|Port-A-Wand handles ICs and wafers.
Handling parts during assembly can entail the use of a variety of different tools. Larger parts can be handled easily by hand without the assistance of any special tooling. Bus as parts become smaller and more fragile, specialized handling tools become more important. For many decades, the handling tool of choice has been the mechanical tweezer. The tool is simple to use and many people have tweezers at home used for such varied applications as removing splinters to plucking eyebrows. A disadvantage of mechanical gripping, however, is that fragile parts may be damaged or dropped during the handling process.
Enter the age of high-technology electronics and the need for manual tools that can handle parts ranging from 300mm to as small as 100µm. The ideal tool for handling parts without imparting contamination, damage or dropping is the vacuum-tweezer. The vacuum-tweezer typically consists of a pen or wand type device with a vacuum source and a pick-up tip. There is a wide variety of vacuum pens available depending on the particular handling application. There are self-contained vacuum pens that are mechanically operated, tools that are battery powered, compressed air-powered tools that have an internal venturi vacuum generator, tools that connect to in-house vacuum sources and systems with vacuum pumps that plug into standard electrical outlets. Each tool has advantages depending on the handling application. These tools are fabricated with materials that render them safe for cleanroom and static dissipative for ESD-sensitive applications.
Manual Vacuum Tweezer
Let's start with the manually operated vacuum tweezers. These tools are ideal for handling parts that are a quarter inch in size up to several inches. There are two basic styles, each requiring rubber vacuum tips for proper operation. First, the pen style PEN-VAC has a button on the side, an internal bulb and an interchangeable rubber vacuum tip attached to the front of the tool. When the button is depressed air is forced out of the tool, the rubber tip is then placed on a flat surface of the part to be handled. Releasing the button draws the air back into the tool. A vacuum is created between the part and the vacuum cup and the part can now be handled. A second depression of the button releases the part. Operation is that simple.
|Tiny parts are handled by continuous vacuum supplied through a hose.
Next in line, there is the Bulb-vac or Handi-vac style. The operation is very similar to the pen style. The bulb has a rubber vacuum tip attached to the front of the tool. When the bulb is squeezed air is forced out of the bulb, the rubber tip is then placed on a flat surface of the part to be handled. The squeeze on the bulb is relaxed to draw the air back in and a vacuum is created between the part and the vacuum cup. The part can now be handled. A second squeeze of the bulb releases the part. The Bulb-vac is especially suitable for placing today's processor chips into sockets on computer boards.
Specialized Pickup Tips
In addition to the different styles of vacuum pens there is a variety of specialized pickup tips for different applications. For example, when handling flat substrates such as wafers, solar cells or flat panels, the tips themselves are flat. These tips require a constant vacuum source to overcome leakage between the substrate being handled and the pick-up tip itself. Substrates handled with this type of device typically range in size from 2 to 12-in. (51 to 305mm).
|Pen Vac self-contained houses battery and mini vacuum pump.
When handling parts smaller than an 1/8-in. (3mm) a small-part tip is recommended. The business end of the small-part tip typically has conical point ending in a flat area with a hole drilled down the center. The holes vary in size from 0.060 to 0.003-in. (1.5 to 0.076mm). The tip with the smallest hole size easily handles 100µm size parts. This style of tip is used with any of the abovementioned systems that provide a constant vacuum source such as the bench top tools that plug into an electrical outlet. In this case the vacuum pen has an air hose connected to the back of the tool and the pick-up tip is on the front of the tool. To handle parts with this system, simply touch the tip to the part and it is gripped for pick and place. To release the part, just tap the control button on the side of the pen. Applications for this style of tip include handling items such as SMD components, small ball lenses, miniature springs, small optical fibers, and other equally tiny and fragile parts.
Battery-powered tools are used where freedom of movement is a consideration. For example, in a cleanroom operation, a battery-powered wafer wand has several advantages. First of all there are no hoses to get in the way. Vacuum hoses in a cleanroom can collect particles that may spread and interfere with deposition of circuitry. Vacuum hoses can be stepped on or tripped over. In addition, a vacuum hose attached to a wafer wand restricts dexterity during the handling operation, which may result in dropped, chipped or scratched wafers. A portable battery-powered wafer wand such as the PORTA-WAND eliminates all of these issues. The handle of this tool contains a miniature vacuum pump, a battery as the power source and a press fit connector on the front of the tool that will accept a variety of different handling tips. The button on the front of the tool is depressed to engage the vacuum. The tip is placed flat against the substrate to be handled and it is firmly gripped for handling. Releasing the button turns the tool off and the substrate is released.
All of the applications for vacuum handling are too numerous to cover in this limited space. Most applications can be solved using off-the-shelf pick-up tips. Some applications require custom tips. Vacuum tweezers provide industry with solutions for manual handling of delicate parts without damage, dropping or contamination.
Contact: Virtual Industries, Inc., 2130 Victor Place, Colorado Springs, CO 80915 719-572-5566 fax: 719-572-5504 E-mail: firstname.lastname@example.org Web: http://www.virtual-ii.com