DC Micro Resistance Welding

DC Resistance spot welding joins metal pieces together by applying pressure and passing a large current through a localized area.

A DC welding system uses a Direct Current Waveform. This allows for a rapid upslope, a sustained peak, and a rapid downslope. This waveform is similar to a square, with a sharp increase in energy at the trigger, flat constant peak energy, then a sharp decrease in energy to finish. This allows for very fine control, especially on the lower end of the energy settings.

Why Use DC Welding?

DC welding is perfect for very small and fine wire welding. DC Power supplies have the ability to control the weld current very low & precise. One of the major applications for the DC Welding systems is Thermal Compression Welding. DC welding is also very useful in PCB repair, and trace welding. Additionally, DC welding is used anytime a very small wire, is being welded.

What is Thermal Compression Welding?

Thermal Compression Welding uses a DC Welding system, with a Thermal Compression Electrode. These electrodes have a very fine tip, that is bonded. This tip is specifically designed to heat up and transfer heat to the workpiece. Pressure is applied downward to the joint, and as energy is passed through the TCB Electrode. The tip of the electrode heats up, and with the pressure applied creates a weld. This process is primarily used in welding magnet and very fine wire welding. The tip heat will melt through the magnet wire coating and create a metal to metal weld.

What is needed in a DC Welding system?

Power Supply:

Sunstone offers 2 different DC Welding Power supplies. The Sunstone Linear DC, and The Avio Linear DC.

The Sunstone Linear DC Features an 8″ touchscreen display. This allows you to adjust your settings easily and quickly. This also gives you a graphic output of your weld waveform. Giving you the ability to see graphically what your weld will look like.

Weld Head or Hand-Piece?

With a DC Welding system, there are 3 major weld delivery options.

Weld Head:

The Sunstone WH2125A & The WH1125A are both options for delivery of DC welds. These are both Pneumatically controlled and allow you to adjust the pressure to perfectly fit your application. These are not the most popular options, due to the size of most DC welding projects. Depending on your application and access to your welding parts, as well as the amount of force that can be applied to your parts.

Micro-Weld Head:

The most popular option for delivering DC welds is a Micro-Weld head. These have very fine control over the pressure being applied and allow you to adjust this pressure in a matter of grams. This ultra fine control allows the user to adjust the pressure to fit any application. These weld heads are both pneumatically, servo, and manual foot pedal control. The Sunstone Micro Weld-Head has a foot pedal that manually moves the weld head down for extra precision. This weld head also uses the Thermal Compression Electrodes, to complete thermal compression welds. This weld head holds the electrode and applies force to complete these types of welds. The Sunstone Micro-Weld head also includes a free-floating arm Mounted microscope that allows you to see the very small wires that you are welding.

Hand Attachment:

The last option to deliver DC Welds is through the use of a Hand Attachment. These can vary in function and form. Hand Attachments vary from simple welding probes to tweezers, and pressure actuated hand-pieces. The most popular hand attachment used with DC welding systems is the Dual Probe Hand Piece- Micro (DPHP-Micro). This hand-piece allows you to deliver Thermal Compression Welds by hand. This is the only Hand Attachments that uses the TCB electrode.

What Thermal Compression Electrodes Are Available?

The various TCB electrodes have a specific function to help you get the desired weld.

• TCB-FL – Most Common TCB Electrode – used for all-purpose welds. The flat tip allows for an even weld.
• TCB- SMFL – Similar to the FL, but with a 25% Smaller tip surface.
• TCB-2525T – Has the smallest tip of any TCB electrode at .010″ square- flat tip for even welding.
• TCB-SY – 5-degree slant side to side. This allows for the electrode to weld with deeper penetration on one side.
• TCB-SL – Designed to weld and cut a wire, the SL has 7-degree tip angle from front to back. To cut the wire at the front, and weld at the back.
• TCB-U – The most robust TCB Tip – Used for higher power/ higher heat applications, thicker magnet wires, or in high production applications.