# Component Package Size Recommendations

This guide provides recommended package sizes for all components in the Midea AC Controller PCB design.

## General Recommendations

**For Hand Assembly (Prototyping):**
- Use **0805** (2.0mm × 1.25mm) or larger for passive components
- Easier to solder manually
- Better for low-volume production

**For Automated Assembly (Production):**
- Use **0603** (1.6mm × 0.8mm) or **0402** (1.0mm × 0.5mm)
- Smaller board size
- Lower cost in volume
- Requires pick-and-place machine

**Recommended for this project:** **0805** (good balance of size, cost, and ease of assembly)

---

## Capacitors

### Power Supply Capacitors (C1, C2: 10µF)

| Component | Value | Recommended Package | Alternative | Notes |
|-----------|-------|---------------------|-------------|-------|
| C1, C2 | 10µF | **0805** (2.0×1.25mm) | 0603, 1206 | Ceramic, X7R or X5R, 16V or higher |
| | | **Footprint:** `Capacitor_SMD:C_0805_2012Metric` | | |

**Part Number Examples:**
- **0805:** CL21A106KAYNNNE (Samsung), GRM21BR71C106KE15L (Murata)
- **0603:** CL10B106KB8NNNC (Samsung) - smaller but harder to hand solder
- **1206:** CL31A106KAHNNNE (Samsung) - larger, easier to hand solder

**Voltage Rating:** 16V minimum (for 5V input with margin)

---

### Decoupling Capacitors (C3, C4, C5-C13: 100nF)

| Component | Value | Recommended Package | Alternative | Notes |
|-----------|-------|---------------------|-------------|-------|
| C3, C4, C5-C13 | 100nF (0.1µF) | **0805** (2.0×1.25mm) | 0603, 0402 | Ceramic, X7R, 16V or higher |
| | | **Footprint:** `Capacitor_SMD:C_0805_2012Metric` | | |

**Part Number Examples:**
- **0805:** CL21B104KBCNNNC (Samsung), GRM21BR71H104KA01L (Murata)
- **0603:** CL10B104KA8NNNC (Samsung)
- **0402:** CL05B104KA5NNNC (Samsung) - very small, difficult to hand solder

**Voltage Rating:** 16V minimum

**Recommendation:** Use **0805** for all decoupling capacitors - standard size, easy to source, good for hand assembly.

---

## Resistors

### LED Current Limiting Resistors (R1, R2: 220Ω)

| Component | Value | Recommended Package | Alternative | Notes |
|-----------|-------|---------------------|-------------|-------|
| R1, R2 | 220Ω | **0805** (2.0×1.25mm) | 0603, 1206 | 1/8W or 1/10W rating |
| | | **Footprint:** `Resistor_SMD:R_0805_2012Metric` | | |

**Part Number Examples:**
- **0805:** RC0805FR-07220RL (Yageo), ERJ-6GEYJ221V (Panasonic)
- **0603:** RC0603FR-07220RL (Yageo)
- **1206:** RC1206FR-07220RL (Yageo) - larger, easier to hand solder

**Power Rating:** 1/8W (0.125W) or 1/10W (0.1W) is sufficient
- At 3.3V: P = V²/R = 3.3²/220 = 0.049W (well within rating)

**Tolerance:** ±5% (E24 series) or ±1% (E96 series)

---

### Pull-up Resistors (R3, R4, R5, R6: 10kΩ)

| Component | Value | Recommended Package | Alternative | Notes |
|-----------|-------|---------------------|-------------|-------|
| R3, R4, R5, R6 | 10kΩ | **0805** (2.0×1.25mm) | 0603, 1206 | 1/8W or 1/10W rating |
| | | **Footprint:** `Resistor_SMD:R_0805_2012Metric` | | |

**Part Number Examples:**
- **0805:** RC0805FR-0710KL (Yageo), ERJ-6GEYJ103V (Panasonic)
- **0603:** RC0603FR-0710KL (Yageo)
- **1206:** RC1206FR-0710KL (Yageo)

**Power Rating:** 1/8W (0.125W) or 1/10W (0.1W) is sufficient
- At 3.3V: P = V²/R = 3.3²/10000 = 0.001W (very low power)

**Tolerance:** ±5% (E24 series) is sufficient for pull-ups

---

## LEDs

| Component | Type | Recommended Package | Alternative | Notes |
|-----------|------|---------------------|-------------|-------|
| LED1, LED2 | LED | **0805** (2.0×1.25mm) | 0603, 1206 | Red or Green, 20mA forward current |
| | | **Footprint:** `LED_SMD:LED_0805_2012Metric` | | |

**Part Number Examples:**
- **0805:** 
  - Red: LTST-C170KFKT (Lite-On), L-7113HD (Kingbright)
  - Green: LTST-C170KGKT (Lite-On), L-7113GD (Kingbright)
- **0603:** Smaller, harder to see and hand solder
- **1206:** Larger, brighter, easier to see

**Specifications:**
- Forward Voltage: 2.0-2.2V (Red), 3.0-3.2V (Green)
- Forward Current: 20mA typical
- With 220Ω resistor at 3.3V: I = (3.3V - 2.0V) / 220Ω = 5.9mA (safe, visible)

**Recommendation:** Use **0805** - good visibility, easy to solder, standard size.

---

## Buttons (Switches)

| Component | Type | Recommended Package | Alternative | Notes |
|-----------|------|---------------------|-------------|-------|
| SW1, SW2 | Tactile Switch | **6×6mm** | 4×4mm, 12×12mm | Through-hole or SMD |
| | | **Footprint:** `Button_Switch_SMD:SW_SPST_Tactile_6.0x6.0mm` | | |

**Part Number Examples:**
- **6×6mm SMD:** B3SN-3112P (Omron), KMR2 (C&K)
- **6×6mm THT:** B3F-4055 (Omron), KMR2 (C&K)
- **4×4mm:** Smaller, harder to press
- **12×12mm:** Larger, easier to press

**Specifications:**
- Actuation Force: 2.55N (260gf) typical
- Travel: 0.25mm typical
- Life: 100,000+ cycles

**Recommendation:** Use **6×6mm** - good size for finger pressing, common footprint.

---

## Voltage Regulator (U1: AMS1117-3.3)

| Component | Type | Package | Footprint | Notes |
|-----------|------|--------|-----------|-------|
| U1 | AMS1117-3.3 | **SOT-223** | `Package_TO_SOT_SMD:SOT-223` | 1A LDO regulator |

**Package Dimensions:**
- Body: 6.5mm × 3.5mm
- Height: 1.6mm
- Lead pitch: 2.3mm

**Part Number Examples:**
- AMS1117-3.3 (Advanced Monolithic Systems)
- LM1117-3.3 (Texas Instruments) - pin-compatible alternative

**Thermal Considerations:**
- Maximum power dissipation: ~1W (depends on heatsinking)
- At 5V input, 3.3V output, 500mA: P = (5-3.3) × 0.5 = 0.85W
- The large tab helps with heat dissipation

**Recommendation:** SOT-223 is standard and appropriate for this application.

---

## Level Shifter (U3: TXB0104PWR)

| Component | Type | Package | Footprint | Notes |
|-----------|------|--------|-----------|-------|
| U3 | TXB0104PWR | **TSSOP-14** | `Package_SO:TSSOP-14_4.4x5mm_P0.65mm` | 4-channel level shifter |

**Package Dimensions:**
- Body: 5.0mm × 4.4mm
- Height: 1.2mm
- Lead pitch: 0.65mm (fine pitch)

**Part Number:**
- TXB0104PWR (Texas Instruments)

**Assembly Note:**
- Fine pitch (0.65mm) requires careful soldering
- Consider using hot air rework station or reflow oven
- Can be hand soldered with fine tip and flux

**Recommendation:** TSSOP-14 is the standard package for this part.

---

## ESP32 Module (U2: ESP32-WROOM-32E)

| Component | Type | Package | Footprint | Notes |
|-----------|------|--------|-----------|-------|
| U2 | ESP32-WROOM-32E | **38-pin QFN** | Custom footprint required | ESP32 module |

**Package Dimensions:**
- Body: 18mm × 25.5mm × 3.1mm
- Pin pitch: 1.27mm (0.05")
- 38 pins total

**Footprint:**
- You'll need to create a custom footprint or use an existing ESP32-WROOM footprint
- Common footprint libraries may have this

**Assembly Note:**
- Requires reflow soldering (hot air or reflow oven)
- Can be hand soldered with hot air rework station
- Bottom pad needs to be soldered for proper thermal and electrical connection

**Recommendation:** Use the official Espressif footprint or create custom footprint based on datasheet.

---

## Connectors

### J1: JST-XH Connector (4-pin)

| Component | Type | Package | Footprint | Notes |
|-----------|------|--------|-----------|-------|
| J1 | JST-XH 4-pin | **JST-XH-B4B-XH-A** | `Connector_JST:JST_XH_B4B-XH-A` | 2.5mm pitch |

**Package Dimensions:**
- Pitch: 2.5mm
- Height: ~8mm
- Through-hole mounting

**Part Number:**
- B4B-XH-A (JST) - Female connector (receptacle on PCB)
- Matching cable connector: B4B-XH-A-1 (with cable)

**Recommendation:** Standard JST-XH footprint, through-hole for mechanical strength.

---

### J2: Programming Header (6-pin)

| Component | Type | Package | Footprint | Notes |
|-----------|------|--------|-----------|-------|
| J2 | Pin Header | **2.54mm pitch** | `Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical` | Standard 0.1" pitch |

**Package Dimensions:**
- Pitch: 2.54mm (0.1")
- Height: 8.5mm typical (can vary)
- Through-hole mounting

**Part Number Examples:**
- Generic pin headers available from many manufacturers
- Can use straight or right-angle headers
- Consider using shrouded header for keyed connection

**Recommendation:** Standard 2.54mm pitch header - very common, easy to source.

---

## Summary Table

| Component Type | Recommended Package | Size | Assembly Difficulty |
|----------------|---------------------|------|---------------------|
| **Capacitors (10µF)** | 0805 | 2.0×1.25mm | Easy |
| **Capacitors (100nF)** | 0805 | 2.0×1.25mm | Easy |
| **Resistors (all)** | 0805 | 2.0×1.25mm | Easy |
| **LEDs** | 0805 | 2.0×1.25mm | Easy |
| **Buttons** | 6×6mm | 6×6mm | Easy |
| **AMS1117-3.3** | SOT-223 | 6.5×3.5mm | Medium |
| **TXB0104PWR** | TSSOP-14 | 5.0×4.4mm | Medium (fine pitch) |
| **ESP32-WROOM-32E** | QFN-38 | 18×25.5mm | Hard (requires reflow) |
| **JST-XH Connector** | Through-hole | 2.5mm pitch | Easy |
| **Programming Header** | Through-hole | 2.54mm pitch | Easy |

---

## Manufacturing Considerations

### For Hand Assembly (Prototyping):
- Use **0805** for all passives (capacitors, resistors)
- Use **through-hole** connectors where possible
- Use **6×6mm** buttons
- ESP32 may require hot air rework station

### For Automated Assembly (Production):
- Can use **0603** or **0402** for passives (smaller, cheaper)
- All SMD components work with pick-and-place
- Reduces board size
- Lower cost in volume

### Recommended for This Project:
- **0805** for all passive components - good balance
- Standard through-hole connectors
- Standard SMD packages for ICs

---

## KiCad Footprint Library References

When assigning footprints in KiCad, use these library paths:

- **Capacitors (0805):** `Capacitor_SMD:C_0805_2012Metric`
- **Resistors (0805):** `Resistor_SMD:R_0805_2012Metric`
- **LEDs (0805):** `LED_SMD:LED_0805_2012Metric`
- **Buttons (6×6mm):** `Button_Switch_SMD:SW_SPST_Tactile_6.0x6.0mm`
- **AMS1117-3.3:** `Package_TO_SOT_SMD:SOT-223`
- **TXB0104PWR:** `Package_SO:TSSOP-14_4.4x5mm_P0.65mm`
- **JST-XH:** `Connector_JST:JST_XH_B4B-XH-A`
- **Programming Header:** `Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical`

---

## Cost Considerations

**Package Size vs Cost (typical, per 1000 units):**
- **0402:** Lowest cost, smallest size
- **0603:** Low cost, small size
- **0805:** Moderate cost, good size (recommended)
- **1206:** Higher cost, larger size

**For this project:** 0805 is the sweet spot - not too expensive, not too hard to assemble.

---

## Availability

All recommended packages are:
- **Widely available** from major distributors (Digi-Key, Mouser, LCSC, etc.)
- **Standard sizes** used across the industry
- **Well-documented** with datasheets and application notes
- **Compatible** with standard PCB manufacturing processes


