Alice W. Leung

Soldering Components

Coil-tip Soldering Fixture

Engineering, Ergonomics, Efficiency, Usability Evaluation, 3D Prototyping, Contextual Inquiry

Researcher/Creator: A. Leung

Project Overview

Disclaimer: Certain content of products, tools, or process are proprietary information, and therefore not shown on this page. Most content and terms in this project are generalized to protect company rights.


As part of catheter assembly, a metal tip is bonded to a long length metal coil by a soldering process, which is heating a low-melting alloy to fuse the two components together.

People with a pair of hands can only hold two objects at once. In this case, there are 3 objects that required holding:

  • Soldering Iron
  • Long Length Metal Coil
  • Metal Tip

Operators instinctively put together a fixture to hold the metal tip while their hands are busy holding the soldering iron and the metal coil. However, this fixture was made with three layers of razor blades stacked on top of each other, taped onto their workbench.

Ergonomic / Safety

Even though razor blades are taped together and on top of a work bench, these objects are sharp and as the tape is worn down due to use, sharp edge may be exposed and therefore becoming a hazardous object for people to use.

Low Efficiency & One-Time Use

Three layers of razor blades are disposed every shift or process at every station. More razor blades are used due to this need of holding a third object.

Contextual Inquiry

Contextual Inquiry

Understand what we currently have
  • How the 3-layer razor blades were put together.
  • How they hold the objects during soldering process.
  • How the razor blades and tape get worn out/corroded due to flux usage.
  • When they discard razor blades at the end of each shift/process.

Quotes from operators:

  • We always have to spend time on setting this fixture up at the beginning of this soldering process…
  • These things get rusted all the time…
  • I cut myself a couple times while using this…

User Requirements

User Requirements

Insights from observation and interview findings
  • Need to be safe and not sharp to prevent injury during process.
  • Need to prevent hand/arm fatigue during use.
Material Selection
  • Need material that will withstand as high as a soldering temperature of 650°F.
  • Need material that will not corrode when using flux, and can be cleaned easily.
  • Need material that will not move easily on the workbench without using tape.
  • Consider the different techniques operators used to hold the coil and tip.
  • Consider the height of fixture due to use of microscope during soldering process.

Conceptual Design

Conceptual Design

Learning from operators

We leveraged the 3-layer razor blades concept already ideated by the operators, to design a better, safer, and long-lasting solution.

3D Prototyping

3D Prototyping

1st Prototype
  • Material: ABS (Delrin)
  • Prototyping Method: 3D Printing
  • Design: 1-inch block with semi-circle cutouts on 4 sides.
  • Usability Testing Results:
    • Too thick for operators to use and look under the microscope.
    • Semi-circle cutouts too deep.
    • Cannot see the components during soldering because of the depth of semi-circle cutouts.
2nd Prototype
  • Material: ABS (Delrin)
  • Prototyping Method: 3D Printing
  • Design:
    • Thin rectangular sheet
    • Semi-circle cutouts on 4 sides.
    • Added a triangular opening to cutouts
  • Usability Testing Results:
    • Too flat for people to hold metal tip against metal coil.
    • Semi-circle is too smooth, can misalign during soldering.
    • No place to rest metal coil when soldering with one technique.
3rd Prototype
  • Material: PEEK Material
  • Prototyping Method: Machined
  • Design:
    • Flat rectangular plate
    • Triangular opening + semi-circle cutouts on 4 sides.
    • Added a groove in the center parallel to the long side of the plate.
  • Usability Testing Results:
    • The fixture works as intended, but it still moves on the workbench during soldering.
Final Prototype
  • Material: PEEK Material + Silicone
  • Prototyping Method: Machined + Hand-cut
  • Design:
    • Flat rectangular plate.
    • Triangular opening + semi-circle cutouts on 4 sides.
    • Groove in the center parallel to the long side of plate.
    • Added a thin sheet of silicone pad on the bottom of plate for gripping purposes.
  • Usability Testing Results:
    • Fixture is safe and works for the intended soldering purposes.
    • Operators can fix components during soldering and look into the microscope with no trouble.
    • Fixture does not move on the workbench during soldering and does not require tape.
    • PEEK material does not corrode and can withstand high soldering temperature.
    • Cleaning steps are easy to remove flux.
    • People can re-use this fixture for each shift/process for 6+ months.
    • Fixture can be used either on the short side or the long side depending on people’s technique preferences.


Establish Specification

Document all ideas and testing

Dimensional and material requirements are specified in official drawings for documentation purposes and future production needs.

Business Impact

Business Impact

Cost Savings

The cost savings associated with this project was estimated to be $25,000 per year.

Ergonomic/Psychological Impact

Operators are happy because they can save time and re-use this fixture for soldering components every shift. Razor blades are no longer used as a fixture for this process.

Recent Works