How to choose the package of resistance and capacitor
? Are there any principles? For example, the same 104 capacitor has 0603, 0805 packages, and the same 10uF capacitor has 3216, 0805, 3528 packages, etc. Which package is more suitable?
The resistor-capacitor package is commonly used in the circuit I have seen:
The possible packages of 0.01uF are 0603, 0805
10uF packages are 3216, 3528, 0805
100uF has 7343
320pF package: 0603 or 0805
4.7K, 10k, 330, 33 are available in 0603 and 0805 packages.
So how to choose these packages?
The package of SMD mainly includes: 0201 1/20W 0402 1/16W 0603 1/10W 0805 1/8W 1206 1/4W
The corresponding relationship between the capacitor and resistor dimensions and the package is: 0402=1.0x0.5 0603=1.6x0.8 0805=2.0x1.2 1206=3.2x1.6 1210=3.2x2.5 1812=4.5x3.2 2225=5.6 x6.5
The size of the capacitor itself has nothing to do with the package form, and the package is related to the nominal power. Its length and width are generally expressed in millimeters. However, the model number is expressed in inches.
Choosing the right package first depends on your PCB space, whether you can put this device down. Generally speaking, a device with a large package will be cheaper, and a device with a small package may be more expensive because of the higher processing speed. Then the withstand voltage value of a large packaged capacitor will be higher than that of a small packaged capacitor with the same capacity. These are all selected according to your actual needs. In addition, small package components have higher requirements for placement, such as the accuracy of SMT machines. For example, the circuit board in a mobile phone has limited space and low operating voltage, so you can choose 0402 resistors and capacitors, and large-capacity tantalum capacitors are mostly 3216 and other large packages.
For hardware engineers, they are dealing with various components every day. The most common components are probably resistors and capacitors.
The packaging of resistors and capacitors (PCB Footprint) is generally represented by numbers such as 0603 and 0805 after R or C.
If I ask you the package is C0805 what is the resistance size? You must know that the size of the capacitor is about 2.0mm×1.2mm. Even if you don't remember the number of this size, you probably know how big the capacitor is in your impression.
Let's find a capacitor (from Yageo
) to see this parameter:
The two rows represent the size information of capacitors with thicknesses of 0.85mm and 1.25mm, respectively.
This kind of package representation is the most commonly used. However, sometimes we will see two completely different representations for the same component. For example, we open the Mentor Graphics IPC-7351 LP Wizard software, and then find the capacitor. There are two ways to see the package of the same capacitor:
Take the device CAPC2013X100N as an example. In the description, you can see that its size is 2.0mm×1.25mm, but in the column Standard Name, which is the package name, there are two package names, one is EIA 0805 and the other It is Metric 2013. So what exactly do these two packages mean, and which one should we use as our package name?
In fact, EIA and Metric are two different size code methods. EIA is the code of the American Electronics Industry Association. 08 and 05 in 0805 represent the length and width of the resistance or capacitance respectively, and the unit is English. The length and width of the 0805 capacitor we saw above are metric units of 2mm and 1.25mm, corresponding to 0.078inches and 0.049incheses in English system, rounded to the nearest two digits are 0.08inches and 0.05inches. This is why his EIA code is 0805. Reading the text is not intuitive enough, we look at the following table:
This can be seen more intuitively. What we usually use is the package size indicated by EIA Code. There is also a more detailed table below (the table comes from Microfarads; the orange-yellow mark indicates some of our most commonly used packages):
The above concepts about packaging and size are clarified. When selecting models, we will not make low-level mistakes such as using wrong resistors and capacitors.