Custom Heatsink Development

At Celsia, we have honed a streamlined process for developing custom heatsinks, ensuring optimal thermal performance and timely delivery. Below is an overview of our process, including typical turnaround times for each step.

Step 1: Define Heatsink Requirements

Timeframe: A few days to a week depending on the customer’s schedule.

The first step in designing an effective custom heat sink is collecting application-specific data. If some values are unknown, estimates are acceptable. We frequently schedule video calls to clarify design intent and address technical challenges early. Here are some of the information we collect:

1. Application Type
   • Examples: military land electronics, telecom infrastructure equipment, low-orbit satellites.
2. Heat Source (for each IC that needs to be cooled)
   • Power in watts (TDP).
   • Size (LxW).
   • Lidded or unlidded IC.
   • Max Tcase or Tjunction in °C.
   • Duty cycle (if applicable).
3. Operating Environment
   • Min/Max operating temperature (°C).
   • Min/Max storage temperature (°C).
   • Elevation range (above/below sea level).
   • Other environmental factors: high shock and vibe environments, heat, humidity, salt spray, etc.
4. Custom Heatsink Specifications
   • Natural or forced convection.
   • Airflow into heatsink (CFM or Velocity).
   • Available space for the heatsink (LxWxD).
   • Distance of heatsink relative to heat source (local or remote condenser).
   • Angle of orientation range (heat source location relative to condenser).
   • Rank order importance of size, weight, performance/power, and cost (SWaP-C).
   • If possible, provide STEP or other CAD files.

Step 2: Initial Custom Heatsink Thermal Modeling

Timeframe: A few days to a week per iteration; expect 2-4 iterations.

Celsia uses internal thermal simulation tools to model and compare multiple custom heat sink concepts. These models help us spot thermal bottlenecks and refine performance targets early in the design cycle.

1. Video Conference
   • Discuss results and assess feasibility.
   • Adjust SWAP-C priorities given known constraints.
2. Iterative Refinement
   • Re-run thermal models, generate reports, and refine the custom heatsink design through ongoing customer collaboration.

Step 3: CFD Development & Optimization

Timeframe: 1-2 weeks per iteration (minor tweaks faster). This step typically lasts 1-4 months, depending on the number of CFD iterations and customer response time to suggested changes.

As a manufacturer of custom heat sinks, we offer flexible CFD support based on your internal capabilities:

1. Fully Turnkey: Celsia performs all CFD analysis, including fin geometry, air velocity, and surface temperatures.
2. Partial Support: We provide thermal design guidelines—such as material conductivity, fin dimensions, and pressure drop assumptions—for customer-executed simulations.
3. Scope and Pricing: CFD work focuses on the custom heat sink (not the full enclosure) unless requested. Budgetary pricing is based on file quality and simulation complexity.

Step 4: Finalize Custom Heatsink Design for Prototype Build

Timeframe: 1-2 weeks if based on optimized STEP/CFD files.

While further refinement is likely after prototype testing, this step should include drawings, specifications, and tolerances. Like the CFD stage, this heatsink design stage can be turnkey or involve limited Celsia participation.

Step 5: Prototype – Tooling, Production, & Validation

This step involves soft tooling, production and testing jigs, prototype build, and Celsia testing of the thermal solution before being shipped to the customer.

Timeframe: 6-8 weeks, depending on the design.

Testing includes:

1. Thermal Evaluation: Thermal resistance and delta-T tests at room ambient are standard. If needed, we also conduct tests under customer-specified low- or high-ambient conditions.
2. Mechanical Testing: Includes dimensional inspection and optional shock/vibration testing based on industry or customer standards.

Step 6: Customer Prototype Testing, Design Refinements

Timeframe: Duration is entirely dependent on the customer’s schedule.

Customers install the custom heat sink prototype into their system for operational testing. Feedback from this stage is used to finalize the design.

Step 7: Custom Heatsink Mass Production

Timeframe: 6-10 weeks, depending on the complexity and order volume.

Celsia’s mass production capabilities include hard tooling, fixture development, and rigorous testing. Whether producing thousands of units or low-volume specialty designs, custom heat sinks are manufactured with precision and repeatability.

1. First Article Testing: As outlined in the “Quality System Overview” document.
2. Mass Production QC Testing: Every custom heat sink or thermal assembly undergoes thermal, mechanical, and cosmetic inspection. All two-phase components receive 100% functional testing unless otherwise specified.

Total Lead Time Guidance for Custom Heatsinks

Celsia’s lead time for a complete custom heatsink development cycle is roughly 5 to 8 months. However, built-to-print thermal assembly projects can be done in half the time.

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