MLCC Material Selection Notes for Dashcam (Car DVR) Applications

A dashcam works in a very special environment. It may stay inside a parked car under strong sunlight, and it also works with vibration, sudden power events, and long recording time. Because of these conditions, MLCC (Multi-Layer Ceramic Capacitor) selection is important for product stability and reliability. In this article, I will share practical material selection notes for MLCCs used in dashcam PCBs, especially about X7R, X7S, and X5R.

 

1) Understand What X7R / X7S / X5R Really Mean

 

The “X7R / X7S / X5R” code mainly describes capacitance change versus temperature.

 

• X7R: −55°C to +125°C, capacitance change within ±15%
• X7S: −55°C to +125°C, capacitance change within ±22%
• X5R: −55°C to +85°C, capacitance change within ±15%

Important: This code is about temperature range and capacitance tolerance. It does NOT directly describe DC bias behavior, vibration, or lifetime. Also, if a dashcam PCB uses some X5R parts, it does not mean the whole board will stay below 85°C. It only means the MLCC manufacturer guarantees the temperature specification up to 85°C for those capacitors.

 

2) Temperature Risk in Dashcam: Local Hot Spots

 

In a dashcam, the whole PCB temperature is not uniform. Usually, there are local hot areas near: 

 

• SoC / CPU
• DC/DC converter (buck regulator)
• Wi-Fi module
• memory (DDR, NAND)
• power protection area

So even if the system “ambient” is not very high, local spots can be hotter. That is why engineers should not decide material only by “room temperature”. A good practice is to check hot spots by thermal camera or thermocouple in worst conditions: high ambient, full load recording, charging, Wi-Fi on.

 

3) DC Bias Effect: Real Capacitance Can Drop a Lot 

 

For Class II MLCC (X7R/X7S/X5R), DC bias is a key topic. When DC voltage is applied, the effective capacitance decreases. The drop depends on: 

 

• dielectric formulation
• case size (0201/0402/0603)
• rated voltage (6.3V / 10V / 16V / 25V…)
• structure (layer thickness, number of layers)
• manufacturer series

 

A common mistake is: “0.1 µF means always 0.1 µF.” In reality, a 0.1 µF MLCC might become 0.06 µF or lower under DC bias, especially for very small sizes like 0201.

 

For your example: 0.1 µF, 16V, X7R, 0201 used on dashcam:

 

• For 1.2V/1.8V/3.3V rails, 16V rating gives good margin, so DC bias drop is usually better than using 6.3V parts.
• But 0201 is still very small, so you should ask supplier for Capacitance vs DC Bias curve.

 

4) X7R vs X7S vs X5R: How to Choose in Dashcam

 

When to use X7R

 

Use X7R when you need:

 

• better temperature stability (up to 125°C)
• more stable capacitance for sensitive rails (PLL, analog, sensor power)
• better confidence for hot spots

 

When X7S is OK

 

X7S has a wider temperature capacitance change (±22%), but still works up to 125°C. It may allow:

 

• higher capacitance in same size
• lower cost
• better availability
  For many decoupling positions, X7S is acceptable if you check DC bias curves.

 

When X5R is acceptable

 

X5R is very common and cost-effective. It is often used for:

 

• non-hot areas
• general decoupling
• places where capacitance variation is not critical

But if X5R is placed near hot spot or near power devices, you must be careful. Above 85°C, capacitance change is not guaranteed.

 

5) Mechanical Reliability: Cracking and Vibration

 

Dashcam has vibration and assembly stress. MLCC can crack due to:

 

• PCB bending
• mechanical shock
• thermal cycling (hot/cold changes)

For small size (0201/0402), cracking risk still exists. For better robustness, consider:

 

• Soft termination / flexible termination option
• good PCB layout (avoid placing MLCC across board cut lines, connectors, screw holes)
• keep enough distance from PCB edges
• use proper pad design recommended by supplier

If your dashcam is close to automotive conditions, it is good to ask for AEC-Q200 grade parts (even if not strictly required).

 

6) Placement Strategy: Decoupling is More Than One Capacitor

 

For power integrity, do not rely on only one 0.1 µF:

 

• Place 0.1 µF very close to IC power pin (high frequency decoupling)
• Add 1 µF to 10 µF nearby for mid/low frequency energy
• For sensitive analog or clock rails, sometimes add 0.01 µF as extra high-frequency bypass

 

Decoupling performance depends strongly on:

 

• loop area (short trace, short return path)
• ground quality
• via placement
• ESL/ESR of the capacitor and its mounting

 

7) What to Request From MLCC Supplier

 

To reduce risk, please ask supplier for:

 

1. Capacitance vs DC Bias curve (same size, same voltage rating)
2. Capacitance vs temperature curve
3. Termination type (standard or soft termination)
4. Reliability and failure rate data (if available)
5. Recommended land pattern / soldering notes

 

Conclusion

 

For dashcam MLCC selection, the best approach is not only looking at “X7R/X5R” code. You should consider temperature hot spots, DC bias drop, mechanical stress, and placement. In general, X7R or X7S is safer near hot areas. X5R can be used in cooler areas or for cost down if performance margin is enough. Always check real effective capacitance and request curves from the supplier. This will help you build a stable and reliable dashcam product.

 

#MLCC, #X7R, #X7S, #X5R, #dashcam, #Car #DVR, temperature range, hot spot, DC bias, effective capacitance, decoupling, bypass capacitor, 0201, 16V, soft termination, flexible termination, PCB bending, cracking, thermal cycling, AEC-Q200, power integrity, ESR, ESL, capacitance vs voltage curve, capacitance vs temperature curve.

 

UF capacitors produce reliable MLCC to replace tier-1 brands.

Following some MLCC PIN to PIN alternative to replace Murata/TDK/Vishay etc for dashcam.

 

No	UF capacitors Part Number	UF capacitors Description	Murata P/N#
1	0603G226M250CR	22uF 25V X5S +/-20% 0603 T&R RoHS	#GRM188C61E226ME01D
2	0805X106K500CR	10uF 50V X5R +/-10% 0805 T&R RoHS	#GRM21BR61H106KE43L
3	0603X475K350CR	4.7uF 35V X5R +/-10% 0603 T&R RoHS	#GRM188R6YA475KE15D
4	0402X106M100CR	10uF 10V X5R +/-20% 0402 T&R RoHS	#GRM155R61A106ME11D
5	0402X475M100CR	4.7uF 10V X5R +/-20% 0402 T&R RoHS	#GRT155R61A475ME13D
6	0402B105K100CR	1uF 10V X7R +/-10% 0402 T&R RoHS	#GCM155C71A105KE38D
7	0402B104K500CR	0.1uF 50V X7R +/-10% 0402 T&R RoHS	#GCM155R71H104KE02J
8	0402X106M100CR	10uF 10V X5R +/-20% 0402 T&R RoHS	#GRM155R61A106ME11D
9	0402X105K250CR	1uF 25V X5R +/-10% 0402 T&R RoHS	#GRM155R61E105KA12D