(Part I)


 Anatomy of Impact Mount™ technology

Overview

 In a nutshell, this technology employs a mechanical spring-loaded center punch whose sharp point was replaced by
a hollow conically shaped die to cause a displacement of the material of the ferrule symmetrically towards the ferrule's axis
therefore creating a friction force on the optical fiber called fiber retention.

The method is described in detail in the US patent # 5,305,406 issued on April 19, 1994.
The application for this patent was a continuation-in-part of an earlier application that resulted in issuance
of the US patent # 5,216,735 on June 01, 1993.

 It is a misconception that any method of holding a fiber in a metallic ferrule using a friction from deflection of the material
of the ferrule is covered by the term "Impact Mount"™ technology (IMT)or protected by Valdor's patent.
 There are other methods of creating fiber retention utilizing a mechanical friction between a metallic ferrule and a fiber
disclosed publicly before the issuance date of the US patent # 5,305,406. In fact, there is an entire subclass within the Optical
Waveguides class, that the USPTO reserves exclusively for cases where a fiber is secured within the ferrule by applying
mechanical pressure from crimping and similar methods.

 Another misconception is that IMT™ is the only method using dynamic force or "IMPACT" to accomplish the task of
securing a glass optical fiber within the metallic ferrule by causing a displacement of the ferrule's material.
 There is written documentation dated long prior to Valdor's application date explicitly suggesting using an "IMPACT" to secure
a fiber within the ferrule. So, any suggestion that "any one who wraps metal around the fiber using a dynamic force
or IMPACT will infringe with Valdor's patents" is at the very least misleading.
 It seems that Valdor's trademarked phrase: Impact Mount™ technology, in combination with the patent
on the tool accomplishing the task (see US patent # 5,305,406) was a clever and effective strategy for securing
their past marketing success.

 An interesting note relating to the IMT™ was an April 8, 2008 announcement made out of Toronto
by Aspire International and posted on Reuter's News at 8:03 AM. According to this announcement there is an additional
individual claiming co-inventorship of Impact Mount™ technology.
 The unmentioned in any related patents co-inventor is Dr. Shin-Lo Chia - a former Vice President of EZcon Corporation
in Taiwan. The announcement says:
"Dr. Chia also held various management and consultant positions in many other companies. He holds U.S. patents in optical attenuator and is one of the inventors of the VALDOR Impact Mount Technology (http://www.valdor.com)."
The full text of the announcement can be viewed (!!) - Here

Links to information about IMT™ on the Web

There are only a few articles written "explaining" this method of holding the fiber within the connector's ferrule.
Below are three that contain most of the relevant information.

(1) - Here an article by Michel Rondeau Ph.D. published in Laser Focus World in 1995

(2) - Here a very brief description of IMT ™ presented on the Valdor's current web page

(3) - And here a much broader article written jointly by M.Y.Rondeau, Ph.D. and E.Palen, Ph.D.
titled "A Silver Bullet: Impact Mount Technology" and published in MEPTEC Journal in 2002


Straight from the horse's mouth
  or
The power of persuasion

 In all available material related to IMT™ written by Valdor or independent experts there is rarely mention of the actual
effects of the impact process on the material of the ferrule. Rather, it is simplified or even trivialized, by suggesting that
the movement of the material is only causing a reduction of the aperture in the ferrule containing the fiber thus creating
a significant retention.
 The supporting illustrations tend to be very symbolic and in some cases do not support some of the statements
made in the text. For example, the illustration on Valdor's web site (see: this link ) suggests - at least symbolically
- that the impact die is actually a regular cylinder. Confusing?

In the promotional article in Laser Focus World from 1995 the author Michel Rondeau Ph.D.says:

"Because of the cold-flow properties of the ferrule, the fiber can be undersized by as much as 25% of the opening; thus, one size of connector can accomodate many different fiber sizes. Only a few different sizes of connector are necessary to span fiber diameters ranging from 125 to 2000 μm."
Reeeeally ?
 Does it mean, we can take a ferrule, with a hole of 166.6 μm diameter and securely install a 125 μm fiber?
To verify the above statement, we tested it, using the values for the tool settings recommended in past to the customers
and tested it, and tested it, and ..... - sorry - no success.

In the same article near the end of it the author says:

 "FIGURE 2. Impact mount tool dynamically applies uniform
 force around the full length of a metal ferrule."

 In the standard ST FC and SC type of connectors the "full length of the metal ferrule" is approximately 8.0 mm. or
about 0.315". This would mean that the Impact Mount™ technology is capable of creating a force along the length
of 8.0 mm. Very impressive.
 In real life the length of contact of an optical fiber within the ferrule is only a few hundred micrometers.






This photo shows the impact die
in contact with the ferrule of the
connector in the position after
the impact.
The impact caused a cold flow
of the material of the ferrule's tip
only on the length of approximately 0.350 mm.
In fact the entire length of the 127 μm
hole - in the standard ferrule - that
accepts the fiber is about 0.5 mm.

 There is no doubt that claims similar to those above, along with the past representation of the scope of patent protection
(at least to some investors), may still attract the attention of new investors unwary of specific details regarding this process.


The Devil is in the details or How does it work
 (ferrule / impact die interaction)

 Us patent # 5,305,406 explains the method only in general.
 It does not elaborate on the direct effect of the process on various components of the system that includes specifically
the frontal portion of the ferrule that is in direct contact with the impact die.
 As the energy of the impact is being released at the edge of the tip of the ferrule, the material of the ferrule adjacent
to the surface of the contact between the impact die and the ferrule is forced essentially in three directions affecting three
distinct regions of the tip of the ferrule.

Region #1 - Normal to, and towards the axis of the tip of the ferrule,
Region #2 - Forward of the ferrule,
Region #3 - Normal to, and away from the axis of the tip of the ferrule.

(See the photo below.)


Region #1

 As the impact die travels, from the initial contact with the ferrule until it finally comes to rest, the hole surface gradually
grips the fiber deeper toward the back of the the tip of the ferrule.
 Also, as the impact die continues its movement the surface area of its contact with the ferrules tip increases and the speed
of the movement decreases.

In consequence, the force of the grip along the total length of the hole at which the fiber is being held is not expected
to be uniform but is expected to be decreasing with depth.
The forces acting on the fiber and their distribution within the Region #1 are responsible for the total value of the fiber retention.

Region #2

 At the very beginning of the process of the displacement, the material is being forced away from the tip of the ferrule in the direction opposite to the movement of the impact die finding the path of least resistance to the flow.
 After the hole is totally closed around the fiber at the immediate proximity of the front of the tip of the ferrule even more material is being displaced. The flow of the material in this direction continues until the impact die completes it's travel.
 This creates a well defined "crater" with sharp edges at the tip of the ferrule. What used to be the flat surface of the tip
of the ferrule now is a highly wrinkled, concave feature.
 There is reason to suspect that this wrinkled surface also stores some of the energy of the impact (similar to the spring),
acting away from the edge towards the center and contributes to significant increase of the force of the grip
of the fiber, but only at the end of the hole and is a major component of the total gripping force acting upon the fiber.
 The formation of Region #2 has a significant influence over the final quality of the mounting process.

This will be discussed in detail in Part II of the "Anatomy of Impact Mount™ technology".

The photographs below show the shape and texture of the surface at the Region #2.
To view in full size click on the photograph.


Region #3




 As the impact die travels toward the back of the ferrule's tip it attempts to push some material in the same direction.
As a result a minute amount of material, choosing the path of least resistance, creates a slight bulge away from the surface which increases the tip's diameter.
In applications that utilize a ferrule with a reduced tip diameter, this is of little importance.
 However, in applications that rely on the ability of the tip of the ferrule to be accurately mateable with the tip of another
ferrule in a common sleeve - it may become a major concern. The ferrule/impact die area is only one component
of a much larger system. Each component of this system (and their variables) plays a role in obtaining a reliable and
repeatable mounting effect.

 The details of these components, their interaction, and their influence on the fiber retention, will be discussed further
in Part II of the "Anatomy of Impact Mount™ technology".

 In Part III of the "Anatomy of Impact Mount™ technology" we will focus on issues specific only to IMT™ and
relating to cleaving (both: automatic and manual), as well as polishing.










Copyright   ©   2008, Duracon inc.
Impact Mount Technology is a trademark of Valdor Fiber Optics Inc.