Zero Defects

Published on 6-Jan-2009

Guaranteed best-in-class board quality for automotive and other quality-sensitive industries

Veldhoven, April 25th

Every industry aims for zero defects. But for industries like automotive, military and medical, zero defects are a necessity. The extremely high cost of field recalls and the growing need to meet tough legal and safety regulations make product quality and production reliability major considerations.   

After buying manufacturing equipment, it is important to ramp up immediately with zero defects – but also maintain that performance over the equipment lifetime. This can only be achieved by monitoring product, process and design. One approach is “6-sigma”, which drives towards ‘Total Customer Satisfaction’.

Assembléon’s aim towards zero defects reaches through the whole organization, and is itself demonstrated by our new A-Series equipment. Recent independent studies have confirmed that Assembléon leads in board quality levels. Whereas average board level quality was above 50 defects per million placements, Assembléon has repeatedly shown defects per million below 10.

More information on the defects per million equipment comparison can be found at facts.

Product quality, which reflects your whole company image, cannot be built in by continuously reworking your products at the end of the production line. High rework levels seriously influence product end-quality, while pushing up the overall cost of quality.

Producing fewer defects can save millions per year. That is in particular true for high volume production, but also for small batches where boards have many components. The more components on a board, the higher the chance of a defect on that board, and thus the higher the chance on rework or recall because of that defect. So, as the number of components increase, the yield rate of PCBs get worse. It is very important to maintain the placement error rate at very low level.

More information on saving costs reducing defect levels can be found at facts.

Pick & Place machine speeds are increasing. This can be done by adding more heads, by adding more nozzle positions on a rotary head, or by increasing the robot’s speed, acceleration or rotations. However, increasing speeds can place enormous forces on components that are attached to the nozzle. This can go unseen, since alignment comes well before placement, and will lead to uncertainties in placement quality.

Assembléon machines are renowned for their high outputs, but this does not come not speeding up the individual robots but originates through its  zero defect design: true parallel placement.

We don’t make a single robot with one head and multiple nozzles that do all the work, but rather share the load across amongst  (up to) 20 individual robots. All have one head and one nozzle, moving parallel to each other at a relatively slow and controlled pace. There is a huge difference between having one robot trying to place 100,000 components per hour or having  20 robots placing just 5,000 components per hour. Lower speeds means fewer faults, so the 20 robots are much more likely to reach zero defects – while having longer lifetimes.

Zero defects on AX-301 and AX-501 – by design

When designing a robot, picked components must always be placed correctly on the board at the right location, and with the right force. With the AX-301 and AX-501, this placement process is continuously monitored and users are warned when the process window boundaries are being approached. That is the only way to guarantee placement quality throughout a machine’s lifetime.

Assembléon’s complete Pick & Place cycle is fully software controlled and can automatically adapt itself to the current situation. Irregularities at the pick position are corrected to make sure you are always spot-on at the center of the component  Once the component is picked, its presence is continuously monitored all the way until it is placed on the board. Just as with the feeders, any irregularities in the PCB are detected, calculated and implemented for the next placement. That helps to avoid accidental early impacts with warped boards, and also avoids possible side-effects of placement on very thin boards where to hard pressure into the board may cause a trampoline effect, dislocating the component(s).

Checking that a component has been placed is simply not enough. You must be sure that the component is placed with the correct rotation and centered as much as possible on the pads. These requirements are very important for successful soldering. The more accurate the components are placed on the pads, the more reliable the end result.

Since Assembléon uses single-head/single-nozzle robots, the component is measured at all times – from above the pick location to right above the place location. With the component orientated correctly the only direction of the nozzle is downwards, so the component is not exposed to any rotational forces. A guarantee for continuous successful placement quality.

 
Placement quality                             Non quality

More information on the A-Series specifications can be found at A-Series specifications

With the ongoing miniaturization of components – and the increased popularity of placing bare die products (flip chips) – it is very important not to damage these components. With the smaller components like 01005 (0.4 mm x 0.2 mm), component manufacturers specify that the placement force should stay below 2N. The A-Series equipment guarantees placement forces as low as 1.5 N (for AX-301 and AX-501) or 0.9 N (AX-201) without having to compromise any other machine parameters like speed or board warpage correction.

The single-digit placement defects per million of Assembléon’s A-Series Pick & Place machines set a new benchmark. With 6-sigma design criteria, that offers board manufacturers best-in-class first-pass yield over the whole machine’s lifetime.

More information on the parallel placement advantages can be found at facts.

In the next issue: Zero defect design of the advanced AX-201.