Custom Heat Pipes
Heat pipes are initially manufactured in round shapes, but can be customized through a series of bending and flattening processes to form 2D or 3D shapes. Customized heat pipes can transfer heat from the source to almost anywhere that the design requires. Examples of thermal solutions using custom heat pipes can be found on this page.
What We Can Manufacture
For custom, copper heat pipes, we can produce different diameters and lengths. Most common diameters are 4mm, 5mm, 6mm, 8mm, and 10mm. Lengths can also range from 80mm to 500mm. Working fluids can either by H20 distilled water or CH3OH methanol. For surface finishes, we offer anti-oxidation and nickel plating. Nickel plated finishes are great for soldering heat pipes to aluminum parts.
H2O Distilled Water Working Fluid
- For above-room temperature (20°C) applications
- Operating temperature: 1°C to 325°C
CH3OH Methanol Working Fluid
- For low-temperature applications
- Operating temperature: -75°C to 120°C
- Does not freeze as easily as water
Other types of working fluids are not compatible with copper heat pipes.
Types of Wick Structures
A capillary wick made of sintered powder that adheres to the inner walls of a heat pipe.
- High performance
- Works best against gravity
A copper tube with a series of shallow grooves on the inside of the heat pipe.
- Light weight
- Low costs
Rapid Prototyping of Custom Heat Pipes
We offer rapid prototyping services for custom heat pipes. If tooling is not required, prototypes can be made in about 1 week. For parts that require special tooling, the turnaround time is about 2 weeks. The lead time will depend on the design of the heat pipe. Please contact us for more information.
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 smart phones, 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.
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|
|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|
To Calculate Width
W = Width of Heat Pipe
D = Diameter of Heat Pipe
T = Thickness of Heat Pipe (when flattened)
After flattening, heat pipes cannot by bent out-of-plane (no exceptions). Heat pipes can only be bent out-of-plane when the heat pipe is round.
Heat Transfer Capacity
Effective Thermal ConductivityWith 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
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 Capability
|Heat Pipe Shape||Cross-sectional|
|Heat Transfer Rate
|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|
Heat Pipe Tester (LW – 9354)
With Long Win’s LW-9354 heat pipe performance tester, we can evaluate the performance of heat pipes with different testing conditions. The principle of the heat pipe testing equipment is to set a simulated heating source at one end of the heat pipe, and set a cooling device at the other end of the heat pipe to simulate the heat sink. We can then measure the temperature difference between the hot and cold ends of the heat pipe (∆T=Thavg − Tcavg) through the heat absorbed by the heat pipe (Q), the thermal resistance (R) and equivalent thermal conductivity (Keff) of the heat pipe can be calculated. We can evaluate the thermal performance steady-state of a heat pipe, thermal resistance measurement of a heat pipe at different angles and the thermal response rate of a heat pipe.
Tests Available:1. Thermal Performance Steady-State Test
2. Thermal Resistance Measurement at different Angles
3. Thermal Response Rate Measurements
Steady–State Test and Curve
Place the test object between the heating end and the condensation end.
Input heat from a controllable heat source and remove the heat from the water cooling through the specimen.
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.
Thermal Resistance of Heat Pipes Example
Heat pipes with larger diameters transfer more heat than heat pipes with smaller diameters. Shorter length heat pipes can also transfer more heat than heat pipes with longer lengths.
Heat Pipe Power at Different Angles Example
Below are the results of a 6mm diameter and 200mm length heat pipe tested at different angles using the attitude adjustment device.
Thermal Response Rate Example
Tt: Water Temperature
Tc: Heat Pipe Temperature
The thermostatic water is set to 65°C The initial temperature of the heat pipe is approximately ~20°C. After about7 seconds, the hot end temperature rises to about ~55°C and approaches steady state.
|No.||Test Item||Test Conditions||Sampling Ratio||Purpose|
|1||High Temp. Aging Test||Ambient Temp. 210 C for 12 hr||100%||Leakage check & aging|
|2||Thermal Response Test||Insert 1/3 – ½ length of pipe into 50°C water. The temp of other end shall rise to standard value in 25 seconds.||100%||Vacuum & leakage check|
|3||Qmax Test||Heating Length = 25-35mm, Test temp = 60°C||100%||To measure the max. heat transfer rate|
|4||Rth Thermal Resistance Test||Fix heat transfer rate and measure temp. difference of heat pipes||>1pcs/2hr||To ensure thermal resistance of each pipe be lower than spec|
|5||Accelerated Life Test||140 C for 1000hr. Performance decrease by less than 7%||By case||To predict life of heat pipe at certain operating temp.|
|6||Continuous Life Test||Continuous testing at normal operating conditions||By case||To measure actual life of heat pipe until failure occurs|
|7||Thermal Cycling Test||Temp. varies from -30 C to 120 C in 10hr, 600 cycles||By case||To measure performance variation after thermal cycling|
Heat Pipe Assembly
With custom heat pipes, we also offer custom heat pipe assemblies. Please visit our Heat Pipe Assemblies page for more info.