Broken or cracked glass on a smartphone screen is not only an aesthetic problem, but also a risk of further damage to the matrix. Owners of Xiaomi and Redmi devices often face a situation where the touchscreen works properly, and the image is not distorted, but a web of cracks flaunts on top. In service centers, you can ask for a replacement of glass amount up to 70% of the cost of the device itself, although the actual cost of consumable material is much lower.
Self-replacement allows you to save a lot of money, but requires accuracy, patience and understanding of the design of the display module. Modern smartphone screens are a complex "sandwich" of polarization film, touchscreen, glass and matrix glued together with a special optically transparent glue OCA. Violation of the technology of warming up or careless movement can lead to the death of the matrix, so it is important to follow the algorithm of actions.
Before you start disassembling, you need to make sure that the problem lies in the outside glass. If there are black spots, stripes, or the sensor does not respond completely to touch, it is a matter of damage to the entire display module. In this case, replacing only the glass will not help, and you will need a complete replacement of the screen assembly. If the matrix is intact, and only the top glass is broken, then self-repair is quite possible with basic skills.
Diagnosis of damage and selection of components
The first step is to make a thorough visual inspection of the device when the screen is on, to check if there are black ink under the cracks that spread when pressed, which is a sure sign that the liquid matrix (IPS or OLED) is damaged, and it is also worth checking the multi-touch operation by drawing circles in the special Xiaomi engineering menu.
When choosing a new glass, it is important to pay attention to the quality of the oleophobic coating and the thickness of the material. Cheap analogs often have less strength and quickly lose their properties, becoming slippery or matte. Original or quality copies (OEM) provide better color transfer and sensor sensitivity. Poor quality glass can have the wrong refractive index, which will make the picture cloudy.
It's critical to get the right OCA (Optically Clear Adhesive) glue. The use of universal glue, or worse, superglue (cyanacrylate), is strictly prohibited. Superglue crystallizes, leaving visible slicings, and over time turns yellow, completely destroying the readability of the screen. The OCA glue remains transparent and elastic, compensating for micro-strokes.
⚠️ Attention: If cracks deep and sharp edges of the glass protrude outside, before any manipulations, carefully seal the screen with transparent tape. This will prevent injury to the fingers and glass crumbs from entering the body during disassembly.
- 📱 Original glass – ensures a perfect fit and no sensor sensitivity issues, but costs more.
- 🔧 Components OEM — Often produced in the same factories as the original, but without the brand logo, being the middle ground in price and quality.
- 💰 Budget analogues - may have a smaller thickness or worse oleophobic coating, which will affect tactile sensations.
Tools and workplace preparation required
To successfully perform the glass replacement procedure on Xiaomi Redmi, you will need a specific set of tools that goes beyond the standard household screwdriver. The main tool for separating glass and matrix is a separator (glass divider) or, in the budget version, a heating platform. The use of a hairdryer is permissible only in the initial stages of removing the module, but not for separating the glass from the matrix, since it is difficult to control the uniformity of heating.
Any speck of dust, villi or grain of sand that gets between the layers of glass and matrix during the gluing process will remain there forever and be visible as a black dot. It is recommended to use a laminar (a special air filter box) or assemble an improvised camera from a transparent film.
The basic set of the master includes: a thin string (nichrome or tungsten) for cutting glue, a set of plastic shoulder blades, suckers, tweezers with curved ends and UV-glue polymerization lamp (if used) UV-type OCA). High-purification isopropyl alcohol is also needed to remove residues of the old adhesive. Metal tools should be used with extreme caution to avoid damaging the plumes.
☑️ Toolkit assembly
Dismantling of the display module
The process begins with turning off the smartphone and retrieving it. SIM-Depending on the Redmi model (Note, Pro, K-series), the back cover can be glass or plastic. Glass covers require more careful heating around the perimeter. Once the glue is softened, the cover is removed using a suction cup and a plastic card. Next, you need to unscrew all visible screws that fix the plastic frame or protective plate of the motherboard.
The next step is to turn off the plumes. Carefully bend the safety strips, you need to turn off the main display module plume, the touchscreen plume (if it is displayed separately) and the plume of the underscreen fingerprint scanner. Often the plumes are glued, so they need to be slightly warmed up with a hairdryer before pulling off. After disconnecting all communications, the module is removed from the case.
At this stage, the module is a single unit. If the replacement is done by pasting (while maintaining the native matrix), the module is placed on the heating platform. 80-90 It's about a degree Celsius. 3-5 minutes to soften the layer OCA-It's important not to overheat the matrix, especially if it's like, OLED, Because they are sensitive to high temperatures.
Recommended temperature conditions for heating:
- To remove the module from the housing: 80-90 °C (3-5 minutes)
- For separation of glass: 80-85°C (5-7 min)
- Table temperature during gluing: 30-40 ° C⚠️ Warning: Never attempt to smack glass with a blade or metal blade without first warming up. OCA has high adhesion, and when mechanically exposed, the matrix is guaranteed to crack or the internal structure of the pixels will be damaged.
Separation process: separation of glass from matrix
Separation is the most critical and risky part of the repair process. Once warmed up, the module is fixed to the vacuum table of the separator. A thin nichrome string stretched on the frame is neatly inserted into the gap between the broken glass and the matrix. The movements must be smooth, without jerking, with constant monitoring of the depth of the string's immersion. The string must cut off the glue layer without touching the polarization film of the matrix.
When you're working with a string, you need to be careful about the angle of inclination, and if you're going to get a string too deep, it's going to cut the touchscreen tracks or it's going to damage the matrix itself, leaving black stripes in the image, and if you're going to run the string too close to the glass, you can't cut the glue completely, which will cause the matrix to break when you try to remove the glass. And experienced craftsmen use a magnifying glass or a microscope to control the process.
Once the string has passed the entire perimeter, the glass is carefully removed, and the surface of the matrix will remain the residue of OCA glue. Removing them requires delicacy. The old glue can be rolled with a finger (using the stickiness of a new layer of glue or a special rubber roller) or carefully cut with a blade at an angle. The cleaning process must be carried out in maximum purity, because the sticky surface instantly attracts dust.
What do I do if the string is stuck?
Cleaning the matrix and applying new glue
After removing the main glue residues, the matrix surface is wiped with a napkin abundantly moistened with isopropyl alcohol. The movements should be light, without strong pressure. Then the surface is polished with a dry, lilaless napkin to the perfect state. Any scratch on the polarization film will be visible to the lumen after the new glass is installed.
The new layer uses a special pattern (mask) corresponding to the model of the smartphone, or the method of manual sticking (for experienced ones). OCA glue is sold in rolls or ready-made sheets. When applied manually, it is important to avoid air bubbles. The process of rolling with shafts or using a vacuum chamber allows you to expel air from under the layer of glue. Air bubbles not only impair visibility, but can also become points of concentration of tension, leading to new cracks.
If you use adhesives that require ultraviolet polymerization, it is important to observe the exposure time. UV-The glue will remain liquid and float when the phone is heated, and the extra time can make the adhesive layer too rigid and brittle. 2-3 minutes on each side, but depends on the power of the lamp and the type of glue.
| Parameter | Description | Impact on outcome |
|---|---|---|
| OCA thickness | Usually 0.10 mm - 0.15 mm | Thin glue is better for sensitivity, thick hides scratches |
| Hardness (Hardness) | Measured by Shore. | Affects shock amortization and scratch resistance |
| Transparency | Light transmission coefficient | Determines the brightness of the screen and the saturation of colors |
| adhesion | Clutch strength | Ensures that the glass will not peel off over time |
💡
Use a special liquid to remove OCA (De-bonder) only on the edges of the matrix. The introduction of chemistry on the central part of the working region of the matrix can cause irreversible chemical reactions and stains.
Final assembly and performance check
Once the new glass with the applied glue is installed on the matrix, it is necessary to remove the excess glue protruding at the edges, this is done carefully with a blade or scissors after preliminary "grabbing" the glue in the UV-lamp-lamp 10-15 Then you have a full polymerization, and you put the finished module in the frame to test it.
Before the final sealing of the case, you need to connect all the plumes and turn on the smartphone. Checked are: uniformity of the backlight (no "lights"), the touchscreen over the entire area, the reaction to the multi-touch, the operation of the proximity sensor and the fingerprint scanner. Particular attention should be paid to the edges of the screen - often with poor gluing touchscreen ceases to work in the areas of rounding (2.5D).
If all tests are successful, the module is locked in the case, a new layer of sealant glue (B-7000 or special double-sided tape) is applied along the perimeter of the frame to provide moisture protection (at least basic) and fix the screen. The smartphone is left under press or in tight gum for several hours until the fixing glue is fully polymerized.
⚠️ Note: After assembly, do not rush to install a protective film or a case with high sides in the first 12-24 The glue that holds the module in the case must dry completely, otherwise the screen may displace or detach when carried in the pocket.
- ✅ Zigzag test – zigzag your finger across the screen to make sure there are no dead zones.
- 🎨 Color check – turn on the white image and inspect the screen for yellow spots or uneven backlights.
- 🔊 Audio test – make sure that the plume of the lower speaker or conversational speaker is not compressed during the assembly.
💡
The main secret of success is cleanliness. 90% of the defect when gluing glasses is due to dust caught between the layers, and not because of the breakdown of the matrix in the process of work.