KRCONN Precision Charging Spring Contact, Reverse-Insert Assembly Type

• EPR348-03A50-01 Reverse-insert assembly-type precision charging spring contact

As smart wearables and miniature consumer electronics evolve toward extreme thinness and high-frequency fast charging, traditional contact components commonly face pain points such as large space occupation, easy dust accumulation, and elastic fatigue after prolonged use. To address these challenges, Krconn Technology Co., Ltd., leveraging its deep expertise in precision mold R&D and interconnect technologies, has officially launched Next-generation reverse-insert assembly-type precision charging spring contacts ( Model: EPR348-03A50-01 ) (Refer to the technical diagram above.) This product has now officially entered mass production. As a highly reliable miniature charging‑and‑data‑transfer contact assembly, it ingeniously integrates a reverse‑insertion assembly structure with a four‑fold mechanical protection design, all within an exceptionally compact footprint—body length 8.24 mm, tail‑wing width 5.12 mm, and overall height 3.48 mm. The spring contacts are crafted from industrial‑grade, high‑elasticity phosphor bronze, while the contact areas feature a premium thick gold plating, delivering a low‑impedance, ultra‑long‑life power‑interconnect solution for TWS Bluetooth earphone charging cases, smartwatches, and a wide range of portable smart devices.

  I. New Product Technical Specifications (This reverse-insertion assembled charging spring contact incorporates multiple innovations by Krconn in microstructural mechanics. It is integrally formed via precision molds, and its core technical design features the following four key highlights.)

(1) Integrated Stretching Arc-Surface Design

The top contact area is formed using a smooth, streamlined stretching process, resulting in a full, aesthetically pleasing appearance. This seamless, sharp‑free surface not only effectively reduces physical abrasion to mating terminals and contacts but also significantly eliminates hygiene dead zones, making it easy for end users to clean the contact surfaces during daily use and preventing poor contact caused by the buildup of sweat and sebum.

           (II) Interlocking Design for Wall Deformation Prevention

To address lateral impacts that may occur during automated assembly or equipment drops, the product’s central section innovatively incorporates an “interlocking anti-deformation” structure. Within a constrained 3.75 mm width, this design effectively prevents the side walls from buckling inward or outward under load, ensuring the long-term mechanical stability of the entire spring‑clip assembly.

(3) High-Precision Mold Locating Holes

A dedicated precision mold‑locating hole is provided in the tail transition zone (with a center‑to‑welding‑zone distance of 1.22 mm). On automated high‑speed reverse‑insertion assembly lines, this hole ensures impeccable alignment between the spring contacts, the plastic housing, and the leads, reducing assembly tolerances to the micrometer level and significantly improving the yield of the customer’s complete‑machine production lines.

(4) Safety Design for the Bottom Dead Center Protection

To address potential abnormal, forceful compression during use, or situations where the entire device is subjected to external pressure resulting in overtravel, the product features a rigid “bottom‑dead‑center” limit at its base. This mechanism forcibly prevents the contact spring from exceeding its yield point due to excessive pressing, thereby completely eliminating the risk of elastic failure—namely, permanent plastic deformation.

II. Features and Advantages

(1) Ultra-long mechanical insertion/extraction lifespan

After undergoing rigorous fatigue strength testing, the product boasts up to 20,000 cycles (20,000 Cycles) Its exceptional durability far exceeds industry‑standard benchmarks, perfectly meeting the demands of devices such as TWS earbuds that undergo frequent charging and discharging.

(II) Flagship-Level Surface Treatment Technology

Contact Area: It features a high‑grade, full gold (Au) plating layer with a thickness of 30 µin, delivering unparalleled resistance to wear, oxidation, and chemical corrosion. On the critical inner shell (Shell 1), KRCONN has carefully selected materials that are resistant to acids and alkalis,

Its pitting resistance far exceeds that of ordinary stainless steel. SUS316L medical-grade stainless steel, Ensuring that it remains rust-free and maintains its performance even in extremely harsh environments such as seawater, sweat, or chemical cleaning agents.

Soldering Zone: Features a 1 µin. gold flash (Au) plating, which significantly reduces solder joint contact resistance while ensuring outstanding solderability and robust board‑to‑PCB retention.

(3) Rigorously selected industrial-grade substrates

High-purity C5191 phosphor bronze is selected, with the substrate thickness precisely controlled at T = 0.12 ± 0.005 mm. Combined with advanced materials‑based heat‑treatment processes, the spring contacts maintain exceptionally excellent fatigue resistance and a stable elastic recovery curve even at micrometer‑scale thicknesses.

(4) Precise and stable mechanical properties

Through professional CAE finite-element simulation, this spring clip exhibits linear, controllable compression feedback along the X‑axis, Y‑axis, and the resultant force direction. At the standard compression height, the resultant force remains stable at approximately 0.282 N, ensuring reliable electrical contact while delivering a comfortable, smooth mechanical damping experience.

III. Target Market and Applications (This product, with its exceptionally high physical stack‑space utilization—featuring a buried‑pad and stepped‑soldering design, a solder‑area height of 2.00 mm, and a contact‑area protrusion of 1.30 mm—is ideally suited for the mid‑ to high‑end electronics hardware market, where space constraints are stringent and quality stability is paramount.)

(1) Wireless Audio Terminal: Internal power‑transfer contacts in TWS Bluetooth earphone charging cases, and charging docks for bone‑conduction headphones.

(2) Smart Wearable Devices: Magnetic or snap‑on charging docks for smart sports watches, smart wristbands, and smart rings.

(3) Personal Care, Health, and Consumer Electronics ： High-end electric toothbrush wireless charging dock, portable beauty device, and smart water flosser base contact points.

(4) Precision Handheld Instruments and Small Household Appliances: Contact points for portable measuring instruments, handheld wire locators, and the expansion base of a desktop smart multifunction gateway.

(5) In-vehicle Connectivity and Smart Hardware: Two-wheeled electric vehicle outdoor smart dashboard, waterproof central controller for shared bicycles, and outdoor waterproof security surveillance camera.

IV. Product Parameters, Specifications, and Production & Supply Information