How to Specify a Custom Liquid Cold Plate: Complete RFQ Checklist

How to Specify a Custom Liquid Cold Plate: Complete RFQ Checklist

Getting a custom liquid cold plate right — on time, on budget, and to specification — depends almost entirely on the quality of your RFQ (Request for Quotation). Incomplete or ambiguous specifications lead to costly design iterations, failed prototypes, and delayed programs. This guide provides a complete, field-tested RFQ checklist developed from thousands of custom cold plate projects.

1. Thermal Requirements

Thermal requirements are the foundation of any cold plate specification. Missing or incorrect thermal data is the single most common cause of failed cold plate designs.

Required thermal parameters for your RFQ:

• Maximum heat load (W): Peak power dissipation of the component(s) to be cooled. State both continuous and transient (peak) values.
• Heat source footprint (mm × mm): Active area dimensions of each heat source (die, module, cell).
• Inlet coolant temperature (°C): Specify worst-case inlet temperature from the CDU or chiller.
• Maximum allowable component temperature (°C): Usually Tj_max or TCASE_max from the component datasheet.
• Target thermal resistance (°C/W): If known — or allow the manufacturer to calculate from the above parameters.
• Coolant flow rate (L/min) and pressure drop budget (kPa): Constrained by your pump curve.
• Coolant type: DI water, 50/50 EGW (ethylene glycol/water), propylene glycol, or other. This affects material compatibility.

2. Mechanical Dimensions

Mechanical specifications define the physical envelope and interface requirements of the cold plate. Provide a detailed 2D drawing (DXF, DWG) or 3D model (STEP, IGES) wherever possible.

• Overall envelope (L × W × H mm): Maximum allowable dimensions including manifold and port protrusion.
• Mounting hole pattern: Location, diameter, thread specification, and flatness tolerance of mounting surface.
• Flatness requirement (mm): Surface flatness at the contact interface — critical for GPU and IGBT thermal contact. Specify tolerance (e.g., ≤0.05 mm over the contact area).
• Surface roughness (Ra μm): Required surface finish at the component interface. Typically Ra ≤ 0.8 μm for GPU direct contact.
• Inlet/outlet port size and location: G1/4″, NPT1/4″, or custom. Specify entry angle (top, side) and exact position.
• Weight budget (g): If weight-constrained (e.g., airborne or vehicle-mounted).
• Environmental protection: IP rating or conformal coating requirements if applicable.

3. Material Selection Guide

Material selection significantly impacts thermal performance, weight, corrosion resistance, cost, and compatibility with your coolant. Use this table to guide your decision:

4. Manufacturing Process Options

The manufacturing process determines the internal channel geometry, thermal performance, pressure rating, and thermal cycling durability of your cold plate:

• Vacuum Brazing (copper/aluminum): Bonds fin arrays and cover plates in a vacuum furnace. Produces void-free joints with excellent thermal contact. Standard for high-performance copper cold plates and AI server cooling.
• Friction Stir Welding (FSW): Solid-state welding process for aluminum. Produces high-integrity joints without melting the base material — critical for EV battery cold plates and automotive qualification.
• Controlled Atmosphere Brazing (CAB): High-volume aluminum brazing in nitrogen atmosphere. Used for automotive and HVAC heat exchangers. Lower tooling cost for large production volumes.
• CNC Machining + Diffusion Bonding: For complex geometries or research prototypes. Higher cost per unit but maximum design flexibility.

5. Quality & Compliance Requirements

State all quality and regulatory requirements upfront. Discovering these late adds cost and delays:

• Quality management system: ISO 9001:2015 (ToneCooling is ISO 9001 certified)
• RoHS / REACH compliance: Required for EU and most US end-markets
• Pressure test requirement: Specify hydrostatic test pressure (e.g., 2× MAWP) and leak test method
• PPAP documentation level: For automotive OEM programs (Level 1–5). ToneCooling provides PPAP Level 3.
• First Article Inspection (FAI): Dimensional report to drawing with actual measurements
• Material certifications: Mill test reports for base material traceability
• Thermal performance test report: Specify test conditions (flow rate, inlet temp, power input) and required pass criteria (Rth or ΔT)

6. Volume & Timeline

Providing clear volume and timeline information allows manufacturers to optimize tooling investment and production planning:

• Prototype quantity: Typically 5–20 pieces for design validation (ToneCooling MOQ: 5 pieces)
• Pilot/pre-production quantity: 50–200 pieces for design freeze and qualification testing
• Annual production volume: Drives tooling amortization and per-unit pricing decisions
• Required prototype date (NTE date): Hard date for design validation testing or program milestone
• Production ramp start date: When production volume needs to begin shipping
• Delivery location: Country/region — affects logistics planning and export documentation (e.g., USA delivery or Europe delivery)

7. Common RFQ Mistakes to Avoid

References & Further Reading

• Electronics Cooling Magazine — Thermal Management Technical Resources
• Semiconductor Engineering — Thermal Management Knowledge Center

Custom Liquid Cold Plate RFQ: Essential Parameters

A well-prepared custom liquid cold plate RFQ dramatically reduces engineering review cycles. Based on ToneCooling’s analysis of 850+ RFQs in 2025, submissions that include all 12 parameters receive quotes within 24-48 hours, compared to 11+ days for incomplete requests.

Your custom liquid cold plate RFQ should always specify the heat source footprint, total thermal dissipation (TDP), maximum junction temperature, coolant type and inlet temperature, and acceptable pressure drop. These five parameters alone eliminate 80% of clarification rounds.

Ready to submit your custom liquid cold plate RFQ? Contact ToneCooling engineering team — prototype lead time is 7-15 business days.

Frequently Asked Questions