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Yield/Reliability Problem – Analog Integrated Circuit
Inventive Problem Solving Case Study


EXECUTIVE OVERVIEW:
Introduction
Technological Challenge
Responding to the Challenge
Business Issues
Problem Background
Innovation, Design, and Development within the Company
Defining the Business Opportunity
Meeting the Challenge
Economic Impact
DETAILED CASE STUDY:
The Ideation Problem-Solving Process
Step 1: Innovation Situation Questionnaire
Step 2: Problem Formulation
Step 3: Prioritize Directions and Generate Preliminary Ideas
Step 4: Develop Concepts
Step 5: Evaluate Results

EXECUTIVE OVERVIEW

Introduction

Project Name: Positioning of SO-8 contactor in high volume, high-speed test equipment

Corporate Information:

COMPANY NAME: "XYZ Company"
HEADQUARTERS: Silicon Valley
LOCATIONS: Europe, Asia, US
NUMBER OF EMPLOYEES: 12,000
CORPORATE SALES: $2 Billion
PRODUCTS: Mixed Signal Analog & Digital Components

Business Focus:

LOCATION: Silicon Valley
NUMBER OF EMPLOYEES: 120
SALES: (Confidential)
PRODUCTS: Power Management
MARKET: Personal Computers, Notebooks and Work Stations; Multimedia; PC Communications; Wireless Communications; Monitors/Displays; Fax Machines and Scanners; Power Management; LANs and WANs; Automotive; Consumer; Military/Aerospace
BUSINESS UNIT NAME: Division of XYZ

Technological Challenge

Develop a contactor system to allow automated testing of a highly sensitive analog integrated circuit in a Small Outline 8-pin (SO-8) molded plastic package.

The specific device that drove this challenge is an analog integrated circuit. When the integrated circuit is being tested by Automated Test Equipment, it is required that certain external components be placed immediately adjacent to the device’s leads. This close-in condition is necessary because the part is unstable without the compensating components, and the parasitic reactance of these components and the associated environment must be minimized. This can be done only by placing them as close as possible to the device leads. Even a separation of as little as 3 mm may be too great to allow stability to be maintained. Without stability, it is impossible to measure and test the device.

The traditional approach to testing integrated circuits in this same package relies on a socket, and at times an additional cable, which separates the device under test from any auxiliary circuitry by a meter or more. This was clearly impossible to use in the case of the device to be tested. An innovative solution was required.

Responding to the Challenge

Utilize the Ideation Problem-Solving Process (facilitated by Dana Clarke of Ideation International) to attack the SO-8 Contactor Problem as a part of workshop and training session. Seven test development engineers, four of which were currently involved in the contactor project, attended the workshop.

In the course of the workshop, members utilized the Innovation WorkBench System (IWB) software to describe the problem in detail, look for the resources, formulate the problem, develop and prioritize Directions for Innovation, and review applicable Operators and illustrations of innovative solutions from many disciplines. The IWB software also provided a means for documenting the problem-solving process as it was carried out. Many ideas were offered and recorded, as were associated secondary problems that occurred to the engineers as the ideas were discussed.

Business Issues

STRATEGIC: Directly related to needs of new customer

COMPETITIVE: Customer had just been taken from competitor

ECONOMIC: $10,000,000 business opportunity

Problem Background

The Division of XYZ test development engineers responsible for developing the test solution for this device considered the problem and concluded that no solution available in-house, or known to exist off-the-shelf, would be adequate. Accordingly, the test development engineers decided to contract with an outside vendor, ABC, which specializes in test contactor technology. ABC consists of two experienced and skilled engineers who have a good track record for developing high- performance contactor solutions for the semiconductor manufacturing market.

In collaboration with the ABC engineers, at least two, and at times as many as five, Division of XYZ engineers worked toward a solution for the contactor problem. This project was underway for approximately five months prior to the Ideation/TRIZ training session. During this time, $40,000 was paid by Division of XYZ to ABC for development of the contactor and for actual hardware which was delivered and installed. Also, as much as 12 man-weeks of Division of XYZ test development time (at roughly $3,000 per man-week) were devoted to this project. The total expense to Division of XYZ was somewhere in the range of $76,000.

At the end of this five-month period, the performance objectives of the project had not been fully met. A contactor design had been developed, implemented, installed, and tested. In fact, five iterations of design changes had been made, and problems still remained. The specific problems with the Division of XYZ/ABC contactor were an unacceptably high jam rate (%1) and an unacceptable rate of false continuity failures (1%). A jam is when a part fails to disengage from the socket after being tested and must be manually dislodged. A false continuity failure is a condition where the device under test fails to make adequate electrical contact with the contactor on one insertion, but may pass on a second insertion. (In other words, the continuity test fails even though there is nothing wrong with the device).

The design of the Division of XYZ/ABC contactor (see FIGURES 1 and 2) consisted of a set of very small beryllium copper fingers shaped into a spring configuration and supported by a shape made of elastomer. All of this was supported in a stainless steel frame mounted to a multilayer printed circuit board (PCB). The device under test is pushed against the contactor fingers by a pneumatically operated insulating (teflon-impregnated nylon) plunger. The device-loading rail and the plunger are integrated into one assembly, and the contactor, mounted to its PCB, is rigidly attached to the rail-plunger assembly. The critical close-in components are actually embedded in the contactor frame, immediately adjacent to the contactor fingers. This provides a total path from device lead-to-external component spacing on the order of 1mm. Also, TEM (transverse electromagnetic field) techniques are used in the layout to achieve zero inductance paths to decoupling capacitors.

Key for Figure 1:

1 - Analog Integrated Circuit
2 - Printed Circuit Board
3 - Plunger
4 - Rail
5 - Singulator
6 - Stop pin
7 - Close-in Components

FIGURE 1

Key for Figure 2:

1 - Printed Circuit Board
2 - Close-in Components
3 - Beryllium Copper Fingers
4 - Fibrous Elastomer Sheet

FIGURE 2

 

The problems with the Division of XYZ/ABC contactor solution which were encountered in acceptance testing were determined to be associated with the backing of the contactor fingers, as well as with the contact fingers themselves.

First (see FIGURE 3), the backing of the contactor fingers consisted of a woven, or fibrous, elastomer sheet. As the contactor was used to contact a number of parts, the fibers of this sheet were becoming dislodged and creating a slightly "fuzzy" surface, with fibers protruding up a short distance from the elastomer sheet. This was sufficient to occasionally snag the leads of the device under test, preventing it from easily (i.e., under the force of gravity alone) separating from the contactor fingers and exiting the contactor. Repeated tapping of the contactor was required to dislodge the device, and often the contactor had to be disassembled to remove the stuck part.

FIGURE 3

The second problem area (see FIGURE 4) was a continuity problem with certain fingers on the contactor. This was tentatively attributed to a tendency of some of the fingers to move laterally during repeated contacting. The fingers were required to be fairly flexible in the vertical dimension, but rigid in the side-to-side dimension. However, after repeated contacting of devices, some of the fingers were observed to have shifted, deformed, or rotated in the horizontal plane. This led to slight misalignment with the leads of the device under test, and possibly caused the continuity problem which was observed.

FIGURE 4

Innovation, Design, and Development within the Company

In general, there is no formal creativity or inventive problem solving skills training within Company XYZ.

The engineers involved in the Ideation/TRIZ workshop all had extensive experience in semiconductor testing, including handler and contactor issues. An exception to the corporate environment, all of them had received de Bono’s Six Hats training. In addition, all but one had also been trained in de Bono’s Lateral Thinking. The engineers had applied the de Bono methods to this problem for several months. All of the engineers in the workshop participated in the discussions with Ideation trainers and contributed in working with the Ideation Problem-Solving Process.

Defining the Business Opportunity

The Market Opportunity for a properly performing system is $2,000,000.

Meeting the Challenge

The problem of the laterally moving fingers and the problem of the sticking parts were both looked at using the Ideation Problem-Solving Process in detail. Considerable time was spent (using Anticipatory Failure DeterminationTM) in describing how the contactor fingers could be made to move laterally, and what would be required to counteract this lateral movement or deformation.

One trend became apparent – a movement toward ideality in the design of the contactor. A characteristic of the Division of XYZ/ABC contactor solution which had become clear was the relative complexity of the solution – there were many tiny parts which had to be very carefully fabricated and aligned, and kept in alignment during extended operation. This was proving to be very difficult. It was believed that a reduction in parts, or a simplification in design, would produce a better-behaved contactor.

In considering the sticking part, several examples were suggested by various paths of inquiry using the Innovation WorkBench System (IWB) software. One idea involved using a "puff" of air to dislodge the part, but this involved the development of additional hardware and control devices. Another idea suggested a spring, which would be compressed by the device package as the plunger pushed the device against the contactor fingers, which would then drive the device apart from the fingers when the plunger retreated. This idea was eventually developed into a Solution Concept entailing a "dot" of elastic polymer, which could be placed in the middle of the contactor floor to act as a spring. This was believed to be a workable and elegant solution to the problem of sticking parts.

Part of the complication of the contactor solution implemented using copper fingers was caused by the necessity to split several of the contacts into two parts at each contact point in order to allow Kelvin contacting (thus allowing both current force and voltage sensing for precision measurements). Many ideas were discussed as to how to overcome the problems caused or exacerbated by the Kelvin contact requirement.

Gradually, the concept of eliminating the fingers+elastomer design in favor of a more direct solution grew from an individual idea into a Solution Concept. It was suggested that the fingers and elastomer support be removed entirely and replaced by a conductive elastomer sphere attached directly to the PCB pad. The sphere would contact the device lead directly and convey the contact to the PCB pad. The elastomer sphere would be both highly conductive and elastic (compressible). This would provide a low resistance circuit path to the device under test, and the elasticity would provide a mechanically even resistance to the force of the plunger against the device. This, in conjunction with the elastic dot pressing against the middle of the device package, would also provide for positive disengagement of the device upon completion of the test procedure.

These two Concepts, both of which were generated and evaluated during the workshop, were regarded by all of the Division of XYZ test development engineers present to be an innovative and viable solution to the problems of the existing contactor. Moreover, it was believed that the two ideas could be developed into a suitable solution to the challenge posed not only at the beginning of the workshop, but by the contactor project itself. It was the opinion of all involved that the Ideation Problem-Solving Process made the attainment of these two concepts much easier and quicker than expected. In fact, without these concepts, the project undoubtedly would have continued on an uncertain course of incremental improvement to the existing solution. What was obtained by the session using the Ideation/TRIZ Methodology allowed a more ideal and innovative solution to appear.

When compared to the amount that had already been invested in the project (approximately $76,000) without achieving satisfactory results, the outcome of the Ideation Problem- Solving Process could be considered as highly productive and resulting in a significantly reduced time-to-market.

Economic Impact

The economic impact is losing a $2,000,000 market opportunity plus the loss of a new customer that was displaced from the arms of a competitor. Customer potential is approximately $10,000,000 including add-on business.


DETAILED CASE STUDY: The Ideation Problem-Solving Process

Step 1: Innovation Situation Questionnaire

¨ 1. Describe your problem briefly, using free-style wording

Devices jamming in contactor, having high failure rate for continuity, and not being robust for manufacturing

¨ 2. Apply the "Ideal Vision Approach"

Ideality would assume that the device does not need to be tested. This however, is not possible at this time. The next vision of ideality is that we are able to test the device by itself. This also is not feasible at this time. Going down further, the device should be able to be tested with a system that allows for special electrical performance needs to be met without compromising the mechanical interconnect needed, without jamming at all in manufacturing and not having any false failures due to the mechanical or electrical interface needed.

¨ 2.1. Substance resources

Scrapped parts that are good (can be retested)
Scrapped parts that are bad (can be retested)
Tape can fray
Socket can be scrapped ($700 per)
Money resources are wasted
Air
Air motion
Parts
Mechanical movement
SO (small outline) – leads (copper-based, tin-lead coating), plastic molding (boron silicate, plastic filler)
Teflon tape
Beryllium-copper springs
Elastomer – fiberglass with goop
PC board gold contacts
Plunger block (teflon-impregnated nylon)
PC board
People
Spring-loaded contact (Kelvin and non-Kelvin contacts)
Upper spring action
Lower spring action
Taped portion of the spring
Glue in elastomer
Plunger function of forcing part leads onto contacts

¨ 2.2. Field resources

Mechanical (spring action, gravity, air flow, lateral motion & vertical movement of fingers)
Thermal (ambient temperature)
Chemical
Electrical (electrostatic charges)
Magnetic
Electromagnetic

¨ 2.3. Functional resources

Spring actions
Movement
Electrical conductivity
Stickiness of tape
Lateral motion
Downward force of plunger and SO
Elastomer has spring action
Plunger action cause vibration
Plunger action compresses pins
Spring rotation of elastomer to fingers

¨ 2.4. Space resources

Vertical and horizontal space resources around SO-8 package
Space between fingers
Space between leads
Space between package and elastomer
Spatial changes related to positioning of package and movement of leads

¨ 2.5. Time resources

Time of positioning SO-8 package
Time before positioning
Time of depression of springs
Time of test (idle time)
Time after test
Time of removal of SO-8 package
Time when spring tension is relieved

¨ 2.6. Informational resources

Spring tensions
Spring flow
Elastomer board flow
Current flow
Information related to positioning and control of position
Mechanical strength and degradation of fingers
Aging of elastomer

¨ 3. Worst possible consequences if the problem is not solved

Short contact life – over rejection for continuity
Not able to release to manufacturing because not robust
Loss of business opportunity
Loss of new customer

¨ 4. Express approach: consider appropriate typical problem(s)

Not applied

¨ 5. Consider the "bypass" ways to resolve the problem

Reduce or eliminate a harmful action:

  • Reduce the sensitivity of the entire system to the jamming of the devices and the high false failure rate.

  • Remove from the system those elements that are sensitive to the jamming of the devices and the high false failure rate.

  • Improve the process features so that the jamming of the devices and the high false failure rate becomes insignificant, and thus avoid the need to solve the problem.

  • Consider an alternative principle of action for the system that avoids the jamming of the devices and the high false failure rate.

  • Try to cope with the jamming of the devices and the high false failure rate, and use resources to compensate for its results.

  • Develop the next generation of the system so that the jamming of the devices and the high false failure rate does not occur.


Step 2: Problem Formulation

¨ 1. Zoom into the problem

¨ 1.1. Desired improvement or a drawback to be removed
Prevent lateral movement of contact leads without adversely affecting the function – flexible enough to make contact on a spring action but strong enough that it will not have any lateral movement.

¨ 1.2. Mechanism causing the problem
Initially unknown. AFD (Failure Analysis) used to develop consensus that the mechanism causing the problem was different forces being applied to different contact points

¨ 1.3. What requirements or conditions made the problem critical?
The primary requirement is the manufacturing need for robustness and no false failures.

¨ 2. Zoom into the system where the problem occurs

¨ 2.1. System name
Handler contact

¨ 2.2. System structure
(See Figures 3 and 4)
– handler (rails, singulator)
– contact block
– test board
– part
– tester
– plunger

¨ 2.3. Primary Useful Function
Bring device to test board

¨ 2.4. Dynamic functioning of the system
—
part comes down handler rail to contact block
— singulator pushes part into contact site
— part hits stop pin
— plunger pushes part to contact fingers
— part is electrically tested
— plunger returns to nominal position
— stop pin is lowered
— part is sorted into appropriate bin

¨ Problem Formulator Diagram

¨ 3. Basic Directions for Innovation*

  1. Find an alternative way to obtain the (Plunger pushes part into contactor), that provides or enhances the (Contact pressure), but does not cause the (Contact finger lateral movement), and does not require the (Proper positioning of SO package).

  2. Find a way to enhance the (Plunger pushes part into contactor).

  3. Find a way to resolve the contradiction: the (Plunger pushes part into contactor) should exist to obtain the (Contact pressure), and should not exist in order to avoid the (Contact finger lateral movement).

  4. Find a way to do without the (Plunger pushes part into contactor) for obtaining the (Contact pressure).

  5. Find an alternative way to obtain the (Proper positioning of SO package), that provides or enhances the (Plunger pushes part into contactor) and (Contactor fingers push up against part leads).

  6. Find a way to enhance the (Proper positioning of SO package).

  7. Find a way to do without the (Proper positioning of SO package) for obtaining the (Plunger pushes part into contactor) and (Contactor fingers push up against part leads).

  8. Find an alternative way to obtain the (Stop pin retracts), that provides or enhances the (Part falls into shuttle).

  9. Find a way to enhance the (Stop pin retracts).

  10. Find a way to do without the (Stop pin retracts) for obtaining the (Part falls into shuttle).

  11. Find an alternative way to obtain the (Part falls into shuttle), that provides or enhances the (Successful SO package test), and does not require the (Plunger retracts) and (Stop pin retracts). This way should not be influenced by the (SO package jams).

  12. Find a way to enhance the (Part falls into shuttle).

  13. Find a way to protect the (Part falls into shuttle) from the harmful influence of the (SO package jams).

  14. Find a way to do without the (Part falls into shuttle) for obtaining the (Successful SO package test).

  15. Find an alternative way to obtain the (Electrical test), that provides or enhances the (Successful SO package test), under condition of the (Continuity Problem).

  16. Find a way to enhance the (Electrical test).

  17. Find a way to protect the (Electrical test) from the harmful influence of the (Continuity Problem).

  18. Find a way to do without the (Electrical test) for obtaining the (Successful SO package test).

  19. Find a way to eliminate, reduce or prevent the (Continuity Problem), under the condition of the (Contact finger lateral movement) and (Contact pressure varies).

  20. Find an alternative way to obtain the (Testing cycle completed), that does not require the (Successful SO package test).

  21. Find a way to enhance the (Testing cycle completed).

  22. Find a way to eliminate, reduce or prevent the (Contact finger lateral movement), under the condition of the (Plunger pushes part into contactor) and (Contactor fingers push up against part leads).

  23. Find a way to eliminate, reduce or prevent the (Contact pressure varies), under the condition of the (Contactor fingers push up against part leads).

  24. Find a way to eliminate, reduce or prevent the (Chaffed elastomer support pad), under the condition of the (Contact finger lateral movement).

  25. Find a way to eliminate, reduce or prevent the (Exposed fibers entangled with part), under the condition of the (Chaffed elastomer support pad).

  26. Find an alternative way to obtain the (Successful SO package test), that provides or enhances the (Testing cycle completed), and does not require the (Electrical test), (Contact pressure), and (Part falls into shuttle).

  27. Find a way to enhance the (Successful SO package test).

  28. Find a way to do without the (Successful SO package test) for obtaining the (Testing cycle completed).

  29. Find an alternative way to obtain the (Contact pressure), that provides or enhances the (Successful SO package test), and does not require the (Plunger pushes part into contactor) and (Contactor fingers push up against part leads). This way should not be influenced by the (Contact finger lateral movement) and (Contact pressure varies).

  30. Find a way to enhance the (Contact pressure).

  31. Find a way to protect the (Contact pressure) from the harmful influence of the (Contact finger lateral movement) and (Contact pressure varies).

  32. Find a way to do without the (Contact pressure) for obtaining the (Successful SO package test).

  33. Find a way to eliminate, reduce or prevent the (SO package jams), under the condition of the (Exposed fibers entangled with part).

  34. Find an alternative way to obtain the (Plunger retracts), that provides or enhances the (Part falls into shuttle).

  35. Find a way to enhance the (Plunger retracts).

  36. Find a way to do without the (Plunger retracts) for obtaining the (Part falls into shuttle).

  37. Find an alternative way to obtain the (Contactor fingers push up against part leads), that provides or enhances the (Contact pressure), but does not cause the (Contact finger lateral movement) and (Contact pressure varies), and does not require the (Proper positioning of SO package).

  38. Find a way to enhance the (Contactor fingers push up against part leads).

  39. Find a way to resolve the contradiction: the (Contactor fingers push up against part leads) should exist to obtain the (Contact pressure), and should not exist in order to avoid the (Contact finger lateral movement) and (Contact pressure varies).

  40. Find a way to do without the (Contactor fingers push up against part leads) for obtaining the (Contact pressure).

* Basic Directions for Innovation are automatically generated by Problem Formulator and are based on the diagram.


Step 3: Prioritize Directions and Generate Preliminary Ideas

¨ 1. Directions selected for further consideration

19. Find a way to eliminate, reduce or prevent the (Continuity Problem), under the condition of the (Contact finger lateral movement) and (Contact pressure varies).

Consider removing the source of the harmful effect from the system or process.

Exclude that portion of the system or process that is the most sensitive to the harmful action.

22. Find a way to eliminate, reduce or prevent the (Contact finger lateral movement), under the condition of the (Plunger pushes part into contactor) and (Contactor fingers push up against part leads).

23. Find a way to eliminate, reduce or prevent the (Contact pressure varies).

24. Find a way to eliminate, reduce or prevent the (Chaffed elastomer support pad), under the condition of the (Contact finger lateral movement).

25. Find a way to eliminate, reduce or prevent the (Exposed fibers entangled with part), under the condition of the (Chaffed elastomer support pad).

30. Find a way to enhance the (Contact pressure).

31. Find a way to protect the (Contact pressure) from the harmful influence of the (Contact finger lateral movement) and (Contact pressure varies).

33. Find a way to eliminate, reduce or prevent the (SO package jams), under the condition of the (Exposed fibers entangled with part).

¨ 2. Refined Directions for Innovation

  1. Change the undesired action of the (Continuity Problem).

  2. Consider easy and timely detection of the action of the (Continuity Problem) or its undesired results.

  3. Provide a counteraction to the undesired action of the (Continuity Problem).

  4. Introduce isolation of the undesired action of the (Continuity Problem).

  5. Exclude the source of the undesired action of the (Continuity Problem).

  6. Employ negative feedback to control the undesired action of the (Continuity Problem).

  7. Consider localizing the undesired action of the (Continuity Problem) to prevent its harmful results.

  8. Immediately compensate for the consequences of the undesired action of the (Continuity Problem).

  9. Try to eliminate or reduce the causes of the undesired action of the (Continuity Problem).

  10. 'Blend in' the defects produced by undesired action of the (Continuity Problem).

  11. Remove a sensitive part of the system to reduce the influence of the undesired action of the (Continuity Problem).

  12. Consider transient use of substances to reduce the influence of the undesired action of the (Continuity Problem).

  13. Reduce the sensitivity of the entire system to the undesired action of the (Continuity Problem).

  14. Provide isolation of the object [of] the (Continuity Problem) to avoid harm.

  15. Utilize a model of the object [of] the (Continuity Problem) to avoid harm.

  16. Consider removing the object [of] the (Continuity Problem) from the system to avoid harm.

  17. Modify the undesired characteristic [of] the (Continuity Problem) in the desired way.

  18. Improve a prototype to provide the action of the (Contactor fingers push up against part leads) in an alternative way.

  19. Increase the level of ideality of the object [of] the (Contactor fingers push up against part leads).

  20. Simplify the object [of] the (Contactor fingers push up against part leads).

  21. Keep or enable those parts of the object [of] the (Contactor fingers push up against part leads) that provide the (Contact pressure), and remove or disable those parts that cause the (Contact finger lateral movement) and (Contact pressure varies).

¨ 3. List and categorize all preliminary ideas

  • Increase surface area of leads past spring area to allow greater mechanical holding strength.

  • Leads should be wide but should not touch. Secondary Problems: if they are too wide the part can go between two and short out the leads; also, lateral movement would short out fingers.

---------------

  • Kelvin leads should have the same mechanical force as other leads (same moment arm). Keep part in stable orientation.

  • Secondary Problems: adjustment and placement

--------------

  • Bumps under the tape that prevents the lateral movement

  • Secondary Problems: friction between divider and contact spring may limit spring elasticity

  • Possible cure would be to move the divider out of the major deformation area. Separation in space – divider is not in the area where the spring is moving – it is in the area to prevent lateral movement

  • Secondary Problems: could limit movement

------------------

  • Use shape of the contact (as a pocket) so that the lead of the SO self-centers each time

  • Secondary Problems: leads may have to be wider

--------------------

  • Use air to free a stuck part

-------------------

  • Use fake Kelvin contacts to balance forces

--------------------

  • Make one-piece Kelvin contacts

  • Secondary Problems: don't have contact edge and would have different spring force

------------------

  • Having glue on the non-elastic part to hold in place

  • Secondary Problems: overall elasticity would drop

-------------------

  • Use PC board to replace the elastomer Secondary Problems:; the elastomer is used as a part of the spring action

------------------

  • Find a way to redirect the moment arm force

------------------

  • Replace the spring with a probe or pogos

  • Secondary Problems: vertical distance is a problem (mechanically and electrically) for lead inductance

------------------

  • Stiffen the contacts and put a material with conductive polymer bumps over contacts

  • Secondary Problems: none

------------------

  • Use elastomer spheres (could be on top of Kelvin contact) – all forces are identical

  • Secondary Problems: problem with Kelvins

  • Use split sphere with insulator in between

-----------------

  • Put a spring under or on top of the plunger plate (use a dot of RTV on top); natural motion would be to push plunger away.

--------------

  • Slow down the plunger

  • Secondary Problems: would have to change the timing of the plunger

---------------

  • Spring on the bottom of the plunger so that it doesn't hit as hard

  • Secondary Problems: can slow down the plunger too much

------------------

  • Make plunger out of elastic material

  • Secondary Problems: potential resistivity issues; permanent deformation of the plunger

-------------------

  • Place counterweight on relays

  • Secondary Problems: complexity

------------------

  • Liquid contacts, low resistivity

  • Secondary Problems:: Initial cost may be high


Step 4: Develop Concepts

¨ 1. Combine ideas into Concepts

  • Combination of PC board and redirection of moment arm force. This will eliminate the harmful effects associated with the arm by replacing the arm with the little spheres, providing a redirection of force (like a spring action).

  • Combination of RTV (dot of elastic polymer) with PC board

¨ 2. Apply Lines of Evolution to further improve Concepts

Increasing dynamicity and controllability support the transition from fingers to flexible (elastomer) balls

Increasing complexity then simplification supports the use of a split elastomer ball with an insulator to meet the Kelvin requirements

¨ 3. Obtain resources to accomplish Concepts

No additional resources required


Step 5: Evaluate Results

¨ 1. Meet criteria for evaluating Concepts

None

¨ 2. Reveal and prevent potential failures

Split ball could present new problems

Mechanical cycling of elastomer ball

¨ 3. Plan the implementation

Development work needs to be defined.

There is a need to consult with experts on the utilization of split elastomer balls

(END OF CASE STUDY)


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