WCN3950 004 Wifi iC

Every GSM technician eventually gets a phone where WiFi refuses to turn on, or turns on and drops the connection within seconds. Before blaming software, check the board — on Redmi Note 8, Redmi Note 4, Redmi 6 Pro, and Mi A1 units, the WCN3950-004 is usually the part responsible for that exact symptom.This chip is a single-die combo IC from Qualcomm's WCN39xx family. It packs WLAN, Bluetooth, and FM support into one 58-pin WLPSP package, which is why a single failed solder joint or a moisture-damaged pad can wipe out WiFi, Bluetooth, and FM tuner function together. If you're troubleshooting a board where all three symptoms show up at once — no WiFi networks detected, Bluetooth pairing fails, FM radio app crashes — that pattern points straight at this IC rather than three separate faults.On the wireless side, it covers 802.11 a/b/g/n/ac standards across both 2.4GHz and 5GHz bands, so a working chip gives the phone dual-band capability rather than 2.4GHz-only performance. On the Bluetooth side, it supports BT5.0 qualification, covering both classic Bluetooth and BLE profiles used by earbuds, smartwatches, and file transfer.Power draw sits low, in the roughly 0.5W dissipation range, running off a 1.5V–5V input rail depending on board design. That low draw matters on the bench too — if you're seeing abnormal current spikes near this IC's footprint during a short-circuit test, that's a strong sign the chip itself has shorted internally rather than a fault elsewhere on the board.Reballing this chip needs the same discipline as any fine-pitch BGA/WLPSP job. Cover the surrounding area with heat-insulation tape, hold the board steady in a catcher, apply flux evenly, and keep hot air under 350°C to avoid lifting neighboring pads or warping the PCB. After removal, clean the footprint thoroughly before reballing and reflow — a rushed cleaning job is the most common reason a "new" IC still shows a dead WiFi toggle after replacement.Where this IC sits in the repair workflow: it's a board-level component replacement, not a software fix. If a customer's phone shows "WiFi not turning on" but the toggle itself responds and just won't scan, run a software reset first — reflash and clear network settings before assuming hardware fault. If the toggle is greyed out entirely, doesn't respond, or the phone shows no WiFi hardware detected in engineering mode, that's your confirmation to move to IC-level diagnosis and reballing.Buy genuine, tested stock rather than pulled or reused chips for this job. A WCN3950-004 with hairline internal damage can pass a visual check and still fail intermittently after reflow, sending the phone back to your bench within days. For a repair shop working through a steady stream of Redmi WiFi complaints, keeping verified WCN3950-004 stock on hand cuts diagnosis-to-delivery time significantly, since this single IC accounts for a large share of WiFi hardware faults on these specific models.Pair this IC with a quality hot air station, fine-tip tweezers, flux paste, and a stencil matched to the 58-pin WLPSP footprint for a clean, repeatable reballing job every time.