Understanding the Physical Footprint of a 1.14 Inch Display Module
The footprint of a 1.14 inch display module is not a single number—it’s a combination of the active area, the glass outline, the PCB dimensions, and the connector placement. For the most common variant, the 1.14 inch 240x135 ips display, the active area measures exactly 24.912 mm wide by 14.112 mm tall, which gives you a diagonal of about 28.7 mm (1.13 inches). The glass outline, which includes the border around the active pixels, is typically 27.5 mm by 18.0 mm, with a thickness of around 1.1 mm for the glass alone. But the real footprint you need to worry about for mechanical design is the PCB or FPC (flexible printed circuit) breakout board. For a standard module with an integrated FPC, the total board dimensions often come in at 30.0 mm by 22.0 mm, with the FPC tail extending about 12 mm beyond the edge. The connector itself—usually a 0.5 mm pitch, 12-pin or 14-pin ZIF socket—adds roughly 6.0 mm of width and 2.5 mm of depth beyond the PCB edge. So if you’re designing a case or enclosure, you need to account for at least 36 mm by 24 mm of clearance, plus a 5 mm buffer for cable routing.
Let’s break down the numbers further. The resolution is 240x135 pixels, which at this size gives a pixel density of about 210 PPI (pixels per inch). That’s sharp enough for clear text and icons, but not as dense as a smartphone display. The active area itself is a rectangle with an aspect ratio of 16:9, which is unusual for such a small display—most tiny modules use 4:3 or 1:1. That 16:9 ratio means the width is almost 1.76 times the height, so if you’re mounting it in a circular or square cutout, you’ll have significant dead space on the sides. The glass border around the active area is 1.3 mm on the left and right, and 1.9 mm on the top and bottom, which is typical for a COG (chip-on-glass) design. The bottom border is slightly larger because that’s where the driver IC is bonded—usually a ST7735S or similar controller, which adds about 0.5 mm to the glass thickness in that region. The total module thickness, including the backlight and the polarizer, is 2.4 mm to 2.8 mm, depending on whether you have a metal frame or just a plastic bezel. The backlight itself is a single LED, typically drawing 20 mA at 3.0 V, and it adds about 0.6 mm to the stack-up.
Now, let’s talk about the PCB footprint. If you’re buying a breakout board for this display, the dimensions are usually 32.0 mm by 24.0 mm with a 2.0 mm hole in each corner for mounting screws. The PCB thickness is 1.0 mm, standard FR4. The FPC tail is 0.8 mm thick and has a width of 12.0 mm for the 12-pin version, or 14.0 mm for the 14-pin version. The connector on the FPC is a 0.5 mm pitch, 12-position ZIF with a locking tab, which adds about 3.0 mm to the length of the tail. The total length of the FPC from the glass edge to the connector tip is typically 25.0 mm, but you can get custom lengths from some suppliers. The electrical interface is SPI, using 4 wires (CS, DC, SCK, MOSI) plus power and ground, so you only need 6 pins minimum, but the extra pins are for backlight control, reset, and optional MISO. The SPI clock speed can go up to 20 MHz, which gives you a full frame refresh in about 1.5 ms at 240x135 resolution with 16-bit color. That’s fast enough for simple animations, but not for video.
Thermal footprint is another angle. The display module itself dissipates very little heat—the backlight LED is the main heat source, at about 60 mW (20 mA at 3.0 V). The driver IC consumes around 5 mW during active operation, and 0.1 mW in sleep mode. So the total thermal load is under 100 mW, which means you don’t need a heatsink or airflow. But if you’re mounting it in a sealed enclosure, the internal temperature could rise by 2-3°C above ambient, which is fine for the display’s operating range of -20°C to +70°C. The storage temperature is wider, from -30°C to +80°C. The glass itself has a coefficient of thermal expansion of about 3.5 ppm/°C, so a 50°C temperature swing will cause a dimensional change of about 0.005 mm in the width—negligible for most applications.
Mechanical mounting considerations: The display glass is fragile, so you need to support it properly. The recommended mounting method is to use a 0.5 mm thick adhesive foam gasket around the perimeter of the glass, with a cutout for the active area. The foam should be 2.0 mm wide and have a compressive modulus of 0.1 MPa to avoid cracking the glass. The PCB should be mounted with M2 screws at 2.0 N·m torque, using nylon washers to prevent galvanic corrosion. The FPC should be bent with a radius of at least 3.0 mm to avoid damaging the copper traces. If you’re using a metal frame, make sure it’s grounded to the PCB ground plane to reduce EMI—the SPI bus can radiate at 20 MHz, and the display’s backlight driver can cause ripple on the power line. A 100 nF ceramic capacitor placed close to the display connector on the main PCB will filter most of that noise.
Let’s look at the optical footprint. The display uses an IPS (In-Plane Switching) panel, which gives 85° viewing angles in all directions (typical). The contrast ratio is 800:1 (typical), and the brightness is 300 cd/m² (typical) with the backlight at full power. The color gamut is 65% of NTSC, which is decent for a small display. The response time is 25 ms (typical), which is fine for static images but will show ghosting on fast-moving content. The pixel arrangement is RGB stripe, with a sub-pixel pitch of 0.104 mm (104 µm). That means each pixel is about 0.1 mm wide, which is visible to the naked eye if you hold it close, but at a typical viewing distance of 30 cm, it looks sharp. The surface finish is glossy, with a reflectivity of about 8%, so you’ll need an anti-glare film if using it in bright sunlight. The polarizer is linear, which means you’ll see color shifts if you view it through polarized sunglasses at certain angles.
Power consumption footprint: The display draws 5 mA at 3.3 V for the logic (16.5 mW), plus the backlight current. The backlight can be PWM-controlled at 1 kHz with a duty cycle from 0% to 100%. At 50% brightness, the backlight draws about 10 mA (30 mW), so total power is around 46.5 mW. At full brightness, it’s 76.5 mW. In sleep mode, the display draws 0.1 mA (0.33 mW). So if you’re running on a 200 mAh battery, you can expect about 4.3 hours of continuous operation at full brightness, or 7.1 hours at 50% brightness. That’s not great for battery-powered devices, but you can extend it by using a low-power mode that turns off the display after a few seconds of inactivity. The driver IC supports a partial display mode that only updates a portion of the screen, which reduces power by about 30%.
Now, let’s talk about the mechanical tolerances. The glass outline has a tolerance of ±0.2 mm in width and height, and ±0.1 mm in thickness. The active area position relative to the glass edge has a tolerance of ±0.3 mm. So if you’re designing a cutout for the active area, you need to allow for at least 0.5 mm of clearance on each side to avoid clipping the image. The FPC connector position has a tolerance of ±0.5 mm relative to the glass edge. The PCB mounting holes have a tolerance of ±0.1 mm for the hole diameter (typically 2.0 mm +0.1/-0.0), and the hole positions have a tolerance of ±0.2 mm. So if you’re using a 3D-printed enclosure, you should design the mounting posts with a 0.3 mm gap around the screws to allow for these tolerances.
Let’s get into the electrical footprint. The SPI interface uses 3.3 V logic levels, but it’s 5 V tolerant on the input pins (CS, DC, SCK, MOSI). The output pin (MISO) is 3.3 V only. The backlight pin is a constant current sink, so you need to connect it to ground through a resistor to set the current. The typical resistor value is 10 ohms for 20 mA, but you can adjust it to get different brightness levels. The reset pin is active low, and it needs a 10 kΩ pull-up resistor to 3.3 V. The power supply should be clean—a 100 µF electrolytic capacitor plus a 100 nF ceramic on the VCC pin is recommended. The display draws a peak current of 50 mA during initialization (when the driver IC is resetting), so your power supply should be able to handle that spike. The operating voltage range is 2.8 V to 3.6 V, so you can run it directly from a lithium-ion battery (3.7 V nominal) with a series diode to drop the voltage, or use a 3.3 V LDO regulator.
Finally, let’s look at the environmental footprint. The display contains 0.5 grams of glass, 0.2 grams of plastic (the bezel and FPC), and 0.1 grams of metal (the backlight frame and connector pins). The total weight is about 0.8 grams for the bare module, or 1.2 grams with the breakout PCB. The display is RoHS compliant, with no lead, mercury, or cadmium. The backlight LED is a InGaN blue LED with a phosphor coating, which gives a white color temperature of 6500K (typical). The LED has a lifespan of 50,000 hours at 20 mA, which is about 5.7 years of continuous use. The driver IC is manufactured on a 0.18 µm CMOS process, which is energy-efficient but not the most modern. The IC contains 240x135x18 bits of SRAM (about 58 KB) for the frame buffer, plus a command decoder and timing controller. The chip is bonded to the glass using anisotropic conductive film (ACF), which is a standard process for COG displays. The display is packaged in a carrier tape for automated assembly, with a reel diameter of 330 mm and a hub diameter of 100 mm. Each reel holds 500 units.
If you’re designing a product around this display, the footprint is more than just the physical dimensions. You need to consider the electrical, thermal, optical, and mechanical interfaces. The 1.14 inch 240x135 ips display is a good choice for wearables, smart home devices, and small IoT gadgets because of its low power, small size, and decent resolution. But the mechanical design has to account for the FPC bending radius, the glass fragility, and the connector clearance. The optical performance is acceptable for indoor use, but you’ll need a backlight boost or a transflective film for outdoor readability. The SPI interface is easy to implement with any microcontroller, but you’ll need to manage the backlight power to extend battery life. The thermal footprint is negligible, but the electrical noise from the SPI bus can affect nearby sensors, so keep the traces short and add a ground plane. The environmental footprint is small, but the display is not recyclable due to the ACF bonding and the glass-metal composite. The cost is about $3 to $5 per unit in low volumes, dropping to $1.50 to $2.00 in quantities of 1000 or more. The lead time from Chinese suppliers is typically 4 to 6 weeks for custom orders, or 1 to 2 weeks for stock items. The display is available from major distributors like DigiKey, Mouser, and LCSC, but the best price is usually direct from the manufacturer.