Thermocompression welding or its basic concepts

Thermocompression This metal joining method is a type of cold pressure welding with heating of either the tool or the workpiece. Although heating can be combined, both the workpiece and the tool are heated simultaneously. The set temperature is constant throughout the process and is below the eutectic temperature of the materials being joined. The pressure on the parts is low, but sufficient for metal diffusion. Thermocompression The method includes three heating methods:

• 1. Special heater;
• 2. Heating with a welding tool;
• 3. A wire through which a current pulse passes at the point of contact;

The welded conductor is deformed only after heating.

Thermocompression welding temperatures and materials

Thermocompression welding The welding tool connects highly conductive materials, both flat and round, with thin conductive films deposited on dielectric substrates. The end of the tool has a correspondingly shaped head made of hard metals: tungsten, carbide, steel, and sapphire. The resulting joint is quite strong, high-quality, and has good electrical conductivity. This is also facilitated by the cleanliness of the wire and substrate. The welding principle is simple:

• — the punch, which has a hard tip, is heated by a heat source to 300 degrees, the table is heated to 450 degrees, if necessary;
• — with a reciprocating motion presses the wire to the surface of the semiconductor;
• — under pressure, to facilitate shear deformation, transverse ultrasonic vibrations are created;
• — compression time up to 2 seconds.

Thermocompression welding It is widely used in electronics and microelectronics. In this field, this type of welding allows for the preservation of all the properties of conductors without affecting their electrical conductivity. Thermal compression is used to join gold and germanium, gold and silicon, and aluminum and silver. The disadvantages of this type of welding include:

• — relative strength of the welded wire;
• — difficulty in automating the process;
• - thoroughness of checking the welding process itself.

Advantages:

• — the possibility of welding soft materials;
• — durability of the welding tool;
• - easy to control the process;
• - no need for solders and fluxes.

Thermocompression welding machine

Thermocompression welding machine This allows for high-quality process technology with various wire and substrate thicknesses. Some brands of such units include "Kontakt-1A," "EM-422," "EM422A," and "EM-439A." These models feature worktable heating temperatures ranging from 100°C to 500°C. The UMS-1TK unit is designed for overlapping thin wires up to 50 µm in diameter, ensuring high-quality connections without burning. Thermocompression welding machine "AVIO", "AVIO PHU-35TW" is designed for soldering and mounting printed circuit boards, heating temperature is 600 0C, has a set of heads with different values.

Thermocompression soldering

Thermocompression soldering It's performed using the same equipment as thermocompression welding. The difference lies in the amount of power supplied to the tool tip. For soldering, it's less powerful and requires solder. Thermocompression soldering Involves heating flux-coated parts coated with solder to the solder's melting point and flow rate. Only the soldered joint area is heated. The soldering technology is the same as welding and is well suited for heat-sensitive and light-sensitive components. Thermocompression soldering It is produced on flexible printed circuit boards, which are used in a variety of electronic products in automotive equipment, cell phones, digital cameras, calculators, etc.