What is the difference between SMD crystal oscillator and DIP crystal oscillator?

Is the crystal SMD oscillator interchangeable with the DIP crystal oscillator?

Generally speaking, crystal SMD and DIP crystal are welded in different ways. If the electrical parameters and space allow, it can be interchanged. 

In terms of specific crystal oscillator application requirements, there are significant differences between them.

First of all, the welding method, which is the most obvious difference between them. The DIP crystal oscillator needs manual welding, which is often accompanied by the leg cutting process, because the pins of the crystal oscillator need to be inserted through the PCB board. The thickness of PCB varies with the design. Generally, the length of straight crystal oscillator pin is 3mm after leg cutting. It is easy to cause physical mechanical damage or damage to the crystal oscillator in the process of leg cutting, to cause some bad crystal oscillator in varying degrees. In the process of manual welding, if the operator's welding technology is not up to standard, it is easy to cause solder paste adhesion or poor temperature control of soldering iron, resulting in poor quality crystal oscillator. In addition, the active DIP crystal oscillator is easy to be destroyed by electrostatic breakdown. And the crystal SMD oscillator tape can meet the reflow soldering automatic chip placement, greatly reducing the degree of human damage to the crystal oscillator.

As far as the volume is concerned, crystal SMD oscillator has tended to miniaturization and low power consumption with small load. Most DIP crystal oscillators are 49S and cylinder. Although 49S derives small, bottom shell and other categories, and cylinder also has 1 * 5, crystal SMD oscillators with smaller sizes, such as 2520 and 2016, have been widely used, especially in portable digital products, such as Bluetooth and smart watches.

DIP crystal oscillator has a price advantage. With the rapid improvement of SMT crystal oscillator manufacturing technology, the price gap is getting smaller and smaller.

On the interchangeability between crystal SMD oscillator and DIP crystal oscillator: Under the condition that the electrical parameters of crystal oscillator are completely consistent and the PCB space is satisfied, the interchangeability can be realized. For example, 49SMD 12Mhz, 20pF 20ppm, frequency stability 30ppm (- 20 ~ + 70), resistance less than 30 Ω, can be interchanged with the same electrical parameters crystal SMD oscillator.

In the case of small PCB, it is impossible to achieve interchangeability. 

For example, SMD2016 or SMD2520 used in TWS Bluetooth headset can not be replaced by 49S, because the volume of a 49S crystal is close to that of a TWS Bluetooth headset. Moreover, it is impossible to put a 49S in the children's smart watch. The height alone can not meet the demand.

The DIP crystal oscillator is generally used for civil consumer electronic products. Some of them are used for factory automation equipment and civil consumer electronics, such as computer and TV motherboard, inverter, network telephone, etc. The cylinder used to be used in some camera schemes, but now it tends to be replaced by SMT crystal oscillator. 

At present, crystal SMD oscillator can also have wide temperature characteristics to meet the harsh temperature environment.

Most active crystal oscillators are crystal SMD oscillators, such as TCXO, VCXO, VC-TCXO, etc., which are commonly used in base stations, high-speed data transmission devices, Bluetooth, WiFi, 5G, etc.