Flying Probe Testing

A quick overview of the SPEA 4060 and its capabilities

 

Summary

The purpose of this document is to give a glimpse about the SPEA 4060 systems for readers who are not familiar with the technology and the fundamental concepts of the Flying Prober.

Even when full documentation about the topics here is available, the focus here is to answer generic questions such as:

These questions are a prelude to answering the fundamental question: What can I do with a Flying Prober?

 

SPEA 4060 Flying Prober Advantages

The Flying Prober concept is relatively new, in comparison with the Bed-of-Nails (BON) systems which have been widely used in production in the past. BON systems were deemed full In-circuit testers (ICT) while the Flying Prober was categorized at some point as an MDA level (Manufacturing Defects Analyzer) solution.

The reality is that the SPEA Flying Prober is much more than an MDA. It is a full ICT system. In essence, the same instrumentation used for the SPEA BON line is used in the FP4060 line. The only difference is how we access the Unit under test (UUT).

Even when this seems like a big negative factor for the FP systems, the advantages easily outweigh those concerns.

 

SPEA 4060 Advantages

With the new smaller technologies and device geometries, the SPEA Flying Probers are a very good investment to meet those challenges because of several reasons:

  1. Flexibility
    1. Because the SPEA 4060 uses clamps to secure the board to be tested in place, There is no need for fixture fabrication, therefore a program can be developed and ready for production in a matter of hours. This is possible because SPEA is a complete solution.
      1. All you need is to provide the files (CAD, schematics, Bill of Materials) and a sample board, and you can have a program pretty quick.
      2. Even if CAD is not available, the 4060 system has tools to help develop a robust test program.
  2. Board coverage
    1. The 4060 can hit targets as small as 3 mil pads, by far smaller than the typical requirements of a Bed of Nails system. This is a fundamental
      improvement since you are able to hit component pads. DFT rules are more flexible.
      1. In almost 100% of the cases, the coverage using a 4060 system will be much higher than the BON systems.
      2. In most cases, the BON systems can test faster but, if you get only 10-20% coverage, then it is not practical!
      3. On the other hand, the SPEA 4060 systems may not be as fast, but if you get >80%, then your process is improved dramatically.
    2. b. The 4060 system also uses optical cameras to inspect any components for which electrical testing is not possible. For example, connectors, parallel and polarized capacitors, etc.
  3. Operation expenses
    1. This is very important especially for high mix / low volume situations. If you consider that a fixture (for BON systems) may cost $2-10k (or more), this can be a big burden. But the 4060 system does not require that! So the savings can be substantial.
    2. In the case of fixture fabrication for the BON systems, delivery can take 2-4 weeks. For the 4060, you don't need to wait!
    3. Engineering Changes can be accommodated immediately with simple programming changes and no fixture rework is required.
    4. Also, by having high test coverage early in the process, you increase the first-pass yield during functional testing. Troubleshooting late in the game is very costly. The SPEA 4060 systems prevent that.

 

SPEA 4060 A closer look at the technology

For BON systems, electronics and software are the central elements to be considered. With them, reliability, repeatability, and productivity become topics of discussion. Yes, a fixture must be fabricated, but it is considered an addition, rather than a part of the system.

A third element plays an important role in the Flying Prober world: mechanics. Its importance is enhanced because of:

  1. The FP system must be fast. Otherwise, the cycle time gap between this and the BON concept makes the FP not very attractive.
  2. Accuracy and repeatability. Remember, we are using targets much smaller than the conventional BON approach.

Among the different technologies available in the market, the SPEA systems use the Linear Motor approach. In the market you can find other options:

 

SPEA 4060 The only system with Linear Motors

The Linear Motor concept used in the SPEA systems is based on:

It is important to note that this technology is being used in the high end pick-n-place systems, which require similar speeds and accuracy to lead the market.

 

SPEA 4060 Measurement Accuracy

SPEA is an engineering company. For over 35 years, the systematic approach at research and innovation has paid dividends. This allows our products to be always at the vanguard in the industry, finding ways to continue improving its performance and reputation along the way.

With the new 4060 series, a major improvement is introduced. The 4060 is the first system in the market to implement the measurement processing at the head level. Traditionally, the head only contained the signal capturing assembly; this signal (analog in nature) would the travel several feet of cabling in order to reach the instrumentation cage, where it would be processed and analyzed. This setup would compromise to some extent the signal integrity.

The new 4060 systems place the signal processing module at the heads, reducing the distance to be traveled to approximately 4 inches. Once it reaches the processing module, the measurement is processed and converted into a digital signature (ensuring signal integrity). This digital signature then travels to the instrumentation cage.

 

The benefits and implications are enormous.

There is no other system in the market with this technology. It is a true differentiator.

 

SPEA 4060 Full ICT test system

It is important to reiterate that the 4060 system is a full In Circuit Tester – not an MDA (Manufacturing Defects Analyzer). What this means is that the 4060 will test every component for the correct parametric (datasheet) properties, not just for presence. For example:

And that is just the beginning. A superior set of instruments allows the 4060 to be a full engineering tool such as a waveform generator and counter timer. Flash programming, Boundary Scan, and external instrumentation can be implemented if desired.

There are many different types of testing techniques that the Leonardo software allows the programmer to perform on the UUT such as:

 

ICT TEST – Testing at the component level.
Nodal Impedance Test (NZT) – Testing at the net level. Every net is verified against a learnt impedance value (res/cap/diode) in reference to GND. Idea for large boards or repair centers.

OPEN PIN SCAN – Ideal for finding lifted pins or orientation/placement issues on Digital Devices including BGA's and QFP's.

OPTICAL TEST – Every component for which electrical testing is not possible is checked for presence/orientation/character verification. For example, polarized and parallel capacitors, connectors, etc. A camera is mounted on the flying heads perform a thorough check of these devices.

POWER ON AND HIGH POWER TEST – The 4060 systems have multiple Programmable Power supplies. Any V/I combination required is possible. Once power up is achieved, a full array of testing can be applied to the UUT.

OBP/BSCAN – Great solution for flashing devices or implementing any of the Boundary Scan solutions (JTAG/Corelis/Goepel/Asset/etc.).

 

SPEA 4060 Mechanical Arquitecture

Our test techniques are possible because the FP4060 has heads on top (4) and bottom (2). As an option, customers can select top side only.

 

In addition, up to 248 signals are available via connector. This is essential for any type of fixed signals, power up, digital signals, or external instrumentation. Flash Programming as well as Boundary Scan settings can easily be achieved via this method.

 

Introducing Leonardo Development Software

On top of all the great things about the SPEA systems, it is very important to discuss another major differentiator: Leonardo. Developed 100% in-house, Leonardo is the operating software for development and testing.

Leonardo is written in a way that it gives complete control to the programmer using a graphical user interface of what type of tests they would like to generate for any UUT.

Leonardo is not just a program. In essence, Leonardo is a Suite composed of several programs. All of them look rather similar, except that each will focus on a different concept.

 

There are also several programming modes:

 

SPEA 4060 Debug Modes
In the past, development and debug required a relatively substantial amount of time. Leonardo changed that in a radical way. Now, advanced algorithms assist the developer in making the entire process more automated. A process that could take 1 day or more is now reduced to 4 hours or less!

The following are brief descriptions of available options for the program developer.

Auto Debug
It automatically executes the operations required to correct the tests that fail because of specific board circuit configurations. The software performs a wide array of engineering debug steps to troubleshoot any failing tests. What is important is that the software makes no assumptions. If a 10kOhm resistor reads 7kOhms, there is a reason why so, the software will help determine the root cause. Learning a value may be dangerous so, this tool helps producing a very robust test plan.

Auto Tuning
To accompany Auto Debug, Auto Tuning was introduced to tackle another important aspect in the process: Maturing a test plan.
Auto Tuning makes an analysis (Cp and Cpk) of each test to make sure the stability and repeatability is acceptable. This is critical to account for process variability. False failures are accounted for, early in the life of the program! Any unstable test is addressed to avoid process instability.

Auto Learn
And if you want to take a signature of a GOLD board, it is very easy. This can be useful when time-to-test is very tight!

 

SPEA 4060 From A to Z

The SPEA platform is very attractive because in covers every aspect of the development/testing process. A good example is CAD importers.

While other Flying Prober solutions in the market will ask for third party assistance to translate/prepare the development input files, SPEA takes care of the entire process internally.

- The Leonardo CAD suite supports over 40 different software packages. Dependency on solutions such as Fabmaster (which adds cost in licensing fees) is no longer required.

 

SPEA 4060 Summary

SPEA has been 35 years in the market, always in the electronics testing sector. Along the way, it has set the standard for the Flying Prober systems. About 50% of the SPEA workforce is composed of engineers. And about 33% of the revenue it's poured back into R&D. This translates into the most advanced, robust, and user friendly systems in the world.