Quick Q&A: How Are Leak Tests Conducted on Liquid-Cooling Plates and Copper Tube Assemblies? Jingcheng Engineering’s Comprehensive Guide to Applications in the Liquid-Cooling Industry

Leaks in liquid-cooling systems are often not immediately apparent.

Leaks may be hidden at bends in copper tubing, at weld seams, or at the mating surfaces of fittings and valve bodies. These locations are difficult to detect with the naked eye, but changes in pressure don’t lie.Filling the cavity with gas at a certain pressure to see if the pressure drops is currently the most reliable testing method on the production line.The

JCGK, a leading domestic manufacturer of airtightness testing equipment, has completed numerous practical projects in the liquid cooling industry, involving airtightness testing for products such as liquid cooling plates, copper tube assemblies, and heat sinks. Since each product has a different structure, the testing methods, fixture designs, and automation solutions must be adapted accordingly. Below, we’ll outline the scenarios encountered in real-world applications and the approach to selecting the appropriate equipment.

Q1: Why is airtightness testing necessary in the liquid-cooling industry?

The core value of a liquid-cooling system lies inStable Circulation of the Coolant in a Closed Flow Channel. Whether in new energy vehicles, energy storage systems, or servers and data centers, if sand holes, cracks, or poor welds occur in liquid-cooling plates, copper tube assemblies, or quick-connect fittings, the cooling medium will leak.Leaks can result not only in failure of heat dissipation, but also in equipment damage and even safety incidents.The

Testing of liquid-cooled plates typically involves multiple aspects, including leak testing, pressure resistance, and heat dissipation performance,Leak testing is directly related to the long-term operational reliability of liquid-cooling systems.. For liquid-cooling manufacturers, airtightness testing is not merely a formality; it is a critical quality control step before a product enters mass production.

Q2: What types of products are typically tested in the liquid cooling industry?

As long as a product contains enclosed flow channels or sealed chambers, it may require an airtightness test.

Typical products include liquid-cooled plates, water-cooled plates, copper tube assemblies, cooling piping, liquid-cooling quick-connect fittings, liquid-cooling CDU units, manifolds, heat exchangers, liquid-cooling pumps, liquid-cooling valves, and other related components, as well as battery liquid-cooling system components and server liquid-cooling heat dissipation components.

Among these, welded structural products are particularly noteworthy. Take copper tube assemblies for liquid-cooling systems as an example: after being bent, these products form complex piping systems,What really needs to be inspected isn't the exterior, but the internal defects that are invisible to the naked eye.The

Q3: What exactly are we looking for during airtightness testing of copper tube assemblies?

Air-tightness testing aims to identify those areas that “appear to be fine” but are actually leaking.

Weld porosity is the most common hidden defect. Minuscule holes may exist in the welded areas that are completely invisible to the naked eye, but once the system is operational, coolant will seep out from these locations. Inadequate welding is another type of issue—a visually intact weld surface does not necessarily mean a reliable internal seal has been formed. Furthermore, processing irregularities during the bending and forming of liquid-cooled copper tubes can also create potential leakage pathways.

The essence of leak testing is to verifyIs this cooling channel a truly reliable sealed system?...and not just that it looks flawless.

Q4: What is the core logic behind Jingcheng Engineering’s liquid-cooling testing solution?

The core idea is A combined solution featuring “testing equipment + custom fixtures + multi-channel capabilities + automation interfaces”TheAir-tightness Testing Solution for Liquid-Cooled Copper Tubes: Due to a confidentiality agreement regarding the customer’s new, yet-to-be-released product, we are unable to showcase video examples.

A set of custom-made equipment demonstrated by Jingcheng Engineering (JCGK)Dual-Channel Direct-Pressure Airtightness Testing EquipmentFor example:Below isTwo-Channel Airtightness Tester, with two sets of inspection fixtures installed above, customized according to the customer's product design. This approach does not simply involve placing standard instruments on the production line, but rather redesigning the fixtures based on the actual dimensions, interface locations, and testing requirements of the liquid-cooled components.

Here is a key division of labor:Instruments are responsible for “measuring,” while fixtures are responsible for “ensuring that products are measured consistently.”. Both are essential, especially for liquid-cooled products with complex geometries.

Q5: Why do liquid-cooled components require custom tooling?

Liquid-cooled copper tube assemblies may involve bent tubing, multiple interfaces, varying product dimensions, and numerous weld locations, making it difficult for standard fixtures to directly meet mass production requirements. Fixtures must be designed to conform to the actual structure of the product, ensuring stable positioning and establishing reliable test boundaries.

For mass-production projects, the role of tooling is not limited to “Clamp the product", and it also relates toPositioning Consistency, Seal Stability, Test Repeatability, and even subsequent automated retrieval and placement.

There is one detail worth noting. The workwear in the case study deliberately retains the “Exposure"The space is not completely enclosed—this is to allow room for the robotic arm to automatically load and unload materials later on. If the equipment needs to be connected to "Robotic Arm + Airtightness Testing + Automatic Loading and Unloading"To implement a comprehensive solution, the tooling must take automation compatibility into account from the very beginning of the design process. A mature airtightness testing solution,From the very beginning of a project, you should consider both “how to test now” and “how to automate testing in the future.”The

Q6: Why are mass-production testing devices designed as “custom-built”?

Mass-production testing and laboratory testing are two completely different approaches.

In the lab, engineers manually place products, perform a test, and record the results. On the mass production line, products flow in continuously; robotic arms automatically pick them up and set them down; equipment performs continuous inspections; OK/NG determinations are made automatically; and data must be saved and traced in real time.

The core objective of mass-production testing is not “whether testing can be performed,” but rather “whether testing can be performed reliably, quickly, and continuously.” When a liquid-cooling project enters mass production, the equipment must simultaneously address a full range of issues, including inspection, fixtures, cycle time, loading and unloading, data management, and automation interfaces—and this is precisely where the value of custom automated inspection equipment lies.

Q7: Between the direct-pressure method and the differential-pressure method, which one should the liquid cooling industry choose?

When selecting a model, you can’t simply decide which method is best “Better", the key lies in the overall balance between test pressure, product volume, leakage standards, and accuracy requirements.

comparison dimension	direct pressure	differential pressure
Detection Principle	Observe the rate at which the pressure drops after inflation	Changes in the pressure difference between the reference chamber and the test specimen
(level of) sensitivity	Meets the requirements for most industrial leaks	Higher, suitable for detecting micro-leaks
Resistance to Environmental Interference	general	强
Applicable Scenarios	Mass-produced parts with a well-defined structure and established leakage standards	Precision parts with higher requirements for repeatability and minimal leakage
equipment cost	Relatively low	Relatively high
Mass Production Cycle Time	快	快

Precision Engineering JC-C10005 Differential Pressure Airtightness Tester, with a differential pressure range of ±5,000 Pa and a resolution of 0.1 Pa and 0.001 mL/min; it supports multi-channel configurations and is currently widely used in the mass production lines of leading manufacturers in the liquid cooling industry.

The correct approach to selecting a model is to first determine the product’s testing requirements and then decide on the testing principle, rather than selecting a specific equipment model first.

Q8: What are the six most important factors to consider when selecting a model?

test pressure

The equipment’s measurement range must cover the actual test pressure and allow for a reasonable process margin. Requirements for different liquid-cooled products—such as those rated at 100 kPa, 200 kPa, and 500 kPa—vary significantly; a single parameter cannot be applied to all products.

Leak Detection Criteria

This is the most critical parameter in the selection process. In this case, the requirement is ≤500 mL/min. If the customer requires a lower leakage rate, the detection principle and instrument accuracy must be reevaluated; the same solution cannot be used.

Product Internal Volume

Even with the same leakage standards, testing products with different volumes presents vastly different challenges. We cannot simply look at “What is the accuracy in Pa?", you need toProduct Volume, Test Pressure, Pressure Stabilization Time, and Test DurationEvaluate the situation as a whole.

Inspection cycle

For mass production projects, it is essential to first calculate the number of parts that need to be inspected per hour, and then work backward to determine the inspection time per part, the number of inspection lanes, the loading and unloading methods, and the automation cycle time. If the cycle time does not meet the target, the production line’s requirements cannot be met, no matter how optimal the other parameters may be.

Assembly Method

Liquid-cooled components have complex geometries, so it is essential to verify whether the manufacturer has the capability to design contour-following fixtures, enable rapid changeovers, support shared use across multiple products, and design automated fixtures. Fixture capabilities represent a hidden threshold that determines inspection stability and are often overlooked during the selection process.

Automation Interface

If the project will eventually integrate robotic arms, PLCs, or MES systems, it is important to confirm during the procurement phase that the equipment supports I/O, RS232/RS485, network interfaces, PLC communication, and MES data exchange.JC-TC rangeDirect Pressure Gaugecap (a poem) JC-C10005 rangedifferential pressure meterAll models feature RS232/485, I/O, and RJ45 network interfaces, and support barcode scanning and MES data integration.

Q9: Can a liquid-cooled plate, copper tube assembly, and heat sink all be part of the same solution?

The testing approach may be similar, but the parameters and fixtures usually cannot be directly copied.—This is a common pitfall when selecting engineering solutions.

Inspection of liquid-cooling plates focuses on flow channel seals and large-area structures with multiple interfaces; for copper tube assemblies, the focus is on weld porosity and tubing integrity; and for liquid-cooling quick-connect fittings, the focus is on the sealing condition of the interfaces and the structure of the valve cores. Just because these components are all part of the liquid-cooling industry does not mean they use the same inspection parameters.A truly professional solution must be tested and validated separately for each product category.

Q10: Why is the liquid cooling industry increasingly moving toward “leak testing + automation”?

Because liquid cooling is evolving from reliability issues with individual components toSystem-Level Reliability IssuesThe

Liquid-cooling systems involve a large number of critical sealing points, including liquid-cooling plates, piping, fittings, heat sinks, pumps, and valves. A problem with any one of these can affect the stable operation of the entire system. What manufacturers truly need is no longer just “Test once to see if there are any leaks", but ratherEvery product undergoes consistent testing, and the results of each test are recorded, traceable, and managed.The

This is why leak testing has evolved from standalone devices to a comprehensive system featuring multi-channel testing, automation, data traceability, and MES integration. Ultimately, product reliability depends on systematic quality management, not on a single test.

Conclusion

JCGK does more than just sell a single unit in the liquid cooling industry.airtightness meterThe

A liquid-cooled product was sent to us as a free sample. We first examined the product’s structure, confirmed the testing principle to be used, established the test parameters, and then designed the test fixture. Since the product has a complex shape, the fixture had to be custom-made accordingly. For large production runs, we’ll configure dual-channel or multi-channel setups. If robotic loading and unloading is required, we’ll include automation interfaces in the equipment design. For applications with strict micro-leakage requirements, we’ll evaluate differential pressure solutions. If quality traceability is needed, we’ll integrate with data systems.

When selecting a model, whether the instrument’s specifications are high is only one factor.Test to determine whether compatibility is achieved, whether the production fixtures are stable, whether the cycle time meets the standard, whether automation is feasible, and whether data traceability is possible....It is only when these factors are considered together that we can determine whether a solution is worthwhile.

When selecting a leak-tightness testing solution for products such as liquid-cooled plates, copper tube assemblies, liquid-cooling piping, or heat sinks, we recommend first clarifying your requirements across the above dimensions and then working with Jingcheng Engineering’s technical team to finalize a solution.

Original Statement:this paper was written byShenzhen Jingchenggongke Technology Co., Ltd.Written by the technical team, reproduced with attribution.Data sources: Precision Engineering internal test data and customer cases.