The K&S-4700 Convertible dual wire bonder provides wedge-wedge and ball-ball bonding with the same machine. 90º, deep access bonding is done with a Z-translation of 12.5 mm. The system is equipped with a Nikon SMZ660 optical microscope (0.8-5x zoom), 4 coil tip heating (up to 400 ºC) and at the moment Au, Al and Pt wire is available for bonding. The system is set up in HL614 on the sixth floor. Link to the manual: manual.

• DON't use high powers, power should be in the range of 1 till 2
• DON't leave the system with the wire out of the wedge
• DO write the logbook, any comments are appreciated

Check if the wedge is installed correctly. With the test button on the left panel you can check if the wedge is installed properly in the US transducer. Push the button down, the 'U/S' LED should light up continuously. If bonding doesn't work make sure you check the US transducer again.

1. Mount the workpiece onto the workholder, positioning it in the middle of the workholder. Then push the clamps up by pushing at the sides and then slide it a bit inward so that the workpiece is fixed when the clamps are released.
2. Determine how you will bond the sample; where will the first bond be, and where will the second one go
3. First check that the wedge is correctly mounted: the flat side of the wedge is facing the user and the height is set correctly. The height can be calibrated with the wedge install tool.
4. Check that the wire has been fed through the metal clip, black clamp and wedge correctly.

1. Set Loop Height: 2
2. Remove sample holder, so the bonds are made in air
3. Select 'Semi-Automatic' bonding (right side switch)
4. Press and release left mouse button: this makes a bond in air
5. Now the wedge is at loop height. Adjust work holder such that it fits under the wedge.
6. While looking through the microscope, adjust the work holder height such that the wire is just above the lowest point of the sample
7. Set loop height to a high value so you can easily remove the work holder and make the second bond in air
8. Set 1st and 2nd Search Height to >5
9. Set Loop Height to 4, typical for ~1cm sample, for larger samples you can increase loop height
10. Place work holder back and press and hold left mouse button
11. Set 1st and 2nd search height correctly

With everything setup, you can now start bonding, either in semi-automatic or manual mode. Semi-automatic has the advantage you can controll the search height with the knobs really precisely for every bond.

Finding the right parameters for you process can be a tedious job and requires some work and experience. Just increasing all of these is never the solution! Every application requires it's own 'recipe' of bonding parameters. E.g. bonding Au wire to Cu substrates requires different bonding parameters as compared to bonding Al wire to Au substrates. You can refer to the table below to find a good starting point to set the bonding parameters. When the bonding doesn't work you can either increase Force and Time when the bonds are weak, or decrease Force and Time when the bonds break. When changing the Force and Time doesn't give you good bonds, you can adjust the Power.

Wedge bonding is a uni-directional process, starting the first bond at the front of the sample and making the second bond at the back of the sample (while sitting in front of the machine). When the wire is fed through the wedge and also through the hole at the backside of the wedge correctly (which requires some time or handyness), wedge bonding can start. First make sure that the surplus of wire within a reasonable amount or do a test bond first.

1. Press and hold the left mouse button
2. At search height, position the wedge over your first bondpad
3. release the left mouse button. Do not make any sudden movements with the mouse while in the middle of the bonding process.
4. Adjust the loop height until the wedge is high enough above the sample surface to suit your needs.
5. Check wether the second search height is set correctly for the second bond
6. Move to the second bondpad and press and hold the left mouse button
7. Fine position over the second bondpad.
8. Depress the left mouse button to finish the second bond.

Next to the semi-automatic bonding, it is also possible to control the wedge approach manually which can be convenient in some situations. To enable manual Z bonding set the 'semi-automatic/manual' switch at the right panel to manual (it is located at the rightmost side of the machine). Now you can use the lever at the left hand side of the machine to control the Z position of the wedge. This lever is extremely sensitive so take care when handling it. In manual mode the machine still uses the search height settings to control the bonding process, so make sure these are set correctly (this can only be done properly in semi-auto mode).

1. Slowly lower the wedge using the lever. The lever is very sensitive so take care.
2. When close to the surface, fine position the wedge and then press the lever fully down to initiate the bonding process.
3. After the first bond, the wedge will go up according to the position of the lever. It's maximum from the workpiece surface is defined by the loop height.
4. Next position the wedge roughly over the second bond pad and again slowly lower the wedge by pushing down the lever. With the wedge close to the surface, fine position and make the second and final bond.
5. Release the lever after the second bond has been made, and the wedge will return to reset position.

Always leave the system with the wire in the wedge, write the logbook, clean your workspace and turn of the goose neck lightguide if you used it.

• Open clamp (flip switch on the right)
• Move clamp lifter up (clamp lifter is on the left of the machine, close to the arm)
• Close clamp
• Move clamp lifter down

A nice bond needs to have a nice bow to avoid tension and stress. If a wire is connected straight between contact pads there will be tension on the bond pads.

When making the second bond you want to overshoot over the position you want to bond, then push back the wire to the bonding pad, this way you're releasing tension and create a nice bow in your bond.

Ultrasonic energy is transferred via the transducer to the wedge. It is important that the wedge is installed properly and energy can be transferred without problems. It is important to check this before and during bonding.
On the left panel use the 'TEST' switch, the U/S LED between the 1st and 2nd should light up continuously. \\When loosening or tightening the screw of the wedge always make sure to use the correct height gauge! The height setting of the wedge is extremely sensitive.

10min in the ultrasonic bath in ISO-Propanol

The search height determines the height at which the bond head stops before making the actual first (or second) bond. This allows for fine positioning of the wedge over the bondpad. The search height should be 75-100 μm above the bondpad surface (3 times the wire thickness). A different search height can be specified for the first and second bond, when there is a height difference between the first and second bondpads. When the first and second bond are in the same plane, both search heights should be equal. If you want to bond in manual mode it is still important to set the correct search height, this should be done in semi-auto mode.

After the first bond is made, the wedge is set to the loop height, which is dependent on the bond length needed, whether or not the first and second bond are in the same plane and so on. The value set is an absolute value and does not depend on the search height. This means that when the search height is changed, it is probable that the loop height needs to be adjusted as well.

For wedge bonding, the tail length determines the wire length which is produced after the second bond and is thus also the amount of wire with which the first bond starts.

For ball bonding, it also determines the wire length after the second bond, but this length then is a critical factor in the Electric Flame Off (EFO) process as the amount of wire determines the size of the ball. This means that too little tail produces a too small ball (which can get stuck in the capillary) and too much tail will result in problems when doing the EFO.

The U/S (UltraSonic) power applied determines the amount of energy applied to the bond, by varying the amplitude of the U/S vibrations.

The bonding time determines how long the U/S energy and force are applied to the bond.

The bonding force is applied to the wire, while the U/S energy is being applied. It consists of a static force which is determined by counterweights in the machine itself and an amount applied by the electromagnetic coil. The latter one is determined by the force dial. The value indicated by the dial is merely used to make a recipe which works for specific applications.

Normally when the wedge moves to loop height, the first bond has to withstand extra stress because the wire is pulled from it. This can make the bond weaker or even loosen it completely. To avoid this, a kink can be made just after the first bond, before making the loop. This is done by adjusting the king height and reverse dials.

The first of the two determines to height to which the wedge will rise (and thus the wire length protruding the bond). Adjusting the reverse dial will influence the amount of reverse motion of the table, after the the wedge has risen to kink height. After the table has reversed, the wedge will rise to loop height. This way, when rising to loop height, the kink will be under stress, not the first bond.

The stepback determines the distance the motorized table moves between the first and second bond pads (if they are at a regular distance this is useful). The maximum stepback setting is 6.4 μm. To use the stepback the motor has to be turned on at the right button panel of the machine.

• Heater control to heat up the sample holder to facilitate Au wire bonding, this can be connected to the sample holder.
• Gooseneck bifurcated light guide on top of the bonder

The following wedges and capillaries are available:

• W Wedge - VU45A-W-2025-3/4-CM - used for 25μm Al wire
• Ti Wedge - VU45A-TIB-2025-3/4-CM - used for 25μm Au-wire
• Wedge - 4WNLO-2025-W5C-MOO - used for 25μm Al-/Pt-wire
• Capillary - 40472-0010-324 - used for 25μm Au-/Pt-wire