Beijing Welder Technology Co., Ltd

 

Abstract: Metal packaging is used in various integrated circuits, microwave devices, luminous devices and other products, and has a wide range of applications. This article lists the various package types in the field of metal packaging and briefly introduces the characteristics of each package; and the welding principle and welding process of metal packaging.

 

Because metal has good mechanical strength, good thermal conductivity and electromagnetic shielding function and easy machining, metal packaging has outstanding reliability under the harshest conditions of use, so it is widely used in military and civilian fields. Generally, according to the division of packaging materials, metal packaging is divided into pure copper, alloy, and cermet integrated packaging; According to the different components of the package, the metal package includes at least TO package, BOX package, butterfly package, SMD package, large module metal package, passive crystal oscillator package, etc., which are common component packages.

1 TO package

The TO package is a typical metal package. The TO package has excellent performance with high speed and high thermal conductivity. For high-speed devices in optical communications, transmission rates of more than 25Gbit/s can be achieved using metal TO housing packages; For electronics or modules that require high heat dissipation efficiency, better heat dissipation can be achieved using high thermal conductivity TO housing packages, which uses oxygen-free copper instead of traditional KAVA alloy at a thermal conductivity rate of more than 10 times that of conventional housings. Common TO specifications are TO-18, TO-46, TO-56, TO-8, TO-9, TO-10, etc., as shown in Figure 1 for a variety of specifications and models of TO components.

 

Figure 1 Example of a TO shell

 

 

The packaging of the above types of TO components can be packaged by energy storage sealing and welding machine, such as the FHJ-3 automatic energy storage sealing and welding machine produced by Beijing Kexin Institute of Electromechanical Technology (hereinafter referred to as Beijing Kexin). Energy storage sealing and welding machine, its working principle is mainly to use a certain charging circuit to charge the capacitor, by the capacitor first store the energy, when the stored energy reaches the energy value that can melt the welding joint of the contact surface of the welded device, the control system controls the instantaneous discharge of the capacitor, providing concentrated energy to the welding area, so as to obtain weldments with good surface quality and small deformation.

 

2 BOX package

BOX package is a form of packaging of high-power semiconductor devices, usually consisting of multiple in-line devices on a silicon substrate and fixed on a thermally conductive medium by finale or SMD. An example of a large-size BOX package shown in Figure 2.

 

Figure 2BOXPackage Example

 

For BOX packaging components, FHJ-2 energy storage sealing and welding machine produced by Beijing Kexin can be used for packaging, which belongs to single-station capacitor energy storage resistance sealing and welding machine, and the welding current waveform has a wide adjustment range, which can meet the welding needs of different materials and workpieces of different sizes.

 

3 Butterfly package

Butterfly package in the appearance of the shell is usually cuboid, which contains double in-line pins, the structure and implementation of the function is usually more complex, can be built-in cooler, heat sink, ceramic substrate, chip, thermistor, backlight monitoring, and can support all the above components of the bonding lead, The large surface area of the package enables good heat dissipation and makes it suitable for various rates of transmission and long-distance transmission up to 80km. Example of a butterfly package in various sizes as shown in Figure 3.

Figure 3: Example of a butterfly package

 

 

For butterfly package components, GHJ-4 single-head parallel soldering machine or GHJ-5 large module parallel rolling welding machine can be used for packaging, and the specific type of welder used for packaging needs to be selected according to the butterfly package size.

 

4 SMD package

SMD packaging is the most commonly used form of packaging in surface mount technology (SMT), which is the direct attachment of components to the surface of a printed circuit board. SMD package has the characteristics of small size, light weight, excellent performance and automatic production, and is suitable for high-density integrated circuits such as communications, computers, and automotive electronics. Examples of SMD packages in several sizes are shown in Figure 4.

Figure 4 Example of SMD package

 

For some small SMD components, in order to prevent the relative displacement of the base and cover plate during the packaging process, they can be packaged by pre-soldering and then roll soldering. For example, using the YHJ-1 pre-welding machine of Beijing Kexin shown in Figure 5, the high-precision positioning function of the vision system is used for positioning and spot welding to achieve the fixation of the device cover plate and the base, so as to prevent the relative displacement of the base and the cover plate during the packaging process; Finally, the GHJ-1 parallel soldering machine shown in Figure 6 is used to complete the final package.

Figure5 YHJ-1pre-welding machine

Figure 6 Double-head parallel rolling welding machine

 

 

5 modules in metal package

Large module metal packaging is usually used in special occasions such as high power, high voltage, high current, etc., and has the characteristics of good heat dissipation performance, stable structure, safety and reliability. The gradual popularization and application of large module metal packaging provides reliable technical support for industrial automation and energy saving. Figure 7 shows two large modules in metal packages.

 

Figure 7 Large module metal package

 

 

Large module metal encapsulation welding equipment, can use GHJ-5 large module parallel rolling welding machine, the glove box of the machine is equipped with vacuum baking rich room, the setting temperature of the heating plate can reach 180 degrees Celsius, using double heating plate heating method; The baking vacuum is kept in the range of 20-50Pa; It is suitable for the packaging of flat metal shell seats with side length 5~300mm and the butterfly packaging of optoelectronic devices, which can store the relevant parameters of different components and realize one-click switching.

 

6 Passive crystal oscillator package

Common passive crystal oscillator packages include HC-49U (49U), HC-49S (49S), UM series, etc., as shown in Figure 8. 49U, 49S, UM series are now several products widely used in quartz crystal oscillators, because of their low cost, precision, stability and other civil electronic equipment, so they are favored by factories.

Figure 8 49U, 49S, UM series

 

Take HC-49S as an example, 49S is also known as HC-49US package. HC-49S belongs to in-line quartz crystal oscillator package, in-line 2 pins, high shell volume of 10.5×4.5×3.5MM, short shell volume of 10.5×5.0×2.5MM, is an international common standard, common parameter standard load capacitance is 20PF (12PF 16PF 30PF, etc.) The accuracy is ±20PPM±50ppm, etc., the resistance is 120Ω, and the parameter standards are no different from HC-49U and HC-49SMD. 49S is smaller than 49U, which will not waste board space due to large size, and will not increase the cost of circuit boards, and has gradually replaced 49U.

For the packaging of passive crystal oscillators, generally use FHJ-1A or FHJ-1B for packaging, for aerospace and other situations with very high requirements for use conditions, FHJ-1D high vacuum automatic energy storage sealing and welding machine can be used for sealing and welding, so that the device can reach a higher vacuum degree inside.

The various welding equipment used in the packaging of the various components introduced above is welded using resistance welding technology. Resistance welding is generally a method of applying a certain pressure to the welded workpiece, using the workpiece as a load resistance, supplying power to the workpiece through the upper and lower electrodes, and using the Joule heat generated by the current through the workpiece to melt the contact surface between the two workpieces to achieve the contact surface welding method of the two workpieces.

The packaging process of the above components basically includes the following steps:

(1) Preparation stage: prepare the components to be welded and the corresponding welding equipment, and place the components on the carrier plate;

(2) Component placement: the two workpieces of the welded can be placed on the upper electrode and lower electrode of the welding equipment in an automatic way by means of nozzle parts;

(3) Welding: make the surface of the two workpieces to be welded in contact, when the energy can melt the small area of the welding joint, the welding equipment carries out instantaneous discharge of capacitance, that is, the two workpieces are discharged through the upper and lower electrodes, so that the molten liquid metal fills the welding surface;

(4) Cooling: After the soldering process is completed, the components are cooled to room temperature, forming excellent solder joints in the welding area, so as to achieve the purpose of packaging the components.

It should be noted that parameters such as voltage, capacitance, and air pressure are adjusted according to specific needs; In the sealing and welding process between the cap and the header of the component, or between the cover plate and the base, attention should be paid to controlling the welding temperature and time, maintaining environmental hygiene and operating specifications, which will help improve the quality and stability of the product.

The welding process of resistance welding technology does not require the addition of flux and welding wire, does not produce waste gas, and is more environmentally friendly than traditional welding methods; And the welding process does not produce welding slag, and the welding surface is clean and beautiful.

In summary, the metal packaging forms are diverse, the processing is flexible, and the selection and process methods of packaging components are determined according to the needs, which not only meet the functional requirements, but also consider the cost and advanced technology. With the continuous advancement of science and technology, the types and process methods of metal packaging will continue to be updated and expanded.