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This is the second in a series of columns aimed at helping buyers analyze and select SMT equipment for PCB assembly. In this column, I’ll cover manual and semiautomatic pick and place machines, for users interested in going from a couple boards a day to much higher production volumes, while a future column will cover more complex, fully automatic systems.
A pick-and-place machine is the second step in the paste, place, and reflow assembly operation. The place function follows the solderpaste function (stencil printer). The place operation selects and delivers a component over the board and drops it into position. The simplest form of pick-and-place operation is by hand; that is, manually picking a component from a bin and, with the aid of a pair of tweezers and a magnifying glass, positioning it on the board and completing the operation with a hand-held soldering iron.
This method works perfectly fine if you are only doing occasional boards. Other things to consider are the size of the components (big or small), which affect the time required to hand place and solder. Fine pitch components are another issue, where more precision and accuracy are required, and the human factor comes into play. The work then becomes more tedious and time-consuming.
Let’s start by addressing production ranges for various types of machine-assisted manual systems. For purposes of comparison, since all circuit boards vary in size and complexity, we’ll talk about volumes in terms of components per hour, or CPH. This will help you to decide what level of automation you’ll need.
On the very low side of the scale—using a manual hand system—the only expense is the appropriate hand tools for non-machine assisted manual placement. At the high end of the spectrum, these machines are often modular or customized for high-speed unattended operation. Buyers in this market are likely looking more at ROI than initial cost.
Manual and Semi-automatic Systems
A manual pick-and-place system is desirable for small, growing operations that need to increase their hand-held production volumes incrementally while also improving quality, thus reducing rework or rejects; however, the accuracy of placement is still limited by the capability of the operator. Benefits of a machine-assisted manual system include:
• Less operator fatigue
• Fewer placement errors
• Better control
• Improved yield, less rework
A machine-assisted manual system can be equipped with features such as an X-Y indexing table with vacuum pickup head or pen; ergonomic fixturing to help relieve operator fatigue; and additional fixturing for q (rotation) and Z (height) positioning in addition to X and Y.
Editor's Note: This article originally appeared in the February issue of SMT Magazine.