The article explains how the material of the mobile phone you are holding has evolved from aluminium alloy totitanium, For consumers, the term “changing the casing” is merely a line in the product description. However, for welding workshops, it means that the entire process must be completely restarted; each material differs in terms of laser absorption rate, thermal conductivity and coefficient of thermal expansion, and laser welding is the only joining technology capable of keeping pace with the speed at which materials are updated.
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The 16 Pro you’re holding has a titanium alloy frame.
You may have noticed that it feels lighter and has a more textured finish. However, you have most likely never given much thought to one question: just how was this titanium alloy mid-frame actually welded in place?
The answer is that this bears no resemblance whatsoever to the welding process used for the previous generation of aluminium alloy frames; it is not simply a matter of adjusting a few parameters, but rather a complete redevelopment of the entire process.
In 2021, the company undertook aluminium alloy welding operations; by 2024, it had switched to welding a combination of stainless steel and aluminium alloys; and in 2026, it began welding titanium alloys—having switched between three different generations of materials over the course of three years, the welding production line was consequently reprogrammed three times.
The next generation of foldable screens and AR glasses will be made from a combination of titanium alloys, carbon fibre and zirconium alloys. By then, the frequency with which welding processes are revised is likely to shift from “once every two years” to “once a year”.
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Aluminium alloy is like a sponge; titanium alloy is like modelling clay.
When placed under a laser, the two metals behave in completely opposite ways:
Features
Aluminium alloy (mainstream for 2021–2022)
Titanium alloy (standard specification for high-end models, 2025–2026)
Absorption coefficient for infrared lasers
~7% (very low)
~30% (medium)
Thermal conductivity
High (rapid heat diffusion)
Extremely low (approximately 1/15th that of aluminium)
Welding performance
Most of the laser energy is reflected, but once it is absorbed, the heat spreads very quickly—just like a sponge.
When the laser beam is directed onto the surface, absorption is excellent; however, there is virtually no heat diffusion, and all the heat accumulates at the weld point, much like modelling clay.
The most common problems
Unable to weld (insufficient energy)
Burnt through (all the heat concentrated in one spot)
Consequently, the parameters used for welding aluminium alloys were applied directly to the welding of titanium alloys, with the result that either welding was impossible or burn-through occurred.
For a welding plant, switching to each new material is like ”starting from scratch”:
Material Iteration
Time
The impact on welding production lines
Aluminium alloy → Stainless steel
2022-2024
Welding dissimilar materials is twice as difficult; the difference in thermal expansion coefficients between 501TP3 and T is such that separate parameter matching is required.
Stainless steel → Titanium alloy
2025-2026
With thermal conductivity dropping by as much as 15-fold, heat management during welding has shifted from “adding energy” to “controlling energy”, marking a reversal in the underlying logic.
Titanium alloys → Composite materials
2026+
Wall thickness reduced to less than 0.3 mm; mixed-material welding; heating elements integrated into structural components
Q: If we switch to a different material, does that mean we can no longer use the existing equipment? Would it not be possible to simply replace the welding head?
That’s right; it is not a hardware issue, but rather a problem arising from the parameter system. Each metal has a different laser absorption rate, thermal conductivity, melting point and coefficient of thermal expansion. A set of welding parameters—including power, pulse width, defocus amount and speed—was developed specifically for aluminium alloys and took half a year to stabilise; however, when switched to titanium alloys, they all became ineffective, due to changes in the underlying physical properties. This is not a problem that can be solved simply by “changing the welding head”; rather, it involves “re-establishing the correlation between the parameters and quality”. The validation cycle for this process generally takes between three and six months.
Q: Aluminium alloy remains the mainstream material for mobile phone frames at present, with titanium alloy only found in a small number of high-end models. Is it necessary for welding factories to start making preparations now?
Answer: Consider two trends. The first concerns the evolution of 3C materials: the progression from the aluminium alloy used in the X model to the stainless steel in the 14 Pro, and on to the titanium alloy in the 16 Pro—a trajectory that is irreversible. The second concerns next-generation solutions for foldable screens and AR glasses, where ultra-thin titanium alloy combined with carbon fibre has already been established as the definitive route. With wall thicknesses decreasing from the 1 mm range to the 0.3 mm range, the demands on welding precision are rising exponentially. Welding factories that have not yet built up the necessary technical capabilities will find that, by the time titanium alloy mid-frames transition from being a “high-end exclusive” to a “mid-range standard”, a validation cycle of three to six months will be sufficient for orders to flow to those who are prepared.
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Brazing, adhesive bonding, ultrasonic welding: why have they all fallen behind?
The evolution of materials is not limited to laser welding alone; as far as the welding methods used with traditional media are concerned, this effectively blocks the way entirely.
Welding methods for media
The Challenges Facing Titanium Alloys
Root cause
Brazing/Soldering
The oxide film present on the surface of titanium alloys is extremely stubborn; under these conditions, flux is unable to remove it effectively, and high temperatures would damage the fine microstructure of the titanium alloy.
Titanium’s chemical inertness renders the flux ineffective
Adhesive
The adhesive durability of aluminium alloys is considerably greater than that of titanium alloys; after three months, the bond strength of titanium alloys decreases from 40% to 60%, whereas this is not the case with aluminium alloys.
Titanium surfaces are chemically inert and have poor adhesive bonding properties
Ultrasonic welding
Titanium alloys are very hard, and tool tips wear 5–8 times faster than when welding aluminium.
Poor physical hardness makes the project economically unviable
Diffusion welding
Requires 800–1000 °C + high vacuum + several hours
3C products cannot afford to wait for this production pace
All four traditional approaches have failed in the face of titanium alloys.
The fact that laser welding remains the only viable option is not because “lasers are superior”, but because the parameter system for laser welding consists of independent digital variables. When switching to a different material, there is no need to reinvent the process, seek out new materials, or replace equipment; one simply needs to retrieve a set of parameter combinations from the parameter library that have already been validated for the new material.
Changing the brazing material means having to source a new brazing alloy, as different materials require different alloy compositions; it also necessitates redefining the furnace temperature profile and conducting multiple rounds of process validation, a process that takes three to five times as long as laser welding. In the mobile phone industry, where materials are typically updated every two years, such a disparity in speed can prove fatal.
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The materials will keep changing, and the parameters can be adjusted at any time.
When welding aluminium alloys, a specific set of parameters must be used; when welding stainless steel, a different set of parameters must be applied; when welding titanium alloys, a third set of specialised parameters must be selected; and when welding dissimilar materials such as titanium and stainless steel, a fourth set of parameters is required.
Behind every set of parameters lies data accumulated through dozens, or even hundreds, of rounds of process validation. This data is not a one-off; it constitutes an asset. With every material validated, another piece is added to the jigsaw puzzle that is the parameter library. When a new material emerges, we do not start from scratch, but rather seek the closest starting point from the existing puzzle pieces, and then make adjustments.
This is why laser welding is currently the only joining technology capable of keeping pace with the rapid evolution of 3C materials. It is not because the equipment is more expensive or more advanced, but because it has transformed welding from a craft into a digital system with iterative capabilities.
IT LASER has accumulated extensive experience in the field of precision 3C welding, having worked with multiple generations of materials including aluminium, stainless steel, titanium alloys and copper alloys.Process parametersKu’s QCW pulsed laser systems are capable of providing independently validated welding process packages for every material combination; there is no need to redevelop parameters when switching from one material to another. This represents a practical advantage derived from the digital accumulation of expertise in precision laser welding, and also marks IT LASER’s expansion from its precision marking business into the core competence of multi-material precision welding.
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[Key Conclusions]
· The materials used in 3C electronic products are rapidly evolving from aluminium alloys to stainless steel, then to titanium alloys, and subsequently to composite materials; Each generation of material change means that welding processes must be rebuilt from scratch. The cycle for replacing materials in brazing is three to five times longer than that for laser welding; at a pace of “one generation change every two years”, this disparity plays a decisive role.
Aluminium alloys and titanium alloys exhibit entirely opposite physical behaviours during laser welding, presenting states akin to “sponge” and “plasticine” respectively. Changing the material is equivalent to altering the underlying parametric logic; it is not a problem that can be resolved simply by “turning a few knobs”.
· The brazing process was blocked by the titanium alloy, adhesive bonding was blocked by the titanium alloy, ultrasonic welding was blocked by the titanium alloy, and diffusion welding was blocked by the titanium alloy, leaving all four methods completely blocked; only laser welding, with its digital, independent parameter system, has kept pace with the evolution of the material.
Competition in precision welding is, in essence, a competition over “process parameter libraries”; the more material-to-parameter mappings a company has accumulated, the faster it will be able to respond when new materials emerge. This is not a contest between pieces of equipment, but a battle over data assets.
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