Vacuum Technology for Printed Circuit Board Assembly

Following the manufacture of blank printed-circuit boards (PCBs), the boards are assembled with various electrical parts and components. Resistors, IC chips, capacitors and all manner of interfaces are used in the PCB assembly, depending on the individual requirements and layout. The high number of different components, along with their diverse geometries and properties, places very high demands on the necessary vacuum technology. High cycle times and positioning accuracy are additional requirements that can be addressed with vacuum technology from Schmalz.

As in the case of PCB manufacture, Schmalz offers solutions for a number of different process steps. Schmalz distinguishes between the handling (automation) and the use of vacuum technology during a process step (process vacuum). The following table provides an overview of some of the most important process steps:

Process stepDescriptionVacuum handling (automation)Process vacuum
1PCB handling
2Automated optical inspection (AOI)
3Application of soldering paste
4Assembly
5Reflow soldering
6AOI
7Rotation
8Application of soldering paste
9Assembly
10Reflow soldering
11AOI
12Function test
13Packaging

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Schmalz Inc.
5850 Oak Forest Drive
Raleigh NC 27616
United States of America

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F: +1 919 713-0883
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A wide range of technologies can be employed in the assembly of PCBs. By way of example, components can be connected to the PCB using through-hole technology (THT) or surface-mount technology (SMT). Depending on the application, both technologies can also be combined on a single PCB to reap the benefits of both mounting types.

The following provides more details on the individual process steps involved in the assembly of printed-circuit boards. Information on the use of vacuum technology in PCB manufacture can be found here

Diverse Applications of Vacuum Technology During PCB Assembly

Incoming Material Inspection and Initial Steps

To begin with, the blank PCBs are taken to the in-line assembly lines (1). Before any subsequent processing takes place, an initial inspection is performed (2). Following the incoming inspection, the soldering paste is applied using a squeegee blade and a mask (3). After additional inspection steps, the components are positioned on the PCB (4).

During these process steps, Schmalz vacuum technology is used, among other things, for handling the individual electronic components. More information on the requirements of vacuum technology can be found here.

Soldering the Components and Preparing the Reverse Side

During the reflow soldering process (5), the PCB is heated such that the previously applied soldering paste melts. Following a further inspection (6), the part-assembled PCB is rotated (7) so that the second side can be assembled. As with the first side, the soldering paste is applied (8), visually examined and inspected for errors.

Vacuum technology from Schmalz can also be used to rotate the partially assembled PCB. Details on how Schmalz products satisfy the requirements of the various process steps can be found here.

Assembling and Inspecting the Second Side

The reverse side of the PCB (9) is assembled in the same way as the previously assembled side. Different pick-and-place machines are required depending on the parts and components employed. The reflow procedure is once again used to connect the components to the PCB (10). The following inspection (11) and subsequent function test (12) are performed on the basis of custom test protocols for the specific board. The finished and inspected PCB is then prepared for transport (13).

As with the first side, Schmalz vacuum technology can also be used to process the reverse side of the PCB. Further information on the different applications and suitable products is provided below.

Vacuum Technology Requirements

Due to the diversity and countless geometries of an assembled printed-circuit board, a PCB handling solution is required that compensates for the height differences of the components while also preventing damage due to mechanical stress. Thanks to its extremely high flow rate, the Schmalz flow gripper SCG is ideal for handling circuit boards and uneven components. The sealing lip adapts to the different geometries. The partially projecting solder tags used in the THT process create height differences that can be compensated by the floating suction cup SBS (based on the Bernoulli principle), thus enabling effective handling.

Vacuum technology is used not only in the assembly process itself, but also for the component supply station ("feeder") of the pick-and-place machines. Whether for the blister tape reels ("Tape&Reel") or the tray supply: Schmalz suction cups can be used to great effect in both areas. Schmalz also offers suitable products for larger components and for provision in plastic tubes.

Products for Use in Printed-Circuit Board Assembly

Flow Grippers SCG

  • Suction rate: 270 l/min to 650 l/min
  • Diameter suction plate: 20 mm to 60 mm

Floating Suction Cups SBS

  • Diameter: 20 to 120 mm
  • Holding force: 2.0 to 104.0 N
  • Rubber buffer on the bottom side of the suction cup

Bellows Suction Cups FSG (2.5 Folds)

  • Diameter: 3 to 88 mm
  • Material: HT1, NBR, NBR-AS, NK, SI, SI-AS, SI-HD
  • Connection nipple plugged into elastomer part

Compact Ejectors SCPS / SCPSi

  • Suction capacity up to 67 l/min
  • Max. vacuum: 85 %
  • Body made of plastic