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Microscope parfocal and clean up

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So what is Mirciscope Parfocal and why does it matter? To make it simple if a compound microscope is parfocal, it means that when you change magnification ( 4x to 10x to 40x to 100x), it will only require a very small turn of the fine focus knob with each increase or decrease to get the image in focus. Note, this is only true in sequence. For example, if you go from 4x directly to 100x, the image will no longer be in focus and will require greater adjustment.

It means something slightly different for a stereo microscope. If you get a sample in focus at the highest magnification on a parfocal instrument, you will then be able to zoom out to any lower magnification and the sample will remain in focus.

Microscope cameras are parfocal if both the camera image and eye piece image are in focus simultaneously.  Some camera mounts actually have a focus adjustment to achieve this. (If your camera image is not in focus, check to make sure the eye pieces are set to zero)

This matters because Microscope lenses can easily be scratched and should be treated with great care. Never use sharp instruments or anything abrasive to clean the microscope lens. To clean the microscope eyepiece  or the microscope objective lens , moisten lens paper with lens cleaning solution and clean the lens with a circular motion. You can dry the lens with a clean, dry piece of lens paper and when you are finished use an aspirator to remove any lingering dirt or particles.

To determine if your microscope eyepieces need cleaning, loosen the small set screw for the eyepiece (if there is one) and rotate the eyepiece in a circular motion while looking through the microscope. If there is a dust particle that rotates as you rotate the eyepiece, remove the eyepiece from the microscope and clean both sides of the lens with lens paper. If you need to use any liquid for cleaning, distilled water is recommended. It is not recommended that you take the eyepiece apart, as there are generally multiple lenses in the eyepiece and they can be difficult to put back together in the correct order.

Soldering tip life training

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Even under normal usage, the plating on all soldering iron tips will eventually fail. Plating life is highly dependent on the soldering application, the type of fluxes and solder used, and—most importantly—operator technique. Because of this, manufacturers of soldering iron tips do not generally warrant plating life. Tip plating failures for all solder tips can be divided into three main classes. • Stress/Cracking • Corrosion • Wear/Abrasion . To help avoid these tip failures let me give some advice and tips 

Cracking:  Select the largest tip possible for the lead being soldered.  Dont apply excessive pressure when soldering. To maximize heat transfer, tin the tip.

 Take care not to bang the solder tip against the metal workstand when inserting the tool.  Do not use tips as a screwdriver or a prying tool.

 

 

Wear: • Select the largest tip possible for the lead being soldered. Blunter tips carry more plating. Do not apply excessive pressure during soldering. or "scrub" the lead. To maximize heat transfer, tin the tip and create a solder bridge. Dont drag solder. If you must drag solder be aware that it will shorten tip life. avoid using commercial tip tinners for routine tinning instead Use a flux core solder wire or paste. Use a clean, wet sponge to clean the tip not a dry sponge, rag, or any abrasive.

 

Corrosion: Select lower activity fluxes where possible; RMA flux is best for maximum tip life.  Use only sulfur free sponges for cleaning tips. and clean sponges.   Use RMA solder to tin tips during storage. Do not use high activity flux solders.

Dewetting: Turn the system off when not in use. Use the lowest possible temperature when soldering since low temperature reduces oxidation.  Keep tips tinned when in use and during storage as this keeps air from the tip.  use a flux with suitable activity during soldering. Use only clean sponges. Use deionized water to wet the sponges.  Use the lowest possible temperature. Low temperature reduces thermal oxidation, solvent volatilization, and polymerization.  Periodically use an RMA wire solder or solder paste to tin the tip.

Heater Care: Do not use pliers to change tip cartridge  instead use a Cartridge Removal Pad. Do not drop tip cartridges onto hard surfaces.  For surface mount tips and dont bang the tips to dislodge components. Use a sponge.

ESD Basics Training

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So some basic facts:  ESD or an electrostatic discharge  is the sudden transfer of static charge between bodies at different charge potentials caused by near contact or induced by an electric field. Now ESD matters because a lack of ESD control can lead to electronic parts being “zapped” leading to:  Failed parts plus Increased costs as well as wasted time , missed deadlines and an unhappy team

One of the most common causes of ESD damage is the direct transfer of electrostatic charge from the human body or from a charged material to the ESDS item. When one walks across a floor, an electrostatic charge accumulates on the body. Simple contact (or even close contact) of a finger to the leads of an ESDS item allows the body to discharge, possibly causing device damage. The model used to simulate this event is the Human Body Model (HBM).

The Human Body Model is the oldest and most commonly used model for classifying device sensitivity to ESD. The HBM testing model represents the discharge from the fingertip of a standing individual delivered to the device. It is modeled by a 100 pF capacitor, which is charged by a high-voltage supply through a high-ohmic resistor and then discharged through a switching component and a 1.5 kW (1,500 ohms) series resistor through the component to ground or to a lower potential. 

ESD Testing

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 ESD testing is the process of checking a device’s resistance to electrostatic discharge. Known to be caused when two electrically charged objects come into contact with one another, there is a sudden flow of electricity creating a visual spark or discharge. While they are not lethal on their own, the sudden release of energy renders devices and equipment dysfunctional.

ESD testing is an electromagnetic compatibility test (EMC test). ESD testing simulates various electrostatic impacts that equipment might experience either during transit or operation. An electrostatic discharge test determines whether a product is in compliance with its ESD protective area and procedures.

ESD can be transferred through the air or contact. The most common test of ESD is called human body method (HBM). The test simulates the effect on an electronic component of a human discharging electrical energy onto it. This energy is a static buildup.

There are two ESD test methods. One is the air method and the other is the contact method. The air method ESD testing involves moving a charged generator or discharge object such as an ESD gun towards the device being tested. There are many variables that can impact ESD testing. These include humidity, the speed of the discharge object towards the test device and temperature. ESD events are much more common in low temperature and low humidity environments.

The contact method ESD testing helps eliminate the impact of environmental effects such as temperature and humidity. This test method involves an ESD generator being in direct contact with the device to be tested. This contact is in place throughout the entire test. While this test method is generally consistent across environmental conditions, contact ESD rarely occurs naturally.

An ESD test confirms that the equipment correctly operates per the test requirement and the manufacturer’s operating procedures. ESD testing is generally part of a larger EMC test plan for product certification compliance.

 

 

Ionizer Checkup

The best way to keep electrostatic sensitive devices (ESDs) from damage is to ground all conductive objects and remove insulators from your ESD Protected Area (EPA). This is not always possible because some insulators are process-essential and are necessary to build or assemble the finished product. The only way to control charges on these necessary non-conductive items is the use of ionization systems.

However, if an ionizer is out of balance, instead of neutralizing charges, it will produce primarily positive or negative ions. This results in placing an electrostatic charge on items that are not grounded, potentially discharging and causing ESD damage to nearby sensitive items.

It is therefore essential to regularly clean your ionizers and verify they function correctly. Below we have put together a list of tasks you need to perform with your ionizers on a regular basis.

Under normal conditions, an ionizer will attract dirt and dust (especially on the emitter points). To maximize neutral efficiency and operation, cleaning should be performed on a regular basis.

Wipe the case with a soft cloth and deionized water. Fully squeeze the wiping cloth or sponge to remove any excess liquid. If a stronger cleaning solution is required, use a soft cloth with mixture of isopropyl alcohol and deionized water (70% IPA and 30% DI water).

The emitter points should be cleaned using specific emitter point cleaners or a swab dampened with Isopropyl alcohol. Below are general instructions on how to clean emitter points. However, each unit is slightly different so always refer to the ionizer’s manual.

Turn the unit OFF and unplug the power cord. Open the top screen by loosening the screw and swinging the grill to one side.Clean the emitter points using the an emitter point cleaner or a swab dampened with Isopropyl alcohol.Re-attach the top screen and Plug in the power cord and turn the unit ON. Steps are going to be from left to right at the bottom

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APR Calibration

A calibration kit consists of precision standard devices that are used to characterize systematic errors of network analyzers. APR Thermal Calibration Kits include everything needed to perform thermal calibrations. Thermal calibrations are recommended annually and anytime maintenance is performed to the machine's heating elements. Here are some models

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