We will demonstrate the detailed steps for polishing a LC Hot Melt connector, including multimode and single mode LC connectors. The LC connector termination kit (6650-LC) is an extension to the basic FC,SC and ST connector termination kit(6365 and 6361). 6650-LC needs to work together with 6365 or 6361.But if you are terminating FC,SC or ST Hot Melt connectors, you only need 6365 or 6361(230 voltage version).

:: Tools needed for terminating 3M Hot Melt FC,SC and ST connectors

The 3M 6365(120V version) and 6361(230V version) universal Hot Melt connector termination tool kit provides all tools, test equipment and consumables necessary for terminating 3M FC, SC and ST Hot Melt connectors.

Here is the list of items in this tool kit

:: Tools needed for terminating 3M Hot Melt LC connectors (6650-LC)

:: 3M Hot Melt LC Connector Termination Steps Overview

1. Connector Preparation
2. Fiber Stripping
3. Inserting Fiber Into Connector
4. Connector Crimping
5. Fiber Scribing
6. Multimode Fiber Polishing
7. Single Mode Fiber Polishing
8. Connector Inspection
9. Put on Dust Cap for Stocking

Step 1: Connector Preparation

A. Turn on the 3M Hot Melt oven. The oven needs 6 minutes to warm up.

B. Remove LC connector from the package.

C. Attach LC Hot Melt holder handle to the load adapter with the slot aligned to the front.

D. Insert the connector into the hot melt connector holder

E. Place the load adapter, with slot aligned with handle, into an available port in the oven

F. Heat the LC hot melt connector for 75 seconds to 5 minutes

G. Place the heat shrink fixture in an available port in the oven

Step 2: Fiber Stripping

A. Place the strain relief boot first, then place the heat shrink crimp sleeve on the cable.

B. Place the jacketed fiber on the strip template. Mark the location of the jacket cut with a black marker on the cable. Then use fiber stripping tool 6365-CT to remove 33mm of fiber jacket.

C. Trim the aramid yarn to 5mm length.

D. Flare the aramid yarn evenly around the fiber buffer tube.

E. With 6365-CT fiber stripping tool, remove the 900um tight buffer in small pieces, until 22mm of 900um buffer tube is left. Now you should have about 11mm bare fiber at the front.

F. Clean the 11mm bare fiber with lint-free wiper moistened with isopropyl alcohol. The bare fiber should have no oil or acrylate coating debris.

Step 3: Insertion Fiber Into Connector

A. While the LC hot melt connector is still in the oven, insert the stripped fiber into the connector until it stops. Make sure that you are inserting the fiber into the fiber guiding tube at the back of the connector.

B. While still keeping the fiber’s position in the connector, push fiber jacket into the slot on the connector load adapter to secure the fiber cable. Keep the cable as straight as possible.

C. Now it’s time to remove the connector from the oven. While holding the connector holder’s cool-tough handle, remove it from the oven.

D. Place the connector holder into the cooling port on both sides of the oven. Leave it to cool for at least 3 minutes.

Step 4: Connector Crimping

A. Slide the heat shrink crimp sleeve towards the connector, covering oven the aramid yarn.

B. Remove LC connector from the connector holder.

C. With the 3M lettering facing to the left, crimp the metal  part of the heat shrink crimp sleeve once. You should use the crimp tool die labeled “A”.

D. Place the heat shrink crimp sleeve in the shrink fixture assembly for 10 seconds. The heat shrink tube should shrink snug around the fiber jacket. Rotate the fiber jacket when necessary in order to shrink evenly.

E. Slide the connector rubber boot over the crimp sleeve.

Step 5: Fiber Scribing

A. Hold the fiber scribe tool so the flat side of the blade faces down. Make sure the scribe blade is perpendicular to the fiber.

B. Score the fiber just above the adhesive bead by gently sliding the scribe blade across the fiber. You are only making a small scratch on the outside of the fiber, make sure you are not pushing too hard. The fiber should not break at this step.

C. Pull the fiber straight away from the fiber along the axis of the fiber. The fiber should break easily.

D. Now dispose the fiber scrap into a fiber disposal container.

Step 6: Multimode Fiber Polishing

A. Perform an air polish by holding the 9 micron lapping film firmly in one hand and gently moving the film in a circular motion for approximately 10 strokes or until approximately one half of the bead height is removed.

B. Using a lint-free cloth and isopropyl alcohol clean the connector after the air polish to remove all debris left by the 9 micron lapping film.

C. Clean the round polishing pad found in the 3M™ Universal Hot Melt Kit 6365/6361 with a lint-free cloth moistened with isopropyl alcohol.

D. Place several drops of alcohol onto the round polishing pad.

E. Before alcohol evaporates, place a sheet of the pale green 2 micron lapping film, shiny side down on the pad. The alcohol creates suction on the lapping film and helps hold it in place.

F. Clean the lapping film with a lint-free cloth moistened with isopropyl alcohol.

G. Clean the flat side of the polishing jig with a lint-free cloth moistened with isopropyl alcohol.

H. Place the polishing jig assembly on the lapping film.

I. Place the ferrule in the polishing jig aligning the latch side of the connector with the slot until it stops.

J. Insert the polishing weight into the adapter/jig assembly covering the connector.

K. Polish 10 figure-eight strokes or until bead of adhesive is no longer visible.

L. After bead of adhesive is no longer visible, polish an additional 5 strokes.

M. Remove the connector from the polishing jig assembly and clean the connector endface with a lint-free cloth moistened with isopropyl alcohol.

Step 7: Single Mode Fiber Polishing

A. Complete the multimode fiber polishing steps as in step 6.

B. Clean the gray rectangular polishing pad with a lint-free cloth moistened with isopropyl alcohol.

C. Place several drops of alcohol on to the rectangular rubber pad.

D. Before the alcohol evaporates, place a sheet of the 0.5 micron pale gray diamond lapping film on the polishing pad, shiny side down.

E. Clean the lapping film with a lint-free cloth moistened with isopropyl alcohol.

F. Place several drops of distilled water on to the diamond lapping film.

G. Insert the connector into the polishing jig assembly.

H. Clean the flat side of the polishing jig with a lint-free cloth moistened with isopropyl alcohol.

I. Place the polishing jig assembly on the wet diamond lapping film. Perform 3 to 4 figure eights.

J. Leaving the polishing jig assembly positioned on the lapping film, rotate 180 degrees. Perform 3 to 4 additional figure eights.

Step 8: Connector Inspection

A. Inspect the connector endface with the 200X fiber optic inspection microscope. Use the thumb toggle switch to activate the light onto the fiber end face.

B. Good polish picture

C. Bad polish picture

Step 9: Connector Stocking

If connector is not to be immediately put into service, install the protective dust cap.

Those epoxy and polish connectors are reliable, cheap and has been industry standardized. Big manufacturers terminate thousands or even tens of thousands of epoxy and polish connectors each day.

However, these standard connectors are not suitable for all applications, especially in the field. Emergency recovery and low quantity field terminations require quick and easy approaches for fiber optic connector termination. That is where the quick termination connectors such as 3M Hot Melt, 3M Crimplok, Corning Unicam, Tyco/AMP Lightcrimp Plus and the newly introduced 3M No Polish connectors come to play.

What characteristics do these quick termination connectors have in common? Quick, low tool cost and easy to master. Although each type has its own design characteristics, quick and easy are what make them different from the traditional epoxy and polish fiber connectors.

Traditional connectors cost as low as 2 bucks each while the quick termination connectors typical cost from $7 and above. But traditional connectors require polishing machines that cost $5000 or even more, while quick termination connectors only require tools that cost less than $1500 or even only hundreds of dollars.

However, the big concern most fiber optic technicians and engineers have is whether they provide the same long term reliability, low insertion loss and back reflection as the good old epoxy and polish connectors. That is what this article is all about.

We are presenting the 3M Hot Melt connector reliability technical report here. This is the first in a series of reliability report on quick termination connectors. Keep tuned and we will follow this with reports on 3M Crimplok, Corning Unicam, Tyco/AMP Lightcrimp Plus and 3M No Polish connectors.

The Conclusion?

3M Hot Melt fiber optic connectors meet targeted requirements.

The test results showed consistent low insertion loss, environmental stability and physical robustness of 3M Hot Melt connectors. When properly installed, the connector provides a reliable voice and/or data transmission circuit.

A series of optical, environmental and mechanical tests were conducted which exposes them to conditions more severe than those anticipated in actual use. The tests were in accordance with TIA-568.

Four groups of new 3M Hot Melt ST connectors were tested. Here is the test setup.

1. New Product Test Result

30 pcs of 3M Hot Melt ST connectors were cleaned and tested under room temperature 22°C. Their insertion loss and back reflection were recorded as below.

2. Environmental Test (Group 0)

2.1 Low Temperature Storage Test (10 samples, -10°C)

The 10 samples were put in a -10°C chamber for 96 hours. Insertion loss and back reflection were tested at the start and finish at 22°C.

Insertion Loss Test Result

Back Reflection Test Result

2.2 High Temperature Storage Test (10 samples, 60°C)

Those 10 samples, after finishing the cold test from above, were then put into a 60°C chamber for 336 hours storage. Measurements were made at the start, in the process and at finish.

Insertion Loss Test Result

Back Reflection Test Result

2.3 Humidity Test (10 samples, 40°C, 90~95% Relative Humidity)

Those 10 samples, after finishing the temperature life test from above, were then put into a 40°C, 90-95% Relative Humidity chamber for 96 hours.

Insertion Loss Test Result 

 Back Reflection Test Result

3. Mechanical Test (Group 1)

3.1 Impact Test (10 samples)

10 pcs of 3M Hot Melt ST connectors were fixed in a impact test fixture. These connectors were then raised to the horizontal position and released to strike a concrete block. The impact was repeated 8 times and then the connectors were tested.

Test Results After Impact 

3.2 Flex Test (10 Samples)

Those 10 connector samples, after finishing the above impact test, were fixed onto the swing arm of 3M Flex Tester. A 0.5kg load is attached to the cable 25cm from the pivot point. The connector is then cycled through 0°, +90°, 0°, -90°, 0°, about the center axis of the connector for 100 cycles. Measurements were taken after the flex test.

Test Results After Flex Test 

3.3 Twist Test (10 Samples)

Those 10 connector samples, after finishing the above Flex test, were fixed to the swing arm of the 3M Flex tester and the swing arm is locked in the 0° position. A 15N (3.3lbs) load is attached to the cable 25cm from the pivot point. The weight is rotated about the cable axis 2.5 revolutions in one direction, reversed for 5 revolutions, and reversed for 5 more revolution for a total of 10 cycles.

Test Results After Twist Test