Crimping terminal and crimping method thereof

Abstract

The invention discloses a crimping terminal and a crimping method thereof. The crimping terminal and the crimping method are used for stacked solderless connection of a flexible printed circuit board or a flexible flat cable. The crimping terminal comprises a terminal body with an accommodating groove, a first supporting boss and a second supporting boss which are alternately arranged and have different heights are arranged at the bottom of the groove, and crimping wings corresponding to the second supporting boss are arranged on the two sides of the groove. During crimping, the higher first support bosses guide the crimping wings to crimp towards the lower second support bosses in an oriented manner, and the FPC / FFC arranged between the crimping wings is pressed, so that mechanical interlocking and reliable electric connection are formed. The terminal is compact in structure and small in occupied space after being crimped; through the design of the U-shaped groove and the crimping wing with the sharp corner, the connector can adapt to conductors with different widths, realizes welding-free, high-reliability, low-cost and convenient-to-mount connection, and is especially suitable for automotive electronics and compact equipment.

Description

Technical Field

[0001] This application relates to the field of flexible printed circuit board or flexible flat cable connection, and particularly to a crimp terminal and crimping method thereof. Background Technology

[0002] Flexible printed circuit boards (FPCs) and flexible flat cables (FFCs) are widely used in electrical signal interconnection within consumer electronics, automotive electronics, and various precision equipment due to their advantages such as flexibility, small size, and light weight. In these applications, achieving reliable, efficient, and low-cost electrical connections between FPCs, between FFCs, or between FPCs and FFCs is a critical aspect affecting overall product performance and assembly processes.

[0003] Currently, the industry mainly uses two connection methods. The first is welding, such as connecting the conductors of FPC / FFC to the corresponding pads through thermocompression welding or manual welding. However, the welding process has inherent defects: firstly, the high temperature generated during welding can easily cause thermal damage to the flexible substrate of FPC / FFC, affecting its mechanical properties and long-term reliability; secondly, there is a risk of incomplete soldering or desoldering, and the connection reliability is insufficient under harsh environments such as vibration and impact.

[0004] The second mainstream method is crimping followed by mating. Specifically, the conductive cable or the conductor of the FPC / FFC is first crimped onto individual terminals, and then the male and female connectors with terminals are mated together. This usually requires an additional connector housing to provide retention force. While this approach avoids the high temperatures of soldering, its system structure is complex, with numerous components (including crimp terminals, mating terminals, and connector housings), resulting in a large overall footprint and hindering miniaturization and high-density integration. Furthermore, its assembly process is cumbersome, requiring multiple crimping and assembly steps, increasing production costs and assembly time. Summary of the Invention

[0005] The purpose of this application is to provide a crimp terminal and its crimping method that ensures high reliability of connection while also being simple in structure, small in space, easy to assemble and low in cost.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A crimp terminal for crimping stacked flexible printed circuit boards or flexible flat cables, comprising: a terminal body having a receiving groove for accommodating the flexible printed circuit board or flexible flat cable; a plurality of first support bosses and a plurality of second support bosses arranged alternately along the length of the receiving groove at the bottom thereof, wherein the height of the first support bosses is greater than the height of the second support bosses; a plurality of crimping wings located on both sides of the receiving groove, wherein the center of each crimping wing corresponds to the center of a second support boss; wherein, during the crimping process, the first support bosses are used to guide and restrict the curling trajectory of the crimping wings, causing the crimping wings to curl and press against the flexible printed circuit board or flexible flat cable at the second support bosses.

[0008] Furthermore, the terminal body has a U-shaped structure, and the receiving groove is a U-shaped groove.

[0009] Furthermore, the tip of the crimping wing has a pointed structure for piercing the insulation layer of the flexible printed circuit board or flexible flat cable.

[0010] Furthermore, the press-fit wing curls to form a B-shaped or Ω-shaped structure.

[0011] Furthermore, the first support boss and the second support boss are integrally stamped with the terminal body.

[0012] Furthermore, the outer surface of the press-fit wing is provided with a guide slope.

[0013] A crimping method for a crimp terminal includes the following steps: stacking and aligning at least two layers of flexible printed circuit board or flexible flat cable conductor areas; placing the stacked conductor areas above the U-shaped groove of the crimp terminal; determining the width of the conductor areas: if the width of the conductor areas is less than or equal to the width of the U-shaped groove, then placing them directly into the U-shaped groove; if the width of the conductor areas is greater than the width of the U-shaped groove, then covering the U-shaped groove with the conductor areas and aligning the tips of the crimping wings with the insulating layers on both sides of the conductor areas; pressing down the crimping wings with a crimping tool, causing them to curl towards the second supporting boss along the direction guided by the first supporting boss; during the curling process, the crimping wings pierce the insulating layer of the flexible printed circuit board or flexible flat cable and form an engagement structure with the second supporting boss, completing the crimp connection.

[0014] The beneficial effects of this application are as follows:

[0015] (1) Because the height of the first support boss in this application is greater than that of the second support boss, and they are alternately arranged along the length direction at the bottom of the receiving groove, this structure forms a natural guiding and limiting mechanism during the crimping process. When the crimping tool presses down on the crimping wing, the higher first support boss first contacts and guides the initial curling direction of the crimping wing, forcing it to bend directionally towards the area of ​​the lower second support boss. This controlled curling trajectory ensures that the crimping force is concentrated and precisely applied to the FPC / FFC conductor area above the second support boss. The crimping wing finally completes curling at the second support boss and forms a mechanical engagement. This process causes the conductor to undergo plastic deformation and form a multi-point, high-stress, tight contact between the crimping wing and the support boss. This avoids poor contact caused by uneven pressure distribution and establishes a connection point with high mechanical holding force and low contact resistance. Its vibration resistance and loosening resistance reliability far exceed those of traditional welding or non-guided crimping.

[0016] (2) This invention integrates the receiving groove, supporting boss, and crimping wing into a single terminal body, eliminating the need for separate terminals, connector housings, and other components in traditional solutions. The receiving groove provides initial lateral positioning for stacked FPCs / FFCs; the groove bottom structure formed by the high and low bosses provides initial longitudinal support and positioning for the conductors before crimping; and the crimping wing serves as the final fixing and electrical contact component. The total volume of the connection point is only slightly larger than the terminal body itself, minimizing space occupation, making it particularly suitable for high-density installations. At the same time, the assembly process is simplified to two steps: "placement-crimping," eliminating the need for welding, interlocking, or assembling multiple independent parts, significantly reducing operational complexity, working hours, and cumulative errors caused by assembling multiple parts.

[0017] (3) The center of each crimping wing in this application corresponds to the center of a second support boss. This array-like one-to-one correspondence allows a single crimping terminal to form multiple parallel crimping points that are mechanically and electrically independent. Even if a single crimping point experiences performance degradation under extreme conditions, other crimping points can still maintain circuit continuity, thus improving the overall connection reliability of the system (redundant design). At the same time, multiple parallel contact points share the operating current, reducing the current density and heat load of a single contact point, thereby improving the overall current carrying capacity and long-term operating stability of the terminal.

[0018] (4) The basic U-shaped structure of the receiving groove in this application provides the main receiving space for the conductor. When the conductor width is less than or equal to the groove width, it can be fully embedded, with lateral protection provided by the groove wall. When the conductor width is greater than the groove width, its two sides will overlap on the groove wall. At this time, the curling process of the crimping wing will directly apply pressure to this part of the area and puncture the insulation layer (if the crimping wing is designed with a pointed tip). Based on this adaptive principle of "embedding" or "overlapping" determined by the physical structure, it can be seen that the same terminal structure can adapt to FPC / FFC of different widths within a certain range without modification, which improves the versatility of parts and the efficiency of inventory management, and reduces the need to design and manufacture multiple specifications of terminals to adapt to different products. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a flexible printed circuit board and a crimp terminal before crimping, according to an embodiment of this application.

[0020] Figure 2 This is a three-dimensional structural diagram of the crimp terminal before crimping according to an embodiment of this application;

[0021] Figure 3 This is a side view of a crimp terminal provided in an embodiment of this application before crimping;

[0022] Figure 4 This is a front view of a flexible printed circuit board and a crimp terminal provided in an embodiment of this application before crimping;

[0023] Figure 5 This is a top view of a flexible printed circuit board and a crimp terminal provided in an embodiment of this application after crimping;

[0024] Figure 6 A structural view provided in an embodiment of this application, showing that when the width of the flexible printed circuit board is greater than the width of the U-shaped groove of the crimp terminal, the sharp corner can reliably pierce the insulating layers on both sides;

[0025] Figure 7 This is a schematic diagram of the structure of a flexible printed circuit board and a crimping terminal provided in an embodiment of this application after crimping;

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Terminal body; 2. Receiving groove; 3. First support boss; 4. Second support boss; 5. Crimping wing; 51. Sharp corner structure; 52. Guide slope; Detailed Implementation

[0028] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.

[0029] like Figure 1 As shown, a crimp terminal is used to crimp stacked flexible printed circuit boards E or flexible flat cables. In this embodiment, the flexible printed circuit board E is used as an example, which includes a first flexible printed circuit board E1 and a second flexible printed circuit board E2.

[0030] like Figure 2 As shown, the crimp terminal includes: a terminal body 1 having a receiving groove 2 for accommodating a flexible printed circuit board or a flexible flat cable; a plurality of first support bosses 3 and a plurality of second support bosses 4 located at the bottom of the receiving groove 2 and arranged alternately along its length, wherein the height H1 of the first support bosses 3 is greater than the height H2 of the second support bosses 4; a plurality of crimping wings 5 ​​located on both sides of the receiving groove 2, wherein the center of each crimping wing 5 corresponds to the center of a second support boss 4; wherein, during the crimping process, the first support bosses 3 are used to guide and restrict the curling trajectory of the crimping wings 5, so that the crimping wings 5 ​​curl and press the flexible printed circuit board or flexible flat cable at the second support bosses 4.

[0031] like Figure 3 As shown, in one embodiment, the terminal body 1 has a U-shaped structure, and the receiving groove 2 is a U-shaped groove. The U-shaped structure gives the terminal body 1 a natural guiding and surrounding function, enabling it to more stably receive and initially position the stacked FPC / FFC, preventing conductor misalignment before crimping. This structure is simple and compact, easy to manufacture efficiently through continuous stamping processes, and effectively reduces production costs.

[0032] like Figure 4 As shown, in one embodiment, the tip of the crimping wing 5 has a pointed structure 51 for piercing the insulation layer of the flexible printed circuit board or flexible flat cable. The pointed structure 51 enables the terminal to have a "piercing" connection capability. When the conductor width is greater than the width of the U-shaped groove, the pointed corner can reliably pierce the insulation layers on both sides, ensuring direct contact between the metal crimping wing 5 and the conductor metal layer, thereby achieving a reliable electrical connection. This greatly improves the terminal's adaptability and versatility to different specifications of FPC / FFC.

[0033] like Figure 7 As shown, in one embodiment, the crimping wing 5 curls to form a B-shaped or Ω-shaped structure. The B-shaped or Ω-shaped curling form constitutes a nearly closed or completely closed mechanical locking ring. This structure can tightly bind the conductor around the support boss, providing uniform and durable radial clamping force, significantly enhancing the vibration resistance and loosening resistance of the connection point, and ensuring the mechanical and electrical reliability of long-term use.

[0034] like Figure 3As shown, in one embodiment, the first support boss 3 and the second support boss 4 are integrally stamped with the terminal body 1. This integral stamping process ensures that there is no connecting interface between the support boss and the terminal body 1, resulting in extremely high structural integrity and mechanical strength. This process is highly efficient, low-cost, and can precisely guarantee the consistency of the boss's size and position, thereby ensuring the stability and reliability of the performance of each crimping point.

[0035] like Figure 3 As shown, in one embodiment, the outer surface of the crimping wing 5 is provided with a guide slope 52. The guide slope 52 provides a smooth guiding effect during the initial pressing of the crimping tool, reduces the initial pressing force, and allows the crimping force to be more smoothly converted into the curling deformation of the crimping wing 5. This helps protect the crimping tool and the terminal itself, makes the crimping process smoother and more controllable, and facilitates automated crimping operations.

[0036] like Figures 1 to 7 As shown, a crimping method for a crimp terminal includes the following steps: stacking and aligning at least two layers of flexible printed circuit board or flexible flat cable conductor areas; placing the stacked conductor areas above the U-shaped groove of the crimp terminal; determining the width of the conductor area: if the width of the conductor area is less than or equal to the width of the U-shaped groove, then placing it directly into the U-shaped groove; if the width of the conductor area is greater than the width of the U-shaped groove, then covering the U-shaped groove with the conductor area and aligning the tip of the crimping wing 5 with the insulation layers on both sides of the conductor area; pressing down the crimping wing 5 with a crimping tool, causing it to curl towards the second support boss 4 along the direction guided by the first support boss 3; during the curling process, the crimping wing 5 punctures the insulation layer of the flexible printed circuit board or flexible flat cable and forms an engagement structure with the second support boss 4, completing the crimp connection.

[0037] The working principle of this application is as follows:

[0038] During operation, the stacked FPC / FFC conductor areas are placed on the U-shaped groove area. When external crimping force is applied to the top of the crimping wing 5 through a tool, the crimping wing 5 begins to bend into the groove. At this time, the higher first support boss 3 first contacts the side of the crimping wing 5, serving as an initial guide and lateral limit, forcing the bending deformation of the crimping wing 5 to be constrained within the space between the two first support bosses 3, and guiding it towards the area of ​​the lower second support boss 4. This guiding mechanism ensures that the curling trajectory of the crimping wing 5 is controllable and repeatable.

[0039] As the crimping wing 5 is guided above the second support boss 4 and continues to press down, the legs of the crimping wing 5 compress the conductor material, causing it to undergo plastic deformation and tightly wrap around the second support boss 4. Finally, the end of the crimping wing 5 curls up at or adjacent to the second support boss 4, typically forming a closed or nearly closed annular structure in the shape of a "B" or "Ω". The curled legs of the crimping wing 5 are mechanically connected or tightly fitted to the sides and top of the second support boss 4. The plastically deformed conductor material is squeezed and filled into the complex microstructure formed by the crimping wing 5 and the support boss, creating a mechanical interlock at both the macroscopic and microscopic levels. The array of multiple alternating support bosses and crimping wings 5 ​​ensures that the crimping force and holding force are evenly distributed along the conductor's length, avoiding stress concentration.

[0040] The embodiments described above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of this application, and these improvements and substitutions should also be considered within the scope of protection of this application.

Claims

1. A crimp terminal for crimping stacked flexible printed circuit boards or flexible flat cables, characterized in that, include: The terminal body has a receiving groove for accommodating the flexible printed circuit board or flexible flat cable; A plurality of first support bosses and a plurality of second support bosses are located at the bottom of the receiving groove and are alternately arranged along its length, wherein the height of the first support bosses is greater than the height of the second support bosses. Multiple crimping wings are located on both sides of the receiving groove, and the center of each crimping wing corresponds to the center of a second support boss; During the crimping process, the first support boss is used to guide and limit the curling trajectory of the crimping wing, so that the crimping wing curls and presses against the flexible printed circuit board or flexible flat cable at the second support boss.

2. A crimp terminal according to claim 1, characterized in that, The terminal body has a U-shaped structure, and the receiving groove is a U-shaped groove.

3. A crimp terminal according to claim 1, characterized in that, The crimping wing has a pointed tip for piercing the insulation layer of the flexible printed circuit board or flexible flat cable.

4. A crimp terminal according to claim 1, characterized in that, The press-fit wing curls to form a B-shaped or Ω-shaped structure.

5. A crimp terminal according to claim 1, characterized in that, The first support boss and the second support boss are integrally stamped with the terminal body.

6. A crimp terminal according to claim 1, characterized in that, The outer side of the press-fit wing is provided with a guide slope.

7. A crimping method using a crimp terminal as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Stack and align at least two layers of flexible printed circuit boards or flexible flat cable conductor areas; Place the stacked conductor area above the U-shaped groove of the crimp terminal; Determine the width of the conductor region: If the width of the conductor region is less than or equal to the width of the U-shaped groove, then it is directly placed into the U-shaped groove; If the width of the conductor area is greater than the width of the U-shaped groove, then the conductor area is covered on the U-shaped groove, and the tip of the crimping wing is aligned with the insulating layer on both sides of the conductor area; Press down the crimping wing with a crimping tool to make it curl toward the second support boss in the direction guided by the first support boss. During the crimping process, the crimping wing punctures the insulation layer of the flexible printed circuit board or flexible flat cable and forms an engagement structure with the second support boss to complete the crimping connection.

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