This page is dedicated to the performance, manufacturing, and testing of custom-made heat pipes. If you are looking for custom heat-pipe heat sinks (also known as heat-pipe assemblies or heat-pipe modules), please visit this page.

Custom heat pipes are initially manufactured as round pipes but can be tailored to specific needs through bending, flattening, and other modifications to achieve the desired 2D or 3D shapes. These heat pipes can efficiently transfer heat from the source to virtually any location required by your application.

Customization options include, but are not limited to:

Custom Length: Available in increments of 1 mm, ranging from 80 mm to 600 mm.
Wall Thickness: Adjustable to suit specific applications or secondary machining needs.
Bending: Forming 2D or 3D Shapes, adhering to minimum bending radii.
Flattening: Fully or partially flattened to meet space and flatness requirements.
Fluid and Vacuum Optimization: Tailored fluid amount and vacuum pressure for operational conditions.
Performance Testing: Verified under actual orientation and application scenarios.
Rapid Prototyping: Standard turnaround of 5-10 days, with expedited options available.
Surface Finishes: Anti-oxidation treatment or electroless nickel plating

Bending of Heat Pipes

To minimize the impact on thermal performance, we recommend the following bending radii and angles as the design guidelines.

Diameter	Minimum R	Suggested R	Minimum Bending Angle	Suggested Bending Angle
4 mm	9 mm	12 mm	90 °	120 °
5 mm	12 mm	15 mm	90 °	120 °
6 mm	14 mm	18 mm	90 °	120 °
8 mm	20 mm	24 mm	90 °	120 °

To make sure custom bent heat pipes are manufacturable, the inner radius needs to be at least 2x the diameter of the heat pipe. Otherwise, the heat pipe will be internally damaged during bending.The Qmax will reduce by about 2.5% for every 45-degree bend. The performance of the heat pipe will decrease by about 20% after the first bend, and then down by 10% for each additional bend.

Flattening of Heat Pipes

The following table provides a guideline for the flattening of heat pipes. For diameters and thicknesses not listed in this table, please contact us.

Diameter (D)	Thickness (T)	(T) Tolerance	Width (W)	(W) Tolerance
Ø4	2.0	+0.05/-0.10	5.23	+/-0.15
Ø4	2.5	+0.05/-0.10	4.96	+/-0.15
Ø4	3.0	+0.05/-0.10	4.65	+/-0.15
Ø5	2.0	+0.05/-0.10	6.82	+/-0.15
Ø5	2.5	+0.05/-0.10	6.53	+/-0.15
Ø5	3.0	+0.05/-0.10	6.26	+/-0.15
Ø5	3.5	+0.05/-0.10	5.95	+/-0.15
Ø5	4.0	+0.05/-0.10	5.63	+/-0.15
Ø6	2.0	+0.05/-0.10	8.45	+/-0.15
Ø6	2.5	+0.05/-0.10	8.16	+/-0.15
Ø6	3.0	+0.05/-0.10	7.84	+/-0.15
Ø6	3.5	+0.05/-0.10	7.57	+/-0.15
Ø6	4.0	+0.05/-0.10	7.30	+/-0.15
Ø8	2.0	+0.05/-0.10	11.65	+/-0.15
Ø8	2.5	+0.05/-0.10	11.39	+/-0.15
Ø8	3.0	+0.05/-0.10	11.15	+/-0.15
Ø8	3.5	+0.05/-0.10	10.83	+/-0.15
Ø8	4.0	+0.05/-0.10	10.60	+/-0.15
Ø8	4.5	+0.05/-0.10	10.27	+/-0.15
Ø8	5.0	+0.05/-0.10	10.01	+/-0.15
Ø8	6.0	+0.05/-0.10	9.36	+/-0.15

To Estimate Width

W = Width of Heat Pipe

D = Diameter of Heat Pipe

T = Thickness of Heat Pipe (when flattened)

After flattening, heat pipes cannot be bent out-of-plane (no exceptions). Heat pipes can only be bent out-of-plane when the heat pipe is round.

Super Thin Heat Pipes for Smart Phones and Mobile Devices

We make heat pipes that are as thin as 1.0 mm (0.040″), which can be used on smartphones, laptop computers, tablets, and other miniature electronic devices. The heat pipes are 100% individually tested to ensure heat transfer efficiency. Other thicknesses, including 1.2 mm, 1.5 mm, 1.6 mm, and 1.8 mm, are also available.

Testing of Custom Heat Pipes

Effective Thermal Conductivity

With the heat absorbed by the heat pipe (Q), the thermal resistance (R) and equivalent thermal conductivity (K) of the heat pipe can be calculated.

Q: Heat flux

Standard Testing Setup

A: Sectional Area of test object

ΔX: Distance from the heating end to the condensation end

ΔT: Difference between the reference temperature of the heating end and the reference temperature of the condensation end

Heat Transfer Capacity (Q_max)

Heat Transfer Capability

Heat Pipe Shape	Cross-sectional Dimensions (mm)	Length (mm)	Minimum Bending Radius (mm)	Heat Transfer Rate (L=150mm) (W)
Round Pipe	Ø4	60-600	10	30
Round Pipe	Ø5	60-600	10	45
Round Pipe	Ø6	60-600	12	72
Round Pipe	Ø8	60-600	24	120
Flattened Pipe	Ø4 X 2.0T	60-600	10	25
Flattened Pipe	Ø5 X 2.0T	60-600	10	31
Flattened Pipe	Ø6 X 2.0T	60-600	12	42
Flattened Pipe	Ø8 X 2.0T	60-600	25	55

Step 1:

Place the test object between the heating end and the condensation end.

Step 2:

Input heat from a controllable heat source and remove the heat from the water cooling through the specimen.

Step 3:

Measure the heating end, the reference temperature of the condensing end and the temperature of other points (Tc1, Tc2, Thc, Thb) on the heat pipe.

Reliability Test

No.	Test Item	Typical Test Conditions	Sampling Ratio	Purpose
1	High Temperature Aging Test	Ambient temperature of 210°C for 12 hours	100%	Check for leakage and aging
2	Thermal Response Test	Insert 1/3 to 1/2 length of pipe into 65°C water. The opposite end should reach the standard temperature in 25 seconds	100%	Verify vacuum integrity and check for leakage
3	Qmax Test	Heating length: 25-35 mm, Test temperture: 60°C	100%	Measure maximum heat transfer rate
4	Thermal Resistance Test	Fix heat transfer rate and measure temperature difference along the heat pipe	1 sample per 2 hours	Ensure thermal resistance is within specifications
5	Accelerated Life Test	140°C for 1000 hours, with performance degradation of less than 7%	Case-by-case	Predict heat pipe lifespan under specific operating conditions
6	Continuous Life Test	Continuous testing under normal operating conditions	Case-by-case	Measure actual lifespan until failure
7	Thermal Cycling Test	Temperature cycles from -30°C to 120°C (or -55°C to 125°C) over 10 hours	Case-by-case	Evaluate performance degradation or structural deformation

Heat Pipe Heat Sinks

With custom heat pipes, we also make custom heat pipe assemblies. Please visit our Heat Pipe Heat Sinks page for more information.