What are the sizes of disposable patch fuses packaged?

This is an article about the size packaging of disposable patch fuses (such as "patch fuse size", "SMD fuse packaging", "fuse selection", "0402 fuse", "1206 fuse", etc.).
 
Detailed explanation and selection guide for common sizes and packaging of disposable patch fuses
 
In the pursuit of miniaturization and high integration in modern electronic device design, patch fuses have become an ideal choice for circuit overcurrent protection due to their small size, easy installation, and reliable performance. Among them, disposable surface mount fuses (also known as SMD fuses) are the most widely used. Understanding its standard size packaging is crucial for circuit board (PCB) layout design, component selection, and cost control. This article will systematically introduce the mainstream packaging specifications, characteristics, and application scenarios of disposable patch fuses, and briefly explain their packaging density considerations in PCB design (about 6%).
 
List of mainstream disposable patch fuse size packaging
 
The packaging size of patch fuses usually follows the internationally recognized EIA (Electronic Industries Alliance) standard, which uses a four digit code to represent their length and width (in 0.01 inches). Meanwhile, metric size codes (in millimeters) are also widely used. The following are the most common packaging sizes for disposable patch fuses on the market:
 
0402 (metric: 1005)
Dimensions: Length 1.00 mm (± 0.10 mm) x Width 0.50 mm (± 0.10 mm) x Height 0.30 mm (± 0.10 mm) or 0.50 mm (± 0.10 mm) (common).
Feature: It is currently one of the smallest size patch fuses that can be mass-produced. Extremely compact in size, suitable for ultra small portable devices with extremely limited space and high component density (such as TWS earphones, smartwatches, miniature sensor modules, and high-end mobile phone interiors).
Typical rated current range: usually low, commonly ranging from 0.5A to 1A or 1.5A.
Voltage range: commonly 32V DC or 63V DC.
 
Selection precautions: Welding and rework require high process precision; The ability to break is usually relatively small; The heat dissipation capacity is limited, and careful calculation of working current and pulse tolerance is required.
 
0603 (metric: 1608)
Dimensions: Length 1.60 mm (± 0.15 mm) x Width 0.80 mm (± 0.15 mm) x Height 0.60 mm (± 0.15 mm) or 0.80 mm (± 0.15 mm) (common).
Features: It is currently the most widely used, cost-effective, and supplied standard patch fuse size. A good balance has been achieved between volume and performance.
Typical rated current range: wide coverage, commonly ranging from 0.125A, 0.25A, 0.5A, 0.75A, 1A, 1.25A, 1.5A, 2A, 2.5A, 3A, 3.5A, 4A, 5A (depending on the manufacturer and series).
 
Voltage range: commonly 32V DC, 63V DC, 125V DC.
Application scenarios: Smartphones, tablets, laptops, digital cameras, routers, consumer electronics motherboards, various power modules, etc. It is the preferred choice for universal design.
 
3. 1206 (metric: 3216)
Dimensions: 3.20 mm in length (± 0.20 mm) x 1.60 mm in width (± 0.20 mm) x 0.60 mm in height (± 0.20 mm) or 1.10 mm (± 0.20 mm) (common).
 
Features: Relatively large volume, providing higher rated current, higher breaking capacity, and better heat dissipation performance. Mechanical strength is also superior to smaller packaging.
 
Typical rated current range: commonly 0.5A, 1A, 1.5A, 2A, 2.5A, 3A, 3.5A, 4A, 5A, 6A, 7A, 8A, 10A, or even higher (depending on the series).
Voltage range: commonly 32V DC, 63V DC, 125V DC, some series can reach 250V AC/DC.
Application scenarios: In situations where large currents need to be carried or high breaking capacity is required, such as power input/output terminals, adapters, industrial control boards, automotive electronics (non engine compartment), LED drivers, small and medium power motor control, etc.
 
4. Other sizes (relatively rare)
 
03015 (metric: 0804): smaller than 0402, not yet widely produced and applied, mainly used for cutting-edge miniaturized equipment.
 
0805 (metric: 2012): Once an early standard, it is gradually being replaced by 0603 and 1206, but still used in some old designs or specific current requirements.
1210 (metric: 3225): Size greater than 1206, used for higher currents (such as 10A or above) or special requirements.
1812 (metric: 4532)/2920 (metric: 7343): Belonging to larger sizes, typically used for very high currents (such as 15A, 20A, 30A or even higher) or applications that require extremely high breaking capacity (such as some industrial power supplies, UPS, electric vehicle related equipment). At this point, they may be closer to the size of power devices.
 
The relationship between packaging size and electrical parameters
 
Rated current: Generally speaking, the larger the package size, the higher the rated current it can carry (due to its larger melt cross-sectional area and better heat dissipation).
Rated voltage: Fuses with larger sizes are usually able to support higher rated voltages.
Breaking ability: Large size packaging usually has higher breaking ability, which can safely cut off larger fault currents.
Fusing characteristics (fast break/slow break): Both fast break and slow break characteristics are widely used in mainstream packaging sizes (0402, 0603, 1206), depending on the internal structure and materials of the fuse, and have no absolute binding relationship with the size itself.
 
PCB packaging density considerations (approximately 6%)
 
When evaluating the impact of patch fuses on PCB space, "packaging density" is a key indicator. The term 'about 6%' here is an empirical reference value, which refers to:
 
1. Proportion of component area: In the local area where the fuse layout is considered (such as the power input area), the area occupied by the solder pads and body of the patch fuse itself accounts for about 6% of the total PCB area in that area. This is a relative concept, not the average density of the entire board.
 
2. Influencing factors: