How to Prepare an RFQ for a Custom Cold Plate: A Complete Checklist

Custom cold plate RFQs often don’t get a quote on the first pass. More often, the reply that comes back isn’t a price. It’s a list of questions. What’s the contact area of each heat source? What’s the coolant inlet temperature? How much pressure drop can the loop afford? Do you need helium leak testing? Every round of back-and-forth pushes the project back a little further.

The problem usually isn’t the supplier. It’s the RFQ. A cold plate RFQ (request for quotation) is the package of drawings, thermal targets, coolant data, test requirements, and volumes a buyer sends so a manufacturer can evaluate and price a custom cold plate. It isn’t a “please quote” email. It’s the first engineering document of the entire project. The factory uses it to decide whether the part can be built, which structure and process to use, what to test, and where the cost will land. The more complete the information, the more accurate the quote, and the fewer rounds of rework you’ll face at the sample stage.

This guide is a custom cold plate RFQ checklist for procurement and engineering teams. It covers which specifications to include, why each item matters, and what to do when you don’t have all the data yet.

What Should a Custom Cold Plate RFQ Include?

A complete custom cold plate RFQ includes:

1. 3D model and toleranced 2D drawing
2. Power, location, and contact area of each heat source
3. Maximum temperature or target thermal resistance, with test conditions
4. Coolant type and inlet temperature
5. Flow rate and pressure drop budget
6. Operating pressure and leak test requirements
7. Prototype quantity, annual volume, and timeline

Why Cold Plate RFQ Completeness Decides Quote Accuracy

An incomplete RFQ forces the manufacturer to guess, and a wrong guess can lead to a requote or a failed prototype.

When a factory receives an RFQ, the first step is an engineering review. The team checks whether the requirements are physically achievable, picks a channel structure and joining process, defines the test scope, and then works out material, machining, and inspection costs. Each step depends on the one before it. When an input is missing, the engineer has to fill the gap with an assumption.

Assumptions aren’t the problem. The problem is when they don’t match your actual operating conditions. Say you leave out the coolant, so the factory assumes water. But your system actually runs PG25, which is more viscous than water and has a lower specific heat. At the same flow rate, both the temperature rise and the pressure drop will change, and the performance margin you were counting on may disappear. You still get a quote, but it rests on the wrong premise. The mismatch often surfaces at the prototype stage, which means a redesign and a new quote.

A complete RFQ saves more than a few emails. It saves you from building a prototype in the wrong direction. To see how engineers turn these inputs into an actual cold plate structure, read our cold plate design guide.

The Custom Cold Plate RFQ Checklist

Use the table below as a quick reference. “Required” means the factory can’t quote without it. “Recommended upfront” means a quote is still possible without it, but price and lead time may change later. “Can follow later” means it can be settled during the engineering review.

The sections below cover the details that are most often missed or misstated.

Mechanical Interface

• 3D model plus 2D drawing. A neutral format such as STEP is the safest choice for the 3D model. The 2D drawing should call out datums, critical tolerances, and flatness and roughness requirements for the contact surface.
• Envelope and keep-out zones. The maximum space the cold plate, fittings, and tubing can occupy, especially the height limit.
• Mounting method. Hole locations, clip or screw specifications, and any assembly sequence requirements.
• Port location and orientation. Port direction dictates how the internal channels can be routed.

One point often gets overlooked: the more hole and port locations are locked in place, the more the channels have to route around them. That adds design complexity and cost. If some of those positions can actually move, mark them as “adjustable” in your RFQ. It gives the engineer more room to optimize.

Thermal Requirements

• Power, location, and contact area of each heat source. Total power alone isn’t enough. A 1,000 W load on a single chip and 1,000 W spread across six devices call for completely different designs. List maximum sustained power, not just typical power.
• Heat map. If the chip has distinct hotspots, a heat map lets the engineer target the channel layout where it matters.
• Maximum allowable temperature. This is usually the chip case temperature, the cold plate surface temperature, or, for batteries, the cell temperature. State which one you mean.
• Temperature uniformity. For battery modules, lasers, and similar applications, the temperature spread often matters more than the peak temperature.

The first step in custom cold plate design is to use this data to define the thermal map. A complete thermal section leads directly to a more accurate channel design.

Coolant, Flow Rate, and Pressure Drop Budget

• Coolant type and concentration. DI water, PG25, ethylene glycol-water, or another fluid. Include the concentration and the specific brand and product. The coolant drives both heat transfer performance and material compatibility. PG25, widely used in data centers, must contain an inhibitor package matched to the metals in the loop. So even if two systems both run PG25, the exact formulation still needs to be stated.
• Inlet temperature range. List the maximum, not just the typical value. The warmer the coolant coming in, the harder the cold plate has to work.
• Available flow rate. How much flow each cold plate will actually receive. If you’re not sure yet, estimate it from the heat load. In AI server cold plate loops, for example, a common design target with PG25 is about 1.5 LPM/kW, which corresponds to a coolant temperature rise of about 10°C.
• Pressure drop budget. The maximum pressure drop allowed across the cold plate, fittings included, at that flow rate. It depends on the pump or CDU head and how much of it the rest of the loop already uses.

Pressure, Leak, and Reliability Requirements

• Maximum operating pressure.
• Proof pressure. For data center cold plates, one reference point is the IEC 62368-1 approach of holding the part at three times its maximum operating pressure and checking for leaks.
• Leak test method and acceptance criteria. Pressure decay, bubble testing, or helium leak detection, and the allowable leak rate.
• Cleanliness. Maximum particle size and residue requirements.
• Reliability testing. Which tests are needed, such as temperature cycling, shock and vibration, or salt spray, and who will run them.

At APALTEK, test items are defined by each customer’s requirements. There’s no fixed checklist applied to every project. Specific requirements here make the inspection cost and lead time in your quote far more accurate. If you don’t have defined test requirements yet, you can simply write “supplier to recommend a test plan.”

Material, Finish, and Joining Preferences

• If you have a preference, state it. Copper or aluminum, nickel plating or not, brazing or friction stir welding. For a comparison of these processes, see our article on the cold plate manufacturing process.
• If you don’t, write “open to supplier recommendation” and note the constraint behind it: weight, cost, or performance.
• List the other wetted materials in the loop. What are the tubing, fittings, manifold, and heat exchanger made of? Mixing copper and aluminum introduces galvanic corrosion risk, so the factory needs the full material picture to assess compatibility.

Commercial Information

• Prototype quantity, pilot quantity, and estimated annual volume
• Project stage and timeline: concept validation, design validation, or production readiness
• Packaging, labeling, and traceability requirements
• Required certifications or compliance documents
• Confidentiality requirements, such as whether an NDA must be signed before drawings are shared

Annual volume shapes the process route. A few dozen samples and tens of thousands of units a year call for very different manufacturing methods and tooling investments. Without an annual volume, the factory can only quote the prototype process, and production pricing may not line up later.

How to Specify Performance Targets So Cold Plate Quotes Are Comparable

To make cold plate quotes comparable, state every performance target together with its test conditions: the thermal resistance definition, heat load and heated area, coolant conditions, interface conditions, and the worst-case operating point.

Thermal resistance is the most misunderstood number in a cold plate RFQ. It describes how much hotter the chip or cold plate surface runs than the coolant for each watt of heat, expressed in °C/W. But suppliers don’t all define it the same way. Some use chip case temperature minus inlet temperature. Others use cold plate surface temperature minus local fluid temperature. Add differences in test coolant, flow rate, heater size, and TIM, and the thermal resistance figures from different suppliers often don’t share a common baseline. You can’t compare them directly.

Spell out these conditions in the RFQ itself:

• Definition: case-to-inlet, or surface-to-local-fluid
• Heat load and heated area: real silicon or a thermal test vehicle (TTV), and the size of the heated area
• Coolant: type, concentration, inlet temperature, and flow rate
• Interface conditions: TIM type and mounting pressure
• Qualification condition: ideally the worst case, meaning the lowest flow rate combined with the highest inlet temperature

A more direct approach is to skip thermal resistance and specify the end result instead, for example: “Under the conditions above, chip case temperature must not exceed XX°C.” That removes any argument over definitions and ties the requirement to the outcome you actually care about.

Application-Specific RFQ Additions

The checklist above applies to every custom cold plate. Each application also has its own critical parameters to add.

Data Center CPU and GPU Cold Plates

• Processor platform. The socket, or the accelerator module form factor such as OAM or SXM. Attach the chip vendor’s thermal and mechanical specifications.
• Mounting pressure, flatness, and TIM. These directly affect contact resistance. For OAM accelerator modules, for example, recommended reference values are cold plate flatness under 0.1 mm and mounting pressure above 40 psi. If the chip vendor specifies requirements for your platform, those take precedence.
• Quick disconnects and manifold interface. The quick disconnect model, the manifold connection type, and whether multiple cold plates run in series or parallel.
• Coverage. Whether the cold plate also needs to cool memory, VRMs, or other nearby components.

If you’re still comparing direct-to-chip cold plate options, start with our guide on how to select the right cold plate for AI applications, then prepare the RFQ once the direction is set.

EV and Energy Storage Battery Cold Plates

• Module or pack layout. Cell arrangement and the contact surface between cold plate and cells.
• Cell-to-cell temperature target. Especially under fast-charging conditions.
• Coolant and operating pressure. Usually ethylene glycol-water. State the concentration.
• Electrical insulation and thermal interface requirements.
• Shock and vibration. Name the standard, such as SAE J2380, a recommended practice for battery vibration durability testing, or the OEM’s own road load profile.
• Weight limits.

Power Electronics, Laser, and Medical Equipment

• Power modules such as IGBTs: device layout, power per device, and maximum junction temperature.
• Lasers: temperature control accuracy and stability, which often matter more than maximum heat dissipation.
• Medical equipment: cleanliness requirements and material restrictions.

What If You Don’t Have All the Data Yet?

You can still send a cold plate RFQ with incomplete data: use ranges, mark which values are estimates, and ask for a feasibility review first. Many projects are still early when they go out for quote. Chip power isn’t final, and the chassis design is still changing. Here’s how to handle it.

• Use ranges instead of blanks. “600–800 W” or “1–2 LPM” is far more useful than an empty field. The engineer can design to the upper end of the range and tell you which parameter is the bottleneck.
• Mark which values are firm and which are estimates. That tells the factory where to build in margin.
• Ask for a feasibility review before a formal quote. Send what you have, confirm the design direction and key risks first, and request a formal quote once the data is settled.

For projects still being defined, this kind of co-development is usually more efficient than revising the RFQ over and over.

Common Cold Plate RFQ Mistakes That Delay Quotes

• Sending only an STL file. STL captures shape but not tolerances or datums. The factory can’t tell what the sealing and contact surfaces require, so another round of questions follows.
• Giving power but not contact area. Without it, the engineer can’t calculate heat flux or judge how aggressive the channel structure needs to be.
• Writing “as low as possible” for pressure drop. Performance and pressure drop are a trade-off. With no upper limit, the engineer has to design conservatively, which can mean a larger, more expensive part.
• Leaving out annual volume. The quote can only reflect the prototype process, and both price and process may need to be revisited for production.
• Skipping test requirements. The quote may cover only a basic leak test. Adding tests later changes both price and lead time.
• Sending drawings without revision numbers. During design iterations, the factory may quote an outdated version, and nobody notices until the samples arrive.

FAQ

What is the minimum information needed for a cold plate quote? At a minimum, a supplier needs six things: the envelope or drawing, the power and contact area of each heat source, and the maximum allowable temperature. It also needs the coolant type and inlet temperature, the available flow rate and pressure drop budget, and the prototype quantity and annual volume. Other parameters can be added during the engineering review.

Should I include a target price in a cold plate RFQ? You can, but it isn’t required. A target price helps the factory decide how to balance performance and cost, for example whether a more economical structure or process could still meet your requirements. Without one, the factory will typically quote the design that meets your technical specs.

Do I need a thermal simulation before sending a cold plate RFQ? No. Channel design and performance evaluation are the supplier’s job. As the buyer, you only need to provide accurate boundary conditions. If you already have system-level simulation results, including them can help the factory confirm the design faster.

Can the manufacturer recommend the material and process for me? Yes, as long as the manufacturer works with more than one process. A shop that runs only one process will usually recommend the one it knows. For a practical way to evaluate suppliers on this point, see our roundup of liquid cold plate manufacturers in China.

Get Your First Quote Closer to the Final Answer

A good cold plate RFQ puts the constraints you already know into a form an engineer can use right away. The more complete the data and the clearer the conditions, the more accurate the quote, and the better your chances of getting the prototype right the first time.

APALTEK’s engineering team supports the full process, from design evaluation and prototyping to testing and volume production. Send us your drawings and the parameters from this checklist. Even if your data isn’t complete yet, our engineers can start with a design evaluation based on what you have.

Submit your cold plate project for an engineering review.