WO2018146369A1

WO2018146369A1 - A circuit board system and method for manufacturing the same

Info

Publication number: WO2018146369A1
Application number: PCT/FI2017/050066
Authority: WO
Inventors: Antti Holma; Ari TIKKANEN; Sauli KUNNAS
Original assignee: Coriant Oy
Priority date: 2017-02-07
Filing date: 2017-02-07
Publication date: 2018-08-16

Abstract

A circuit board system comprises a circuit board (101) comprising holes (102-104) and an electric component (105) on a first side of the circuit board. The electric component comprises press-fit connection pins (106-108) forming friction fits with the walls the holes of the circuit board. Each of the holes of the circuit board comprises a broadening (109) at the mouth of the hole on the first side of the circuit board. The broadenings of the holes facilitate insertion of the press-fit connection pins in the holes. Thus, the broadenings reduce a risk that one or more of the press-fit connection pins is bent and thereby incorrectly positioned during installation of the electric component on the circuit board.

Description

A circuit board system and method for manufacturing the same

Field of the disclosure

The disclosure relates to a circuit board system that comprises a circuit board and one or more electric components attached with press-fit connection pins to the circuit board. Furthermore, the disclosure relates to a method for manufacturing a circuit board system of the kind mentioned above.

Background

A typical circuit board system comprises a circuit board furnished with electric components. The circuit board comprises one or more layers of electrically insulating material and electrical conductors on one or both of the surfaces of the circuit board and/or between the layers of the electrically insulating material. Each of the electric components can be for example an integrated circuit such as a processor or a memory, or a discrete component such as a resistor, a capacitor, an inductor, a transistor, a diode, or an electric connector. In many cases, one or more of the electric components are press-fit components which comprise press-fit connection pins inserted in corresponding holes of the circuit board and forming friction fits with the walls of the holes of the circuit board.

An inherent challenge related to press-fit components of the kind mentioned above is a risk that one or more press-fit connection pins of a press-fit component are not properly inserted in corresponding holes of a circuit board but, instead, the one or more press-fit connection pins are bent and thereby incorrectly positioned during installation of the press-fit component on the circuit board. A press-fit connection pin is bent in cases where the tip of the press-fit connection pin is not appropriately aligned with the mouth of the respective hole when a press-fit component is pressed towards a circuit board. In conjunction with many circuit board systems, it may be difficult to check after installation of a press-fit component whether all press-fit connection pins have been properly inserted in the corresponding holes of a circuit board. Furthermore, especially in conjunction with press-fit mounted electric connectors, problems may arise a long time after a product, e.g. a telecommunication device, comprising one or more press-fit mounted electric connectors has been taken into use because functionalities using a press-fit connection which happens to be faulty may be needed not immediately after the product has been taken into use but a long time thereafter. Thus, a fault finding process can be arduous, expensive, and time consuming.

A typical approach to reduce the above-described risk of faulty press-fit connections is to provide each press-fit connection pin with an elongated tip portion which is thinner than the other portion of the press-fit connection pin and thereby the elongated tip portion is loose with respect to a corresponding hole of a circuit board. As the elongated tip portions are loose with respect to holes of a circuit board, a press-fit component can be installed in two phases so that the elongated tip portions are first inserted in the holes of the circuit board and thereafter the other portions of the press-fit connection pins are pushed in the holes using a sufficient pressing force. The elongated tip portions are advantageously so long that it is easy to notice if the elongated tip portion of a press-fit connection pin is not properly in a respective hole and thereby it is easy to avoid pressing a press-fit component towards a circuit board in cases where the pressing would bend one or more press-fit connection pins instead of providing desired friction fits. Press-fit connection pins having an elongated tip portion of the kind described above can be however unsuitable for transferring high frequency signals because a long press-fit connection pin may act as an antenna in an adverse way. In many high frequency applications, press-fit connection pins should be as short as possible. Summary

The following presents a simplified summary in order to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments of the invention.

In this document, the word "geometric" when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional.

In accordance with the invention, there is provided a new circuit board system that can be, for example but not necessarily, a part of a telecommunication device that can be for example an Internet Protocol "IP" router, a Multiprotocol Label Switching "MPLS" switch, a packet optical switch, an Ethernet switch, a software- defined networking "SDN" controlled network element, and/or a SDN-controller.

A circuit board system according to the invention comprises:

- a circuit board comprising holes each of which comprises a broadening at a mouth of the hole on a first side of the circuit board, and

- an electric component on the first side of the circuit board, the electric component comprising press-fit connection pins forming friction fits with the walls the holes of the circuit board.

The broadenings of the holes of the circuit board facilitate insertion of the press-fit connection pins in the holes. Thus, the broadenings of the holes reduce a risk that one or more of the press-fit connection pins is bent and thereby incorrectly positioned during installation of the electric component on the circuit board.

The above-mentioned broadenings are advantageously so wide that tip portions of the press-fit pins are loose with respect to the broadenings, and therefore the above-mentioned electric component can be installed in two phases so that the tip portions of the press-fit pins are first inserted in the broadenings and thereafter the press-fit connection pins are pushed in the other portions of the holes using a sufficient pressing force. The broadenings are advantageously so deep that it is easy to notice if the tip portion of a press-fit connection pin is not in a corresponding broadening and thereby it is easy to avoid pressing the above- mentioned electric component towards the circuit board in cases where the pressing would bend one or more press-fit connection pins instead of providing desired friction fits. As the broadenings of the holes provide the above-described advantages, there is no need to provide the press-fit connection pins with elongated tip portions and therefore a circuit board system according to the invention can be suitable for high frequency applications too.

In accordance with the invention, there is provided also new method for manufacturing a circuit board system according to the invention. A method according to the invention comprises:

- manufacturing a circuit board comprising holes each of which comprises a broadening at a mouth of the hole on a first side of the circuit board, and

- installing an electric component on the first side of the circuit board, the electric component comprising press-fit connection pins and being installed so that each of the press-fit connection pins is inserted in a corresponding one of the holes of the circuit board so as to form friction fits between the press-fit connection pins and the walls of the holes of the circuit board.

A number of exemplifying and non-limiting embodiments of the invention are described in accompanied dependent claims.

Various exemplifying and non-limiting embodiments of the invention both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and non-limiting embodiments when read in connection with the accompanying drawings.

The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

Brief description of the figures

Exemplifying and non-limiting embodiments of the invention and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figures 1 a, 1 b, 1 c, and 1 d illustrate a circuit board system according to an exemplifying and non-limiting embodiment of the invention, figure 2 illustrates a detail of a circuit board system according to another exemplifying and non-limiting embodiment of the invention, and figure 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for manufacturing a circuit board system according to an exemplifying and non-limiting embodiment of the invention.

Description of exemplifying and non-limiting embodiments The specific examples provided in the description below should not be construed as limiting the scope and/or the applicability of the accompanied claims. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

Figures 1 a and 1 b show schematic section views of details of a circuit board system according to an exemplifying and non-limiting embodiment of the invention. The section shown in figure 1 a is taken along a line A1 -A1 shown in figure 1 b. The section plane related to figure 1 a is parallel with the xz-plane of a coordinate system 199. The section shown in figure 1 b is taken along a line A2-A2 shown in figure 1 a. The section plane related to figure 1 b is parallel with the xy-plane of the coordinate system 199. The circuit board system comprises a circuit board 101 furnished with one or more electric components. Each electric component can be, for example, an integrated circuit such as a processor or a memory, or a discrete component such as a resistor, a capacitor, an inductor, a transistor, a diode, or an electric connector for electrically connecting the circuit board system to an external electric system. In figure 1 a, one of the electric components is denoted with a reference 105. The electric component 105 can be, for example but not necessarily, an electric connector. The circuit board 101 comprises layers of electrically insulating material and electric conductors between the layers of the electrically insulating material. In figure 1 a, one of the electric conductors of the circuit board 101 is denoted with a reference 1 1 1 . The circuit board system can be, for example but not necessarily, a part of a telecommunication device that can be for example an Internet Protocol "IP" router, a Multiprotocol Label Switching "MPLS" switch, a packet optical switch, an Ethernet switch, a software-defined networking "SDN" controlled network element, and/or a SDN-controller.

The circuit board 101 comprises holes, and the electric component 105 comprises press-fit connection pins which form friction fits with the walls the holes of the circuit board 101 . The number of the press-fit connection pins of the electric component 105 can be for example at least 10, at least 20, or at least 50. In figure 1 a, three of the holes of the circuit board 101 are denoted with references 102, 103, and 104, and three of the press-fit connection pins of electric component 105 are denoted with references 106, 107, and 108. As illustrated in figures 1 a and 1 b, each of the holes comprises a broadening at the mouth of the hole on the same side of the circuit board on which the electric component 105 is located. In figures 1 a and 1 b, the broadening of the hole 102 is denoted with a reference 109. The broadenings of the holes facilitate insertion of the press-fit connection pins in the holes.

In the exemplifying circuit board system illustrated in figures 1 a and 1 b, the broadenings of the holes have cylindrical shapes. In each hole, the diameter d1 of the broadening can be e.g. at least 10 % or at least 20 % greater than the diameter d2 of the portion of the hole forming the friction fit with the corresponding press-fit connection pin.

In the exemplifying circuit board system illustrated in figures 1 a and 1 b, the portion of each hole forming the friction fit with the corresponding press-fit connection pin is coated with electrically conductive material 1 10 and the broadening of the hole is free from an electrically conductive coating. In this exemplifying case, the broadenings can be made e.g. by drilling after the holes have been coated with the electrically conductive material. It is also possible that also the broadenings are coated with electrically conductive material. In this exemplifying case, the broadenings can be made e.g. by drilling and thereafter to the holes provided with the broadenings can be coated with the electrically conductive material.

Figure 1 c illustrates the above-described circuit board system in a situation where the electric component 105 is positioned with respect to the circuit board 101 to be ready for being pushed towards the circuit board 101 so that the press-fit connection pins of the electric component 105 are inserted in the holes of the circuit board. Figure 1 d illustrates the above-described circuit board system in another situation where the press-fit connection pin 108 is warped so that pushing the electric component 105 towards the circuit board 101 would lead to a situation in which the press-fit connection pin 108 is bent and incorrectly positioned with respect to the circuit board 101 . In the situation shown in figure 1 c, the distance H between the body portion of the electric component 105 and a surface of the circuit board 101 is H1 . In the situation shown in figure 1 d, the distance H is H2.

When the circuit board system is assembled, the above-mentioned distance H can be used for determining whether there is the situation shown in figure 1 c or a situation such as shown in figure 1 d. For example, a threshold value H_th can be set so that the situation shown in figure 1 c is deemed to be present when the distance H is less than the threshold value H_th and a situation such as shown in figure 1 d is deemed to be present when the distance H is greater than or equal to the threshold value H_th. For example, a press-fit assembly machine can be configured to check whether the distance H, or similar, is less than the threshold value H_th and to press the electric component towards the circuit board only if the distance H, or similar, is less than the threshold value H_th. As can be understood based on figures 1 c and 1 d, the difference between the distances H2 and H1 , i.e. H2 - H1 , is increased by the broadenings of the holes of the circuit board. If there were no broadenings of the kind described above, the difference between the distances H2 and H1 might be so small that it might be challenging to be able to determine whether the press-fit connection pins are correctly positioned with respect to the holes of the circuit board so that pressing the electric component towards the circuit board leads to a desired result.

Figure 2 shows a schematic section view of a detail of a circuit board system according to an exemplifying and non-limiting embodiment of the invention. The section plane is parallel with the xz-plane of a coordinate system 299. The circuit board system comprises a circuit board 201 comprising holes each of which comprises a broadening at a mouth of the hole on a first side of the circuit board. Figure 2 shows a section view of one of the holes of the circuit board. The hole is denoted with a reference 202, and the broadening of the hole 202 is denoted with a reference 209. The circuit board system comprises an electric component on the first side of the circuit board. The electric component comprises press-fit connection pins forming friction fits with the walls the holes of the circuit board. In figure 2, one of the press-fit connection pins is denoted with a reference 206. In this exemplifying circuit board system, the broadenings of the holes of the circuit board have a shape of a truncated cone.

In the exemplifying circuit board systems described above with reference to figures 1 a-1 d and to figure 2, the holes for the press-fit connections pins are through- holes. It is however also possible that one or more holes for press-fit connections pins are not through-holes Figure 3 shows a flowchart of a method according to an exemplifying and non- limiting embodiment of the invention for manufacturing a circuit board system according to an exemplifying embodiment of the invention. The method comprises the following actions:

- action 301 : manufacturing a circuit board comprising holes each of which comprises a broadening at a mouth of the hole on a first side of the circuit board, and

- action 302: installing an electric component on the first side of the circuit board, the electric component comprising press-fit connection pins and being installed so that each of the press-fit connection pins is inserted in a corresponding one of the holes of the circuit board so as to form friction fits between the press-fit connection pins and walls of the holes of the circuit board.

In a method according to an exemplifying and non-limiting embodiment of the invention, the broadenings of the holes of the circuit board are made by drilling. In a method according to an exemplifying and non-limiting embodiment of the invention, the broadenings of the holes of the circuit board are made by drilling after each of the holes is at least partially coated with electrically conductive material.

The specific examples provided in the description given above should not be construed as limiting the scope and/or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:

1 . A circuit board system comprising:

- a circuit board (101 , 201 ) comprising holes (102-104, 202), and

- an electric component (105) on a first side of the circuit board, the electric component comprising press-fit connection pins (106-108, 206) forming friction fits with walls the holes of the circuit board, characterized in that each of the holes of the circuit board comprises a broadening (109, 209) at a mouth of the hole on the first side of the circuit board, the broadening facilitating insertion of a corresponding one of the press-fit connection pins in the hole under consideration.

2. A circuit board system according to claim 1 , wherein a diameter (d1 ) of the hole at the mouth of the hole is at least 10 % greater than a diameter (d2) of a portion of the hole forming the friction fit with the press-fit connection pin.

3. A circuit board system according to claim 2, wherein the diameter (d1 ) of the hole at the mouth of the hole is at least 20 % greater than the diameter (d2) of the portion of the hole forming the friction fit with the press-fit connection pin.

4. A circuit board system according to any of claims 1 -3, wherein the broadening (109) has a cylindrical shape.

5. A circuit board system according to any of claims 1 -3, wherein the broadening (209) has a shape of a truncated cone.

6. A circuit board system according to any of claims 1 -5, wherein a portion of the hole forming the friction fit with the press-fit connection pin is coated with electrically conductive material (1 10) and the broadening of the hole is free from an electrically conductive coating.

7. A circuit board system according to any of claims 1 -6, wherein number of the press-fit connection pins of the electric component is at least ten.

8. A circuit board system according to any of claims 1 -7, wherein the electric component (105) is an electric connector for electrically connecting the circuit board system to an external electric system.

9. A method for manufacturing a circuit board system, the method comprising: - manufacturing (301 ) a circuit board comprising holes, and

- installing (302) an electric component on a first side of the circuit board, the electric component comprising press-fit connection pins and being installed so that each of the press-fit connection pins is inserted in a corresponding one of the holes of the circuit board so as to form friction fits between the press-fit connection pins and walls of the holes of the circuit board, characterized in that each of the holes of the circuit board comprises a broadening at a mouth of the hole on the first side of the circuit board in order to facilitate insertion of a corresponding one of the press-fit connection pins in the hole under consideration.

10. A method according to claim 9, wherein the broadening of each of the holes is made by drilling.

1 1 . A method according to claim 10, wherein the broadening of each of the holes is made by drilling after each of the holes is at least partially coated with electrically conductive material.