Optimal for Suction Transfer Processes in Crystal Oscillator Manufacturing! The Functionality of the Pick and Place Robot

What is a Crystal Oscillator?

When you hear “crystal oscillator,” what comes to mind? Crystal oscillators are essential timing devices used in all sorts of electronic devices, from smartphones to computers. Think of them as being similar to a metronome, which you may remember from music class. A metronome can help us produce good music because it marks a constant tempo, neither speeding up nor slowing down. As you might have experienced, it's hard to keep to a set tempo when many people are playing music together.
Another place where we find crystal oscillators is in our clocks. In a quartz clock, the quartz serves as the crystal. Crystals produce a piezoelectric effect such that they can emit a signal at a set frequency when combined with a circuit and subjected to an electrical current. As a metronome is a reference for the tempo for music, the set frequency signal of a crystal oscillator serves as a reference for time.
The latest computer CPUs operate at clock speeds (the number of cycles a CPU executes in a second) measured in GHz. It might be hard to picture, but 1 GHz is like a metronome striking 1,000,000,000 beats per second. Crystal oscillators are indispensable for accurately producing those kind of frequencies. If there’s a CPU chip mounted onto a board, it’s safe to assume there is also a crystal oscillator mounted onto it as well.
* While this explanation of timing devices is limited to crystal oscillators as a representative example, other kinds of timing devices exist as well.

Structure and Manufacture of Crystal Oscillators

The structure of a crystal oscillator typically looks something like the image below.
As mentioned above, crystals produce a piezoelectric effect, meaning that they change shape when subject to an electric current, so the space around them needs to be empty. A crystal blank is set onto two or four points where electrically conductive adhesive has been applied to a base so that the center of the blank is raised, and a cover is placed over it. This is the general structure of a crystal oscillator.

Setting Components onto Adhesive

In the third step of the process above, when the workpiece is mounted precisely to its installation position, the Z axis needs to either move down to a set height or press down with a set amount of force.
Traveling down to a set height involves positioning control that utilizes position information from an encoder to stop at precisely the desired location. This is a normal motion that even conventional devices can produce.

But what kind of problems can arise when this process is actually performed?
Ideally, the workpiece is placed in exactly the right location at the right angle, height, and orientation. In reality, though, variations in workpiece thickness and base height can create either too much or too little clearance. Additionally, because the adhesive is a fluid, it's difficult to strictly control how it behaves, which can create discrepancies in the amount of adhesive and how it is applied to a surface. When these issues occur, they can cause the kind of defects shown below.

Using the PPR System

Optimizing the Bonding Process for Component Assembly

In this article, we focused on improvements for the bonding process utilizing the Pick and Place Robot PPR using crystal oscillators as an example application. To see more concretely what the PPR is capable of, see the video below, where it is installed onto a machine for a test. A waveform of the picking operation is available as well.