EP3085214A1

EP3085214A1 - Method for assembling an electromagnetic interference shield to a printed circuit board

Info

Publication number: EP3085214A1
Application number: EP13811978.9A
Authority: EP
Inventors: Emrah Mustafa HOSCOSKUN
Original assignee: Arcelik AS
Current assignee: Arcelik AS
Priority date: 2013-12-20
Filing date: 2013-12-20
Publication date: 2016-10-26
Also published as: WO2015090470A1

Abstract

The present invention relates a method for soldering a shield (2) to a PCB (1), the method of soldering comprising the steps of, inserting four shield pins (3) into a PCB (1), providing the PCB (1) with solder, cutting a planar sheet's four corners to obtain a flat sheet with removed square cut-outs at the corners and forming four side extensions (5) by bending four edges of the flat part (4) in one direction such that the flat part (4) is surrounded by substantially right-angled side extensions (5) in the form of a shield (2).

Description

METHOD FOR ASSEMBLING AN ELECTROMAGNETIC INTERFERENCE SHIELD TO A PRINTED CIRCUIT BOARD

The present invention relates to a method for assembling an electromagnetic interference (EMI) shield to a printed circuit board (PCB) prior to the wave soldering process.
Wave soldering is a soldering process by which electronic components are soldered much faster than manual soldering. An electronic assembly is accordingly obtainable by way of applying molten solder to a printed circuit board in a tank. Typically, after the electronic components are inserted into the PCB, the latter is passed across a wave of solder, in response to which the exposed metallic areas that are not protected with a coating (mask) become wet such that a mechanical and electrical connection is established.
Since electrical components and circuits are prone to electromagnetic interference (EMI) and radio frequency interference (RFI) caused by external sources or internal sources within the electronic equipment, electromagnetic interference is addressed by way of using EMI shielding to ensure proper operation of the equipment. In this regard, electronic circuits or components of a printed circuit board are typically shielded with shields that are soldered or otherwise affixed to the PCB.
Among others, one of the prior art disclosures in the technical field of the present invention can be referred to as WO2009105379 A1, which defines a shielding apparatus on a substrate, comprising a first wall having laterally spaced-apart detent protrusions, a second wall having an edge portion disposed relative to the first wall such that an interface between the edge portion of the second wall and the first wall is substantially sealed against the ingress and/or egress of electromagnetic interference.
The present invention, on the other hand, provides a method for soldering a shield to a PCB by which only the shield pins are soldered first and the shield is subsequently mountable in a more practical manner and in most cases, without requiring an operator. This substantially eliminates problems associated with the manufacturing cycle efficiency that would persist if the shield were to be manually soldered by an operator.
The present invention therefore provides a method for soldering a shield to a PCB subsequent to a soldering process as defined in Claim 1. The invention further provides an EMI shield as defined in Claim 3.
Primary object of the present invention is to provide a soldering process by which a protective shield is fixable on a PCB subsequent to the soldering process.
The present invention proposes a method for soldering a shield to a PCB in which four shield pins are placed into a PCB and the same is provided with solder, preferably by wave soldering. To obtain a shield to be connectible with the four pins after the soldering process is completed, a planar sheet’s four corners are cut and square cut-outs are removed at the corners. Four edges are then bent to obtain a one-side open box-like form. Two planar integrally connected retaining surfaces of a shield pin face and press against inner surfaces of two neighbouring side extensions at a corner of the shield. Said retaining surfaces are separated by a substantially right-angled folding line and coincides with an open line in between two adjacent lateral edges of two neighbouring side extensions.
Accompanying drawings are given solely for the purpose of exemplifying an EMI shield employed according to the method of the present invention, whose advantages over prior art were outlined above and will be explained in brief hereinafter.
The drawings are not meant to delimit the scope of protection as identified in the claims nor should they be referred to alone in an effort to interpret the scope identified in said claims without recourse to the technical disclosure in the description of the present invention.
Fig. 1 demonstrates a general perspective view of the components of the shield together with the PCB in an unassembled manner according to the present invention.
Fig. 2 demonstrates a general perspective view of the components of the shield together with the PCB in an assembled manner according to the present invention.
Fig. 3a and 3b respectively demonstrate inner and outer perspective views of the shield pin according to the present invention.
The following numerals are used in the present description:

PCB
Shield
Shield pin
Flat part
Side extensions
Lateral edge
Through-hole joint
Retaining surface
Folding line
Stem
Connection end

Electronic components of a PCB (1) are shielded against electro-magnetic radiation by means of a shielding as a conductive shield body fixed to the PCB (1) so as to cover these electronic components. The present invention proposes a method for soldering a shield (1) in the form of a metal body having a flat part (4) and four downwardly extending side extensions (5). The side extensions (5) are typically formed by conventional cutting tools such that a planar sheet’s four corners are cut out to obtain a sheet with removed square cut-outs at the corners. The side extensions (5) are then bent in one direction such that the flat part (4) is enclosed by substantially right-angled side extensions (5). The resulting structure is placed on the PCB (1) so as to be covering electronic components within the region defined by the flat part (4) and the four side extensions (5). It is to be noted that while all the side extensions (5) of the shield (2) are bent in a first direction, a given side extension (5) is not attached to any of the two neighbouring side extensions (5) so that although a lateral edge (6) of a first side extension (5) is substantially aligned with an adjacent lateral edge (6) of the neighbouring second side extension (5), the two lateral edges (6) are not fixed to each other. This provides that the shield’s (2) final position can be fine-tuned in terms of its mechanical engageability with the PCB (1) subsequent to the soldering process, as will be explained hereinafter. In a nutshell, the present invention proposes a method for soldering a shield (2) to a PCB (1), the method of soldering comprising the steps of a) inserting four shield pins (3) into a PCB (1), b) providing the PCB (1) with solder, c) cutting a planar rectangular sheet’s four corners to obtain a flat sheet with removed square cut-outs at the corners, d) forming four side extensions (5) by bending four edges of the flat part (4) in one direction such that the flat part (4) is surrounded by substantially right-angled side extensions (5) in the form of a shield (2) and e) attaching said shield (2) to said PCB (1) by the four shield pins (3) after the termination of the soldering process.
According to an embodiment of the invention, said step of attaching said shield (2) to the PCB (1) at the four shield pins (3) after the termination of the soldering process further comprises the step of fixing the shield (2) such that two planar integrally connected retaining surfaces (8) of a shield pin (3) confront and lean against the inner surfaces of two neighbouring side extensions (5) at a given corner of the shield (2).
As described above, the method of the invention provides that the four shield pins (3) are inserted into a PCB (1) and the PCB (1) is then provided with solder. To this end, the shield (2) is fixed to the PCB (1) at the four shield pins (3) only after the soldering process has taken place. The soldering process can preferably be performed by way of wave soldering by which all electronic components according to the required PCB layout, including the shield pins (3) are placed in the PCB (1) and accordingly soldered. In this process, a certain amount of molten solder flows downwards into intimate contact with the desired areas of the PCB (1), including the through-hole joints (7) into which the shield pins (3) are inserted. In a nutshell, the present invention proposes a PCB (1) having a conductive electro-magnetic radiation shield (2) fixable to the PCB (1) to cover electronic components of the same, the shield (2) being fixable by means of four shield pins (3) insertable into the PCB (1), the shield (2) having a flat part (4) and four side extensions (5) formed by removing four square cut-outs at the corners of the flat part (4) and bending four edges of the flat part (4) in one direction such that the flat part (4) is enclosed by substantially right-angled side extensions (5).
In a further embodiment of the invention, the shield pins (3) are structured to have two planar integrally connected retaining surfaces (8) separated by a folding line (9) such that said two retaining surfaces (8) have a retaining surface contact with the inner surfaces of two neighbouring side extensions (5) at a corner of the shield (2), where the folding line (9) coincides with an open line in between two adjacent lateral edges (6) of two neighbouring side extension (5).
The structure of the shield pins (3) according to the invention are shaped such that they have an enhanced surface contact with the side extensions (5) of the shield (2) so as to retain the same in a reliable manner. The shield pins (3) are structured to have two planar integrally connected retaining surfaces (8) separated by a folding line (9). When the shield (2) is assembled, the two retaining surfaces (8) lean against the inner surfaces of two neighbouring side extensions (5) at a given corner of the shield (2). It is to be noted that the soldering process may cause a certain amount of deformation in the structure of the shield pins (3). To this end, since the two adjacent lateral edges (6) of two neighbouring side extensions (5) are not attached to each other, this advantageously offers a certain amount of flexibility when assembling the shield (2).
In a further embodiment of the invention, the shield pins (3) have a stem (10) and a connection end (11), the connection end (11) having a reduced longitudinal cross-section compared to the stem (10) portion’s longitudinal cross-section, providing that the molten solder fill around the connection ends (11) of the shield pins (3) inserted into through-hole joints (7) in the PCB (1).
The invention therefore provides that a shield (2) is soldered to a PCB (1) by which the shield pins (3) are soldered first and the shield (2) is subsequently mountable in a more practical manner without requiring an operator. This enhances the manufacturing cycle efficiency since no manual soldering operation is effectable.

Claims

A method for soldering a shield (2) to a PCB (1), the method of soldering is characterized in that it comprises the steps of:

- inserting four shield pins (3) into a PCB (1),

- providing the PCB (1) with solder,

- cutting a planar rectangular sheet’s four corners to obtain a flat sheet with removed square cut-outs at the corners,

- forming four side extensions (5) by bending four edges of the flat part (4) in one direction such that the flat part (4) is surrounded by substantially right-angled side extensions (5) in the form of a shield (2) and

- attaching said shield (2) to said PCB (1) by the four shield pins (3) after the termination of the soldering process.
A method for soldering a shield (2) to a PCB (1) as in Claim 1, characterized in that said step of attaching the shield (2) to the PCB (1) by the four shield pins (3) after the termination of the soldering process further comprises the step of fixing the shield (2) such that two planar integrally connected retaining surfaces (8) of a shield pin (3) confront and lean against inner surfaces of two neighbouring side extensions (5) at a corner of the shield (2).
A PCB (1) having a conductive electro-magnetic radiation shield (2) fixable to the PCB (1) to cover electronic components of the same, characterized in that the shield (2) is fixable by means of four shield pins (3) insertable into the PCB (1), the shield (2) having a flat part (4) and four side extensions (5) formed by removing four square cut-outs at the corners of the flat part (4) and bending four edges of the flat part (4) in one direction such that the flat part (4) is enclosed by substantially right-angled side extensions (5).
A PCB (1) having a conductive electro-magnetic radiation shield (2) as in Claim 3, characterized in that the shield (2) is attachable to the PCB (1) by the four shield pins (3) after the termination of the soldering process.
A PCB (1) having a conductive electro-magnetic radiation shield (2) as in Claim 3 or 4, characterized in that the shield pins (3) are structured to have two planar integrally connected retaining surfaces (8) separated by a folding line (9).
A PCB (1) having a conductive electro-magnetic radiation shield (2) as in Claim 5, characterized in that said two retaining surfaces (8) have a retaining surface contact with inner surfaces of two neighbouring side extensions (5) at a corner of the shield (2).
A PCB (1) having a conductive electro-magnetic radiation shield (2) as in Claim 5 or 6, characterized in that the folding line (9) coincides with an open line in between two adjacent lateral edges (6) of two neighbouring side extensions (5).
A PCB (1) having a conductive electro-magnetic radiation shield (2) as in Claim 5, characterized in that the shield pins (3) have a stem (10) and a connection end (11), the connection end (11) having a reduced longitudinal cross-section compared to the stem (10).