Removal

• Preheat: 160–170°C
• Hot air: 345–355°C
• Air: 30–32%
• Time: 55–70 sec

Reballing

• 345°C (MTK balls melt faster)
• Air: 20%

Reinstall

• 345–350°C, 30% air

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⭐ Helio G70 / G80 / G85

Removal

• Preheat: 170°C
• Hot air: 350–360°C
• Air: 32%
• Time: 60–85 sec

Reballing

• 350°C, 20% air

Reinstall

• 350°C, 30% air, 45–60 sec

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⭐ Helio P60 / P70 / P90

Removal

• Preheat: 170–180°C
• Hot air: 360°C
• Air: 32–36%
• Time: 75–95 sec

Reballing

• 350°C

Reinstall

• 350–360°C

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✅ 3) eMMC IC TEMPERATURE MAP

Removal

• Preheat: 150–160°C
• Hot air: 340–350°C
• Air: 28–32%
• Time: 30–50 sec

Reballing

• Stencil: 330–340°C
• Air: 18–20%
• Time: 8–10 sec

Reinstall

• 335–345°C @ 28–30% air

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✅ 4) UFS IC TEMPERATURE MAP

⚠ UFS is more sensitive than eMMC.

Removal

• Preheat: 160–170°C
• Hot air: 345–355°C
• Air: 28–32%
• Time: 35–55 sec

Reballing

• 335–345°C
• Air: 18–20%
• Balls form in 6–8 seconds

Reinstall

• 345°C @ 30% air

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✅ 5) PMIC / Power IC TEMPERATURE MAP

Removal

• Preheat: 150–160°C
• Hot air: 340–350°C
• Air: 25–30%
• Time: 20–40 sec

Reinstall

• 335–345°C
• Air 25–28%

⚠ PMIC overheating = instant dead phone
Always use preheat to avoid board bending.

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🔥 IMPORTANT FIXED RULES FOR ALL ICs

✔ Use Sn63/Pb37 ALWAYS

→ lower temp, safer reflow, cleaner balls.

✔ Preheat mandatory

→ protects CPU from internal cracks.

✔ Use small amount of flux

→ too much causes floating/misalignment.

✔ Airflow medium

→ high airflow = blown balls
→ low airflow = incomplete melt

🟦 1) HEAT PROFILE DIAGRAMS (ASCII GRAPH – Easy to understand)

⭐ A) Mobile CPU Removal – Heat Curve

Temp (°C)
380 |                           ████
360 |                        ████  ███
340 |                     ███        ███
320 |                  ███             ███
300 |               ███                  ███
280 |            ███                        ███
260 |         ███                              ███
240 |      ███                                    ███
220 |   ███                                          ███
200 |████ Preheat Stage (Board at 160–180°C)           ███
    ----------------------------------------------------------> Time
         0s     20s     40s     60s     80s     100s

STAGES:
- 0–30 sec → FLUX ACTIVATION  
- 30–60 sec → UNDERFILL SOFTENS  
- 60–90 sec → CPU FLOATS → REMOVE

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⭐ B) CPU REBALLING (Stencil Heating Curve)

360 |                       █████████
340 |                    ███        ███
320 |                 ███              ███
300 |              ███                    ███
280 |           ███                          ███
260 |        ███                                ███
    -------------------------------------------------> Time (10–15 sec)

STAGES:
- 0–5 sec   → Flux thinning  
- 5–10 sec → Paste liquifies  
- 10–12 sec → Balls form round  
- 12–15 sec → Stop heating!

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⭐ C) CPU RE-INSTALLATION HEAT CURVE

360 |                    ████████
340 |                 ███        ███
320 |              ███             ███
300 |           ███                  ███
280 |        ███                        ███
    ---------------------------------------------------> Time (40–60 sec)

STAGES:
- 0–15 sec  → Balls warming  
- 15–35 sec → Alignment & surface tension  
- 35–55 sec → CPU settles & sinks  
- 55+ sec  → REMOVE heat (do not overcook)

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🟧 2) UNDERFILL REMOVAL MAP (TOP VIEW)

⭐ Qualcomm / MTK CPU Underfill Zones

  +------------------------------------------------+
  | ######### ############### ########### ######## |
  | # HARD # #   MEDIUM     # # MEDIUM # # HARD #  |
  | ######### ############### ########### ######## |
  |                                                |
  | ######### ############### ########### ######## |
  | # HARD # #   SOFT       # # SOFT   # # HARD #  |
  | ######### ############### ########### ######## |
  +------------------------------------------------+

LEGEND

• HARD ZONES (Dark) → Corners
  → Scrape very slowly at 45°
• MEDIUM → sides
  → Medium heat (290–310°C)
• SOFT (Easy) → center edges
  → Softens early → safe removal

Best Method

✔ Preheat 160–180°C
✔ Use blade angle 45°
✔ Heat 290–310°C, air 20%
✔ Move blade gently → don’t cut pads

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🟩 3) CPU REBALLING WORKFLOW POSTER (Professional)

===========================================================
        🔧 MOBILE CPU REBALLING WORKFLOW – PRO VERSION
===========================================================

1. BOARD PREHEAT
   - 160–180°C for 2–3 minutes
   - Prevents warping & internal CPU damage

2. UNDERFILL REMOVAL
   - 290–310°C, low air
   - 45° blade angle
   - Clean edges fully

3. CPU REMOVAL
   - 350–370°C, air 30–35%
   - Remove when CPU floats

4. PAD CLEANING
   - 320°C, air 18–20%
   - Use wick or knife gently
   - Pads must be flat & shiny

5. STENCIL ALIGNMENT
   - Fix CPU with tape
   - Use thick steel stencil (0.12–0.13mm)

6. BALLING
   - Apply minimal flux
   - Heat stencil top: 350°C, air 20%
   - Balls form in 8–12 sec

7. CPU INSPECTION (MICROSCOPE)
   - Balls round?
   - No bridges?

8. RE-INSTALLATION
   - Board preheat: 150–160°C
   - Hot air: 350°C, 30% air
   - CPU auto-aligns & sinks

9. CLEANING
   - IPA 99% + brush
   - Check short

10. TEST ON DC SUPPLY
    Qualcomm idle: 0.06–0.15A
    MTK idle: 0.05–0.12A
===========================================================

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🟨 4) CPU BALL SIZE CHART (Qualcomm / MediaTek)

CPU Model	Ball Size
Snapdragon 430 / 435	0.35mm
Snapdragon 450 / 625 / 626	0.35mm
Snapdragon 632 / 636	0.35mm
Snapdragon 660 / 665	0.40mm
Snapdragon 675	0.40mm
Snapdragon 720G / 730G	0.40mm
Snapdragon 750G / 765G	0.40mm
Snapdragon 778G	0.40mm
Snapdragon 845	0.40mm
Snapdragon 855 / 865	0.40mm
MTK Helio G25 / G35	0.35mm
MTK G70 / G80 / G85	0.40mm
MTK P60 / P70	0.40mm

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🟫 5) AIRFLOW % CHART (Quick 861DW / 2008 / BEST 863)

⭐ Quick 861DW Airflow Chart

Air %	Strength	Use Case
20%	Very Low	Stencil reballing
25%	Low	Small ICs
30%	Medium	CPU install
35%	Medium-High	CPU removal
40%+	High	Not recommended (blows balls)

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⭐ Quick 2008

Air %	Use
20–25%	Stencil balling
28–32%	CPU installation
35–38%	CPU removal

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⭐ BEST 863

Air %	Use
18–22%	Balling
25–30%	Install
32–36%	Removal