Waterproof FPC module

Abstract

The utility model discloses a waterproof FPC (Flexible Printed Circuit) module, which comprises a flexible circuit board, a connector, conductive adhesive and a reinforcing sheet, and is characterized in that the flexible circuit board is provided with a first surface and a second surface which are opposite to each other; the connector is arranged on the first surface of the flexible circuit board, and the reinforcing sheet is pasted and fixed on the second surface of the flexible circuit board through the conductive adhesive and corresponds to the connector; the FPC module further comprises a waterproof coating, and the waterproof coating is coated on the peripheral side surfaces of the conductive adhesive and the reinforcing sheet and the second surface of the flexible circuit board. The FPC module can prevent external water vapor from invading the conductive adhesive.

Description

Technical Field

[0001] The utility model relates to a flexible circuit board technology, in particular to an FPC module. Background Art

[0002] Flexible circuit board, also known as flexible printed circuit board or FPC for short, is a special printed circuit board. It is made of flexible insulating substrate and has many advantages that rigid printed circuit boards do not have. Its main features include excellent electrical performance, high reliability, excellent flexibility and high wiring density. This feature allows flexible circuit boards to be arranged arbitrarily according to spatial layout requirements and to move and stretch arbitrarily in three-dimensional space, thereby achieving the integration of component assembly and wire connection.

[0003] Usually, the flexible circuit board of a mobile phone display module will be equipped with a reinforcing steel sheet in the local area where the connector is mounted, and in order to avoid static electricity damaging the connector, the reinforcing steel sheet on the back of the connector will be grounded. At present, the grounding treatment of the reinforcing steel sheet is mainly to short-circuit the reinforcing steel sheet and the flexible circuit board through conductive glue, and to perform grounding through the grounding PIN pin on the flexible circuit board. For example, a Chinese patent with patent number 202320863464.X discloses an FPC structure, including: an FPC, a connector and a reinforcing steel sheet, the reinforcing steel sheet is attached to the front of the FPC with conductive glue, the connector is arranged on the back of the FPC, and at least two notches are arranged at the edge of the reinforcing steel sheet.

[0004] However, the sides of the conductive adhesive and the reinforcing steel sheet are directly exposed, and external water vapor can easily invade the junction between the conductive adhesive and the reinforcing steel sheet, as well as the junction between the conductive adhesive and the flexible circuit board. The base material of the conductive adhesive is a loose and porous resin matrix, which has strong water absorption. The invasion of external water vapor will cause the resistance of the conductive adhesive to increase, resulting in failure of grounding of the reinforcing steel sheet, and the inability to effectively conduct static electricity at the connector, which can easily cause static electricity damage; at the same time, it will also reduce the viscosity of the conductive adhesive, resulting in insufficient viscosity of the conductive adhesive, uneven or insufficient pressing pressure, and other problems. Utility Model Content

[0005] In order to solve the above-mentioned deficiencies of the prior art, the utility model provides an FPC module, which can prevent external water vapor from invading the conductive adhesive.

[0006] The technical problem to be solved by the utility model is achieved through the following technical solutions:

[0007] A waterproof FPC module comprises a flexible circuit board, a connector, a conductive adhesive and a reinforcing sheet, wherein the flexible circuit board has a first surface and a second surface opposite to each other; the connector is arranged on the first surface of the flexible circuit board, and the reinforcing sheet is fixed on the second surface of the flexible circuit board by the conductive adhesive and corresponds to the connector; the FPC module also comprises a waterproof coating, which is coated on the outer side surfaces of the conductive adhesive and the reinforcing sheet and on the second surface of the flexible circuit board.

[0008] Furthermore, the waterproof coating is also coated on a surface of the reinforcing sheet facing away from the circuit board.

[0009] Furthermore, the reinforcing sheet is a reinforcing metal sheet.

[0010] Furthermore, the reinforcing sheet is a reinforcing steel sheet.

[0011] Furthermore, the conductive adhesive includes a loose and porous resin matrix and a conductive filler filled in the resin matrix.

[0012] Furthermore, the resin matrix is ​​epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane or acrylic resin.

[0013] Furthermore, the conductive filler is metal powder, carbon black, graphite or conductive polymer.

[0014] Furthermore, the waterproof coating is a solder resist or a nano waterproof coating.

[0015] Furthermore, a grounding window is provided on the second surface of the flexible circuit board and grounding exposed copper is provided in the grounding window, a first opening is provided on the reinforcement sheet and is located in the grounding window, and a second opening corresponding to the first opening is provided on the conductive adhesive; the first opening and the second opening are filled with conductive material to electrically connect the reinforcement sheet with the grounding exposed copper in the grounding window.

[0016] Furthermore, the conductive material is silver paste or solder paste.

[0017] The utility model has the following beneficial effects: the FPC module of the utility model is coated with the waterproof coating on the outer side of the conductive glue and the reinforcing sheet and the second surface of the flexible circuit board, and the outer side of the conductive glue, the junction between the conductive glue and the reinforcing sheet, and the junction between the conductive glue and the flexible circuit board are sealed by the waterproof coating, so as to prevent external water vapor from invading the conductive glue from the outer side of the conductive glue, the junction between the conductive glue and the reinforcing sheet, and the junction between the conductive glue and the flexible circuit board, and prevent the resistance of the conductive glue from increasing due to the intrusion of water vapor, thereby ensuring the grounding effect of the reinforcing steel sheet and the static electricity conduction effect at the connector. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a planar structural diagram of the FPC module provided by the utility model.

[0019] Figure 2 for Figure 1 AA cross-sectional view of the FPC module shown.

[0020] Figure 3 for Figure 2 An enlarged view of point B in the FPC module is shown.

[0021] Figure 4 This is a partially enlarged cross-sectional view of another FPC module provided by the utility model.

[0022] Figure 5 This is a planar structural diagram of another FPC module provided by the utility model.

[0023] Figure 6 for Figure 5 The CC cross-sectional view of the FPC module shown.

[0024] Figure 7 for Figure 6 An enlarged view of point D in the FPC module shown. Implementation

[0025] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Embodiment 1

[0029] like Figure 1-3 As shown, a waterproof FPC module includes a flexible circuit board 1, a connector 2, a conductive adhesive 3 and a reinforcing sheet 4, wherein the flexible circuit board 1 has a first surface and a second surface opposite to each other; the connector 2 is arranged on the first surface of the flexible circuit board 1, and the reinforcing sheet 4 is fixed to the second surface of the flexible circuit board 1 by pasting the conductive adhesive 3 and corresponding to the connector 2; the FPC module also includes a waterproof coating 5, which is coated on the outer side surfaces of the conductive adhesive 3 and the reinforcing sheet 4 and the second surface of the flexible circuit board 1.

[0030] The FPC module of the utility model is coated with the waterproof coating 5 on the outer side of the conductive glue 3 and the reinforcing sheet 4 and the second surface of the flexible circuit board 1, and the outer side of the conductive glue 3, the junction between the conductive glue 3 and the reinforcing sheet 4, and the junction between the conductive glue 3 and the flexible circuit board 1 are sealed by the waterproof coating 5, so as to prevent external water vapor from invading the conductive glue 3 from the outer side of the conductive glue 3, the junction between the conductive glue 3 and the reinforcing sheet 4, and the junction between the conductive glue 3 and the flexible circuit board 1, and prevent the resistance of the conductive glue 3 from increasing due to the intrusion of water vapor, thereby ensuring the grounding effect of the reinforcing steel sheet and the static electricity conduction effect at the connector 2.

[0031] The waterproof coating 5 may be, but is not limited to, a solder resist or a nano waterproof coating.

[0032] The solder resist is an acrylic oligomer having the characteristics of being waterproof, rust-proof, corrosion-resistant, and resistant to high and low temperatures. It is a commonly used protective coating for printed circuit boards and is generally applied to circuits and substrates on printed circuit boards that do not require soldering to protect the circuits and substrates.

[0033] The nano waterproof coating is a waterproof material that combines nano-level waterproof materials with other substances using nanotechnology. Its waterproof performance is better than that of traditional waterproof materials. It has extremely high water resistance and moisture resistance, and can effectively prevent water penetration and erosion. The main ingredients of common nano waterproof coatings include nano SiO2, nano TiO2, polyvinyl acetate emulsion, potassium silicate, lithium silicate, potassium titanate whisker, water-based self-drying silicone modified acrylic resin HA8840, nano carbon powder, nano zinc oxide, oxidized starch, urea, actinolite powder, ethylene glycol dimethacrylate, bonding aid, deionized water, etc.

[0034] The conductive adhesive 3 includes a loose and porous resin matrix and a conductive filler filled in the resin matrix. The resin matrix plays a role of bonding and fixing in the conductive adhesive 3, while the conductive filler gives the conductive adhesive 3 conductive properties. After curing, the resin matrix will form a loose and porous three-dimensional skeleton structure to provide sufficient filling space for the conductive filler. However, the loose and porous structure of the resin matrix also leads to good water absorption, which is easily invaded by external water vapor and causes the resistance value to increase, thereby affecting the grounding effect and static discharge effect of the reinforcing sheet 4.

[0035] Specifically, the resin matrix may be, but is not limited to, epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane or acrylic resin, and the conductive filler may be, but is not limited to, metal powder, carbon black, graphite or conductive polymer.

[0036] In this embodiment, the reinforcing sheet 4 is a reinforcing metal sheet, and preferably, the reinforcing sheet 4 is a reinforcing steel sheet. Embodiment 2

[0037] As an optimization solution of the first embodiment, in this embodiment, if Figure 4 As shown, the waterproof coating 5 is also coated on the surface of the reinforcing sheet 4 facing away from the circuit board, so as to seal the conductive adhesive 3 and the reinforcing sheet 4 as a whole on the flexible circuit board 1, thereby maximizing the ability to prevent water vapor intrusion. Embodiment 3

[0038] As an optimization solution of Embodiment 1 or Embodiment 2, in this embodiment, if Figure 5-7 As shown, a grounding window 11 is provided on the second surface of the flexible circuit board 1 and grounding exposed copper is provided in the grounding window 11, a first opening located in the grounding window 11 is provided on the reinforcing sheet 4, and a second opening corresponding to the first opening is provided on the conductive adhesive 3; the first opening and the second opening are filled with conductive material 6 to electrically connect the reinforcing sheet 4 with the grounding exposed copper in the grounding window 11.

[0039] The FPC module of the present invention electrically connects the reinforcing sheet 4 to the grounding exposed copper in the grounding window 11 of the flexible circuit board 1 through the conductive material 6 in the first opening and the second opening, and the grounding exposed copper is connected to the copper foil routing inside the flexible circuit board 1, and grounding treatment is performed through the grounding routing and grounding PIN pin formed by the copper foil routing to conduct static electricity.

[0040] The grounding window 11 is formed by partially cutting and removing the insulating protective film on the surface of the flexible circuit board 1. Preferably, in order to avoid excessive copper exposure in the grounding window 11, the grounding window 11 is in the shape of a circular hole, and its size is adapted to the first opening and the second opening.

[0041] The conductive material 6 may be, but is not limited to, silver paste or solder paste.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the utility model rather than to limit them. Although the embodiments of the utility model are described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the embodiments of the utility model can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the utility model.

Claims

1. A waterproof FPC module, comprising a flexible circuit board, a connector, a conductive adhesive and a reinforcing sheet, wherein the flexible circuit board has a first surface and a second surface opposite to each other; the connector is arranged on the first surface of the flexible circuit board, and the reinforcing sheet is fixed on the second surface of the flexible circuit board by the conductive adhesive and corresponds to the connector; characterized in that: The FPC module also includes a waterproof coating, which is coated on the outer peripheral sides of the conductive adhesive and the reinforcing sheet and the second surface of the flexible circuit board.

2. The FPC module according to claim 1, characterized in that: The waterproof coating is also coated on a surface of the reinforcing sheet facing away from the circuit board.

3. The FPC module according to claim 1, characterized in that: The reinforcing sheet is a reinforcing metal sheet.

4. The FPC module according to claim 3, characterized in that: The reinforcing sheet is a reinforcing steel sheet.

5. The FPC module according to claim 1, characterized in that: The conductive adhesive comprises a loose and porous resin matrix and a conductive filler filled in the resin matrix.

6. The FPC module according to claim 5, characterized in that: The resin matrix is ​​epoxy resin, silicone resin, polyimide resin, phenolic resin, polyurethane or acrylic resin.

7. The FPC module according to claim 5, characterized in that: The conductive filler is metal powder, carbon black, graphite or conductive polymer.

8. The FPC module according to claim 1, characterized in that: The waterproof coating is a solder resist or a nano waterproof coating.

9. The FPC module according to claim 1, characterized in that: A grounding window is provided on the second surface of the flexible circuit board and grounding exposed copper is provided in the grounding window, a first opening located in the grounding window is provided on the reinforcement sheet, and a second opening corresponding to the first opening is provided on the conductive adhesive; the first opening and the second opening are filled with conductive material to electrically connect the reinforcement sheet with the grounding exposed copper in the grounding window.

10. The FPC module according to claim 9, characterized in that: The conductive material is silver paste or solder paste.

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