Requirements of High Current Test Probes

High current test probes are usually used to test high current applications. The maximum continuous current rating of a spring probe is determined by its design, size and construction. Typically used probes have a current rating of 2 to 8 amps maximum continuously current at working travel. But the high current probes have a range of 10 to 150 amps and beyond. High current applications require a much more solid and rugged probe to withstand high temperatures.

Features of high current test probes – 

• Low Resistance Plungers

• High Current optimized base material and plating

• High temperature spring design

• Specialized high current tip geometry

With the increasing amount of current any resistance within the probe will generate heat. High current probes are becoming increasingly important inefficient power generation and distribution. Recent developments suggest that devices operating at higher voltages are able to handle higher currents. The industry has been categorizing the levels of the devices – high current and high voltage modes.

While calibrating a clamp meter the current coil that has been designed has to have a high current carrying capability to make it more current capacitive. It should be able to dissipate heat as much as possible. Coils typically have maximum operating time at higher current levels. Not all calibrators can do the job of calibrating the clamp the meter as it requires a high current carrying coil to perform the task. 

These probes have been used in several industries and applications with high currents, such as testing, function tests, signal transmission, power supply in production, as well as assembled contact elements. Another field of application is precise measurement, which requires test probes with very low resistance, so-called low resistance test probes.

High current probes have given way to ultra-high current probe which are made to handle current test up to 300A. These probes are the first ever to easily alternate between high current and high voltage setups. 

Some advantages of high current test probes: 

Reduced measurement time – Testing both high voltage and high current conditions with a single touchdown.

Accurate Characterization – Wide range of pad sizes and test currents, with minimum pad damage and contact resistance

Safe, Reliable and Repeatable high-current/voltage measurements – Suitably recommended for high temperature range

Reduced pad damage from probing due to single touchdown and measure both high current and high voltage.

Spring Contact Test Probes

Spring Contact Test Probes are equipment which is used as test connector-cable systems. These equipment create an electrical connection between the object to be tested and the testing system. Primarily deployed for electrical testing of connectors, printed circuit boards, cables, and various other electrical components and assemblies these instruments prove instrumental in the connection between two electrical circuits or boards.

These contact probes are made up of a tubular barrel, a spring and a plunger. There are many varieties of tip styles and different spring pressures that ensure the best contact with the test surface. Spring contact probes are suitable for all contacting in two terminal measurements which does not require tolerance compensation. 

Benefits of Spring Contact Test Probes

•    Small initial outlay

•    Contact can be changed quickly

•    Ideally suited for signal lines and currents

•    Contact Spacing from 0.4 mm

•    Low maintenance costs

•    Available with floating mounting on request

•    Extensive standard product range.

These probes are available for various applications:

Used as a threaded probe to provide a secure fit. Used for the test of wire harnessing.

Used for high current applications and designed for very small probe resistance.

These probes can be used as special probes with integrated switch elements, mainly used for presence.

Radio frequency probes – Special spring contact probes are used to transmit high-frequency signals. These probes have an inner conductor for the transmission of the signal and an outer conductor for shielding.

Flying Probe Test Systems

Flying probe tester is a form of automated test equipment that has been in use around 1986 when the first testers were introduced. Flying probe testers provide many advantages over other forms of automated test equipment for particular application and purpose. In the initial days flying probe testers were introduced to cover the prototype and very small quantity production areas. Now the use of this type of automated test equipment has expanded, and although not used as the main test in high volume production, they are nevertheless used in many areas.

Flying Probe

The concept of flying probe test system is that rather than having a comprehensive fixture for a given PCB assembly that can access all the required nodes via a “bed of nails”, the system uses a generic board holder, and one or more probed moves across the board accessing individual nodes under software control. The flying probe tester is therefore able to cut down on the number of test fixtures that are required and it’s easier to introduce changes, especially to features such as component or pad positions because it is just a matter of changing the software controls.

Advantages of Flying Probe Tester

No special EOL Fixture required: The probes move accordingly under software control to make contact with the required nodes, the “bed of nails” and the fixture requirement is not needed. Rather a simple generic mechanism to hold the board in place is needed.

Changes can be made easily: Due to the presence of software control the pads also move accordingly and do not require manual handling. It is not required to make any mechanical changes to the fixture.

Test Development time is not needed: Time is easily saved because the first and foremost thing that has been put off is the mechanical requirement that is not carried out. Due to the availability of software control it is done easily.     

Disadvantages of a flying probe:

Speed is slow – The flying probe is relatively slow as compared to as compared to other forms of automated test equipment such as an ICT because the probes have to physically move to each position in turn.

Complicated tests are not easy to perform through a flying probe. It is necessary to check the performance of the individual flying probe tester to ensure it can meet the requirements. 

Sockets for the Semiconductor Industry

Hand crafted test Sockets are intended to be composed and manufactured by client prerequisites, for the most part utilized as a part of the semiconductor business. It can be utilized for Bench-top Testing or for machine automation test as well. Basically, the ability of these items ranges from 1.27 mm pitch size down to as small as 0.2 mm pitch. The most commonly utilized materials for assembling Test Sockets are Torlon, Ultem, Vespel, Peek, and Ceramic, etc. However, it can be possible to produce with all materials on client demand. It can be fabricated for gadgets ranging from QFN, BGA, PGA, and TSOP and so forth. 

Sockets

The test pin-tally per test sockets can extend from as low as 4 pin QFN gadgets up to as high as 3.500 pin BGA gadgets. The strength and the nature of these items meet the most astounding client prerequisites and requests. 

To figure out the test sockets such information is needed, as given below-

• POD (Package Outline Drawing) of the Device IC

• (L x W x H) limitation for test Plugs size is necessary for a Bench-Top Test.

• Brand of the Machine Handler, Preferred Test Height is required for a machine test.

• It can be even possible to make this product according to the customer requirement but for that, a probe pin drawing or a sample probe pin is required. 

Burn-in Sockets:

Generally, as you know that burn-in Sockets are functioned as use and discard product, so diverse necessities are required. Many of these sockets are molded and in these cases standard models are accessible.

Equip-Test

Typical applications are such as EMMC, BGA, QFN, QFP, CSP, LCC, FPC, CPU, GPU, DVB, etc. 

QA Technology Spring Loaded Test Probes and Sockets-

• Spring Loaded Test Probes provide a wide assortment of point styles to suit practically any test necessity.

• Plungers are made of beryllium copper or steel, and then warmly treated, plated gold over nickel.

• Patented test plan includes a calculated plunger tail for enhanced biasing that guarantees reliable contact with the test tube.

• Springs are built of high-quality music wire or stainless steel for long life 

• "QA" remains for quality assurance in each test and attachment.

• Probe tubes are profound drawn from an assortment of compounds and highlight solidified valuable metal cladding for high performance.