Gaining Flexibility in SMT Production

30th September 2010
Posted By : ES Admin
By Adrian Schärli, Azular GmbH, for Essemtec AG There is always something that goes not as planned: For example a prototype that must be squeezed in between the running production, a component that has been wrongly specified or a special component for which no feeder is available. It is such a small deviation from the normal that can derange the SMT production planning and lead to delays and increased costs.
With an FLX2011 pick-and-place from Essemtec, the unpredictable loses its hold. It is one of the most flexible machines in the market and, therefore, is the optimal choice for electronics production with high product variety and it features many tools and solutions that enable SMT production to react flexibly to unplanned surprises.

The “In-Between” Rush Orders
This has happened before: Sales promises something to the customer that the production team was not told about. Now it becomes a rush job. In the middle of running PCB A, the PCB B must be fitted. What is a nightmare for many placement machines is no problem for a highly flexible pick-and-place such as the FLX2011.

While the production of product A continues, the operator sets up feeders with the additional components required by product B and installs these feeders on the machine. He uses the offline programming station to convert the CAD layout data of the PCB into a placement program. Then he interrupts the production of product A, inserts a circuit B, loads the assembly program from the network and starts the production. When product B is finished, he continues with product A. During this time, the machine was standing still only while exchanging PCBs.

Changeover without standstill time is possible because of the flexibility and the high feeder count of the FLX. Up to 190 components (L-version: 310) can be installed simultaneously on an FLX2011. The intelligent FLX-feeders can be exchanged during operation and they are recognized by the pick-and-place machine automatically. The magnetic PCB holder can be adapted to different PCB formats without needing any tooling.

Prototypes and Small Quantities
Prototypes often are urgent orders with many specialities. Most often, components are only available in the required quantity or no feeders exist. Despite such difficulties, quality must be perfect from the first PCB assembled because there is neither time nor material available for trials. For such cases, the FLX2011 features helpful functions: The Virtual PCB View, the Pick-Anywhere feature and the Component Verification Unit (CVU).

The Virtual PCB View is a software technology developed by Essemtec and allows the pick-and-place program to be superimposed to the real PCB. Thus, it is possible to verify before placement if placement coordinates are correct, if IC and diodes are aligned correctly, if the correct component size is used, and if all required components are available on the machine. In short: Virtual PCB View allows a quality control before a single component is placed.

The Pick-Anywhere Feature enables components to be picked from any location, even without feeders. Any coordinate within the pick-and-place area can be defined as a pick-up location. This feature allows singular components to be handled without feeders or to pick components from small pieces of tape presented on tape strip feeders. It also allows the implementation of customer-specific feeding systems such as vibration or label feeders.

FLX-CVU (Component Verification Unit) has been developed for PCB manufacturing in the medical and aerospace industries. Small series of highly complex PCBs are common in these industries and the production must be fully documented. With FLX-CVU the value and the polarity of each component can be measured and documented prior to assembly. The measurement system is suitable for resistors, capacitors, inductors and diodes.

Missing Stencils for Printing
The FLX2011 pick-and-place is a dispensing machine as well. The assembly head is expandable with two metering valves and can dispense tow different liquids. This option most often is used for solder paste and adhesive dispensing, for example, if a stencil is not available or for double-sided PCB assembly.

The dispensing program is automatically created from the pick-and-place and the component date ― no additional programming is necessary. The sequence of dispensing and placement is free to choose; therefore, special constructions can be manufactured such as component stacks. Different dispensing valves can be installed, such as micro-jet valves, screw valves and time-pressure valves.

Short-Term Layout Changes
Sometimes a customer calls at the last minute and says, “R434 must be 4.7 kΩ and not 47 kΩ!” What now? CAD data already has been imported, the pick-and-place program is ready and feeders are set up. With the FLX2011, these tasks do not have to be repeated because the Virtual PCB View feature allows short-term modifications directly on the machine.

A simple mouse-click to the component opens a menu where the operator can modify the value, the type, the position and even the orientation of the component. Thanks to the virtual view, the operator can check the modification immediately and also see if the desired component is already installed on the machine. After saving the modification, the production can begin.

Long Delivery Times
Most electronic devices consist of multiple PCB. If those are manufactured in individual series after each other, then final assembly can only start when all PCBs are finished. However, the FLX2011 can shorten this time-to-market and increase profit.

FLX software and the magnetic PCB holder allow different PCBs to be combined to a cluster and assemble it as one PCB. In this way, the different parts of a device are ready faster. Final assembly can start earlier and finish the first device faster. Therefore, it can be delivered and billed much earlier.

The Lack of Inventory and Set-Up Verification
Most logistics systems must capitulate when it comes to the exact number of components. How many have been used, how many have been dropped and how many are still on the reel? In most cases, consumption is only estimated and the real number is rarely known. Therefore, the MIS (Management Information System) software package can be installed that provides several features:
• Update of the component stock based on real consumption data from the pick-and-place
• Identification of each component package (reel, tray, stick)
• Feeder setup control with bar code reader
• Production and consumption planning
• Traceability of the SMD production

MIS knows the content stock of each component package. The MIS planning module delivers information about availability and possible bottlenecks in the planned production. These values also can be provided to external ERP systems.

Because MIS identifies each component package individually and requests feeder setup verification with a bar code reader, production data of each PCB can be documented precisely. If required, MIS delivers all data necessary for tracing a PCB or about the usage of a specific component series.

No Line Disruption Because of Module Failure
The FLX2011 placement system is available in a standalone or inline version. Multiple FLX2011 can be combined to a line for more placement speed and feeder capacity. But even when inline, each module can either produce as a single machine or in combination with others. This offers high flexibility and redundancy.

Depending on current needs, PCBs can be loaded from left or right. For example, module 1 and 2 are loaded from the left and assemble product A together. Simultaneously, module 3 is loaded from the right and assembles prototype B. This freedom also provides security. If one module fails, the remaining two can still produce with 2/3 of the productivity and production does not stand still.

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