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FAQs About Our MicroHELIX Pogo Pin Probes and Test Fixtures

Here are our answers to some frequently asked questions about AlphaTest Corporation's MicroHELIX pogo pin probes and test fixtures that offer unparalleled performance, accuracy, and reliability. Our durable MicroHELIX probes have proven to last hundreds of thousands of test cycles, providing long-lasting, accurate, and reliable testing capabilities. Read on to learn more about made-in-the-USA products by AlphaTest Corporation.

1. Are these pogo pin probes suitable for burn-in applications and/or for use as rf test probes?
• Absolutely. The MicroHELIX® Test Probe is designed to withstand burn-in test temperatures with no need for lubricants. The gold-to-gold contact within the probe ensures resistance against tarnishing at high temperatures. Plus, the metals used in all models have an operating range that far exceeds burn-in test temperatures.

RF Applications require a temporary test connection which is electrically invisible or at least electrically nonintrusive. Ideally the contact would have compliance and zero length. Since that is itself a contradiction, the next best combination is just enough compliance and little length since length introduces some series inductance, capacitance, resistance and some signal delay. That makes our small diameter and short length test probes the perfect choice for two reasons. First, package configurations often require 0,5 mm (or closer) spacing of electrical test contacts. Second, at the rf frequencies involved in testing wireless technology (such as Bluetooth^® technology) and other telecommunication, radar, and sensor devices the signals would be attenuated and/or distorted by conventional test probes. See TN0026 for additional information about the characterization of rf test probes.

2. How long do these spring contact test probes last?
• You can rely on these miniature test probes for over a million cycles of operation at half their maximum compliance. Extensive laboratory tests have shown that the S500*3800 Series spring contact probes maintain their probe force and series resistance even after five million operations.
• The S300 and S200 Series microprobes have less compliance than larger diameter pogo-style probes, making them ideal for applications requiring less compliance. These smaller probes also provide over a million cycles of operation without coil failures or increased resistance as long as periodic cleaning is performed to remove any non-conducting material or contaminants transferred to the probe tip.
3. How much current can these semiconductor test probes handle?
• Based on temperature rise, the current ratings vary slightly within each diameter group. Here are some rule-of-thumb ratings to guide you:
• S500 Series™ (0.020" diameter probes) can handle 2 Amps of continuous service.
• S400 Series™ (0.016" diameter probes) can handle 2 Amps of continuous service.
• S300 Series™ (0.012" diameter probes) can handle 1.5 Amps of continuous service.
• S200 Series™ (0.008" diameter probes) can handle 0.5 Amps of continuous service.
• For pulsed current, which is often required for semiconductor device testing, the limits are generally determined by heat rise rather than probe burn-out.
4. Where are our high-quality precision test probes and fixtures/sockets made?
• Our micro-sized test probes and fixtures/sockets are proudly made in the USA. AlphaTest Corporation, established in 1991 in Mesa, AZ, has been providing accurate and reliable solutions to challenging testing problems. Recognizing the industry's demand for smaller substrates and the continued need to probe them, we developed the innovative MicroHELIX test probes, beginning with our S500 and S400 Series.
• With our unique construction, we eliminated the limitations of wound springs and created pogo pins that can be placed in closer centers than ever before. Our miniature probes do not require receptacles, which allowed us to develop even smaller semiconductor probes for testing microelectronics, our S300 and S200 series.
• We offer various configuration options, including spring contact probes with fine-pitch capabilities, wide bandwidth, controlled impedance, low inductance, Kelvin connections, and static dissipation. Since their introduction, our MicroHELIX pogo pin probes and test fixtures have gained a solid reputation for their quality and durability. Relocating to Shelton, WA, in 2007, we have been operating in our current facility since 2012.
• In addition to the lathes used in manufacturing our semiconductor probes, we have two CNC vertical milling machines and a full range of testing, inspection, and quality assurance tools. Trust our fine pitch fixtures and spring contact probes to provide long-lasting, accurate, and reliable testing.
5. What fine pitch or center-to-center spacing can be achieved with our durable probes and precision fixtures?
• Our long-lasting probes and precision fixtures can achieve fine pitch or close center spacing as small as a quarter of a millimeter or .0254 mm, in high-density arrays utilizing the S200 Series MicroHELIX Test Probes. Please refer to the chart below for the closest recommended centers for our other sizes.
• Achieving precise drilling accuracy is crucial when working with close centers. It can be improved by using homogenous engineered plastics such as Techtron®, ULTEM®, unfilled TORLON®, DELRIN®, PEEK®, Vespel®, Pomalux®, and more. For detailed manufacturer specifications and characteristics of these materials, please consult AlphaTest Tech Note TN0019.
• By using these high-quality materials, the machine operator can drill probe guide holes with straightness and achieve the fine pitch spacing indicated in the following table. It is generally advisable to avoid materials with embedded fibers, as they can reduce drilling directional accuracy.



Probe Series:	S200		S300		S400		S500
	microns	(inches)	microns	(inches)	microns	(inches)	microns	(inches)
Probe Diameters:	200	(0.008)	300	(0.012)	400	(0.016)	500	(0.020)
Minimum Centers:	254	(0.010)	363	(0.0143)	477	(0.0188)	592	(0.023)
Minimum wall thickness:	13	(0.0005)	20	(0.0008)	20	(0.0008)	20	(0.0008)



6. What diameters and lengths are available for the microprobes?
• Our microprobes come in a variety of diameters and lengths. We have catalog probes that are readily available off the shelf or in short delivery times. If you need a custom or special probe, we can accommodate that as well, although it may take longer and incur additional charges. Custom versions can be tailored to meet a wide range of specifications.
• If the catalog options do not match your length, force, diameter, compliance, and tip shape requirements, we can create a unique probe specifically for your product plan.
• The standard catalog for AlphaTest MicroHELIX® Test Probe includes four diameters:



Group ID	Diameter
S500 Series	500 micron	(0.020")
S400 Series	400 micron	(0.016")
S300 Series	300 micron	(0.012")
S200 Series	200 micron	(0.008")



• S500 Series Probes in Eight Standard Lengths:



S500 Series	Body: μm (inches)		Plunger: μm (")		i/o Pin: μm(")		Overall: mm (")
S500*6350-P1 Group	6350	(0.250)	1900	(0.075)			8,25	(0.325)
S500*6350-P2 Group	6350	(0.250)	1900	(0.075)	1900	(0.075)	10,15	(0.400)
S500*5500-P2 Group	5500	(0.217)	1300	(0.051)	1300	(0.051)	8,10	(0.319)
S500*4500-P2 Group	4500	(0.177)	1300	(0.051)	1300	(0.051)	7,10	(0.280)
S500*3800-P1 Group	3800	(0.150)	1300	(0.051)			5,10	(0.201)
S500*3800-P2 Group	3800	(0.150)	1300	(0.051)	1300	(0.051)	6,40	(0.252)
S500*3000-P1 Group	3000	(0.150)	800	(0.031)			3,80	(0.181)
S500*2440-P1 Group	2440	(0.096)	610	(0.024)			3,05	(0.120)



• S400 Series in Six Standard Lengths:



S400 Series	Body: μm (inches)		Plunger: μm (")		i/o Pin: μm(")		Overall: mm (")
S400*6350-P1 Group	6350	(0.250)	1900	(0.075)			8,25	(0.325)
S400*6350-P2 Group	6350	(0.250)	1900	(0.075)	1900	(0.075)	10,15	(0.400)
S400*4500-P2 Group	4500	(0.177)	1300	(0.051)	1300	(0.051)	7,10	(0.280)
S400*3800-P1 Group	3800	(0.150)	1300	(0.051)			5,10	(0.201)
S400*3800-P2 Group	3800	(0.150)	1300	(0.051)	1300	(0.051)	6,40	(0.252)
S400*2440-P1 Group	2440	(0.096)	610	(0.024)			3,05	(0.120)



• S300 Series in Three Standard Lengths:



S300 Series	Body: μm (inches)		Plunger: μm (")		i/o Pin: μm(")		Overall: mm (")
S300*3800-P1 Group	3800	(0.150)	1300	(0.051)			5,10	(0.201)
S300*2300-P1 Group	2300	(0.091)	1000	(0.039)			3,30	(0.130)
S300*2050-P1 Group	2050	(0.081)	450	(0.018)			2,66	(0.105)



• S200 Series in Three Standard Lengths:



S200 Series	Body: µm (inches)		Plunger: µm (")		i/o Pin: µm (")		Overall: mm (")
S200*3800-P1 Group	3800	(0.150)	1300	(0.051)			5,10	(0.201)
S200*2300-P1 Group	2300	(0.091)	1000	(0.039)			3,30	(0.130)
S200*2300-P2 Group	2300	(0.091)	1000	(0.039)	1000	(0.039)	4,30	(0.169)



7. What is the force of the pogo pins?
• At AlphaTest Corporation, we offer standard catalog probes with various probe force options. If you require different force values, we can provide them upon request, including lower force with reduced travel. Here are the force options for our different series of probes:
• S500 Series Probes: 0.5mm (0.020 inches) diameter; 30 grams (1.1 oz) and 90 grams (3.5 oz).
• S400 Series Probes: 0.4mm (0.016 inches) diameter; 30 grams (1.1 oz) and 80 grams (3.5 oz).
• S300 Series Probes: 0.3mm (0.012 inches) diameter; 30 grams (1.1 oz) and 60 grams (2.1 oz).
• S200 Series Probes: 0.2mm (0.008 inches) diameter; 30 grams (1.1 oz) and 40 grams (2.1 oz).
• MicroHELIX Semiconductor Test Probe Force:
• For our MicroHELIX semiconductor test probe, we rate the force at the typical test compression, which is usually half of the maximum compliance. For example, a descriptive model name like "S500*3800/900/30@450/S1300s/S0a" indicates a force of 30 grams at 450 microns of compression.
• Linear Relationship Between Probe Force and Travel:
• To visualize the relationship between probe force and probe travel (stroke, compression, compliance), we have provided a force chart for the S500*3800/900/30@450// Probe Group. The probe force is shown on the vertical axis, while travel is represented on the horizontal axis.






8. What kind of plating is used on the semiconductor probes?
• We use a gold strike/Type III/Type II Gold plate with a thickness of 60-80 micro inches on all tube/coil assemblies, plungers, and pins in our standard catalog probes. Nickel (to repel solder buildup) and PdCo (Palladium Cobalt to repel solder buildup) may be applied for special orders.
9. What equipment do I need to drill guide holes for the small microprobes?
• For drilling guide holes, you'll need an xy position accuracy of 2.5 microns (0.0001"), the ability to peck the drill, and a spindle speed of at least 7,000 rpm (preferably programmable from under 7,000 to 50,000 and ideally programmable from below 7,000 to 120,000 rpm).
• The CNC drill instructions may vary slightly based on the available spindle speed. To prevent heat buildup, drill with a pecking action. This will clear debris from the hole and minimize loading in the drill flutes. Maintain a high cutting speed. For comparison, use a 10,000 rpm spindle speed when determining the cutting speed for these drills.



Example: Drill cutting-speed vs Drill Size using 10,000 rpm cutting-speed in units/time = PI*(Dia in units)*(rpm)/(60 sec/min)
Drill Size			Cutting Speed		Application
	microns	inches	mm/sec	inches/sec	guide-hole for:
#74	572	(0.0225)	300	(11.8)	S500 probe body
1/64"	397	(0.0156)	208	(8.2)	S500 plunger | i/o pin
#77	457	(0.018)	239	(9.4)	S400 probe body
#80	343	(0.0135)	180	(7.1)	S400 plunger | i/o pin
					S300 probe body
#88	240	(0.0955)	126	(5.0)	S300 plunger | i/o pin
					S200 probe body
#96	160	(0.0063)	84	(3.3)	S200 plunger | i/o pin



• When it comes to the guide-plate material, its mechanical characteristics (see Tech Note TN0019) will influence the CNC drill profile. This is important to ensure proper debris removal and flute cooling.
• Generally, your CNC machining operation should be able to determine the best spindle speed, feed rate, and peck pattern for drilling straight holes in different materials. However, if you encounter any issues, feel free to reach out to AlphaTest Corporation for suggestions. We're here to help.
10. What is the history of the MicroHELIX Series Test Probes?
• The MicroHELIX Series Test Probes were developed by AlphaTest Corporation as spring contacts for custom test probes and fixtures. These probes' unique construction allows for tighter pitch and closer centers in test sockets and fixtures. They were initially used in test fixtures and are now available in the electronic test and measurement industry. These microprobes have gained a reputation for quality and durability over the past 30 years.
11. How long does delivery take?
• Our catalog probes are either in inventory or can typically be delivered within 2 weeks. Custom probes that are not included in our catalog can generally be shipped within 3 to 4 weeks. Special probes, designed from scratch, may require 2 to 12 weeks. We can also build non-standard combinations from stock components, so please inquire if you cannot find the combination you need and can wait a few weeks.
12. What other made-in-the-USA products does AlphaTest Corporation offer?
• In addition to customizable probes with various lengths and tip configurations, we also specialize in building "difficult" fixtures and sockets for fine-pitch, small features, challenging topographies, and high-frequency applications. We stay up-to-date with market trends in testing and test probe requirements through our experience developing these made-in-the-USA products. AlphaTest Corporation also offers the hand-held μKELVIN™ fine-pitch Kelvin Test Probe, which measures low resistance values on various surfaces.
13. Do AlphaTest Corporation products comply with RoHS and REACH directives?
• Our manufacturing process involves machining and/or plating materials purchased from qualified suppliers. AlphaTest Corporation ensures that no hazardous substances listed in the RoHS and REACH directives are added or exposed to metals, plastics, or resins used in our products during assembly.
• We comply with Directive 2011/65/EU and Directive 2015/863/EU, which restrict the use of certain hazardous substances in electrical and electronic equipment.



Lead (Pb)	Polybrominated Diphenyl Ethers (PBDE)
Mercury (Hg)	Bis(2-ethylhexyl)phthalate (DEHP)
Cadmium (Cd)	Benzyl Butyl Phthalate (BBP)
Hexavalent Chromium (Cr VI)	Dibutyl Phthalate (DBP)
Polybrominated Biphenyls (PBB)	Diisobutyl Phthalate (DIBP)



• At AlphaTest Corporation, our products adhere to the EU RoHS Directives and do not contain excessive levels of restricted substances, as verified by our vendors. Please note that we do not independently verify vendor-provided certification, but we trust the accuracy of their information. Some of our custom test probes, fixtures, or sockets may contain RoHS-compliant solder.
• Regarding the REACH Directives, we assure you that our products do not contain any substances listed as Substances of Very High Concern (SVHC) in concentrations exceeding the Maximum Concentration Value (MCV).
14. What are the NCAIS and SIC codes for AlphaTest Corporation's products?
• All our products, including probes and fixtures or sockets, fall under the NCAIS code 334515 - Instrument Manufacturing for Measuring and Testing Electricity and Electrical Signals and the SIC code 3825 - Instruments for Measuring and Testing of Electricity and Electrical Signals.
15. How can I request a price quotation, place an order, or receive additional technical support?
• You have multiple options:
• Visit our Register page and leave a message.
• Send us an email at info@alphatest.com or
• Call us at 360 462-0201 during regular business hours: Monday-Thursday, 8 a.m.-5 p.m. and Friday, 8 a.m. to noon.