Printed circuit board (PCB) and method of manufacturing the same

Abstract

The invention relates to a printed circuit board (PCB) and a method of manufacturing it. The invention relates to a printed circuit board (1) for mechanical support and electrical connection of electrical or electronic components (2), having conductive tracks and contact pads (5) and a label (10), the conductive tracks and contact pads (5) being engraved or etched from at least one copper sheet layer (3) laminated onto a non-conductive substrate (4), and the label (10) being attached to the printed circuit board (1) at an intended position (11) prior to the assembly process. It has been found that soldering defects often occur due to an excess of solder paste (6) deposited on the contact pads (5) of the components (2) adjacent to the label (10). In order to prevent soldering defects due to an incorrect amount of solder paste application in a simple and inexpensive manner, the printed circuit board (1) provides the intended position (11) of the label (10) as a recess (12) relative to its surroundings.

Description

Technical Field

[0001] This invention relates to a printed circuit board for mechanical support and electrical connection of electrical or electronic components, wherein a label is attached to the printed circuit board prior to assembly processing. The invention also relates to a method for manufacturing such a PCB. Background Technology

[0002] Printed circuit boards (PCBs) provide mechanical support and electrical connections for electrical or electronic components. In PCB manufacturing, once the PCB dimensions are determined, the components specified in the circuit diagram and parts list are placed on the PCB, using conductive tracks, pads, and other features engraved or etched on and / or between one or more copper layers laminated to a non-conductive substrate to provide electrical connections for EMC, thermal, assembly rules, and other purposes.

[0003] Typically, a solder mask is applied at least to the conductive tracks to prevent oxidation and to prevent solder bridges from forming between closely spaced contact pads.

[0004] In surface mount technology (SMT), electronic components are mounted onto the surface of a printed circuit board (PCB) to connect the components. Components are typically soldered onto the PCB to electrically and mechanically secure them. Solder paste is deposited onto contact pads, usually through a reflow stencil. After the components are subsequently fitted onto the PCB at their designated contact pads, the assembly is subjected to controlled heating to reflow the solder paste in a molten state and form permanent solder joints.

[0005] Automated assembly, handling, testing, and packaging systems typically include automatic identification. Labels providing barcode or data matrix code information or any other data in a machine-readable form are usually attached to printed circuit boards prior to assembly processing to enable automatic identification and traceability.

[0006] It has been found that soldering defects frequently occur due to excessive solder paste deposition on the pads of adjacent components. Specifically, it has been discovered that excessive solder paste is added when the reflow stencil rises locally above the label level. In other words, a label rising too high from the printed circuit board causes the reflow stencil to rise locally. As a result, the printing process leads to incorrect solder paste volume deposition on the pads of adjacent components, ultimately resulting in soldering defects.

[0007] The extra space between the label and the surface mount component is unacceptable because reducing PCB size is a critical aspect. To provide more space for the label and offset the described soldering errors, a reflow stencil with recesses in the label area has been suggested. In the case of such a custom product, the reflow stencil would be very expensive. Summary of the Invention

[0008] The purpose of this invention is to prevent soldering defects caused by incorrect application of solder paste by a simple and inexpensive means.

[0009] This task is solved by a PCB having the features of the present invention. This task is also solved by a method for manufacturing such a PCB having the features of the present invention.

[0010] According to the present invention, the printed circuit board sets the intended position of the label in a recess relative to its surroundings. The recess prevents the reflow stencil from rising. Due to the recess, the reflow stencil is laid flat, which ensures the desired effect of solder paste printing.

[0011] The recess (or pocket) is made by the PCB manufacturer without any significant effort during standard processing. In a first embodiment of the invention, space is created for the label by setting the intended location of the label to a copper-free area.

[0012] According to a second aspect of the invention, at least the solder mask applied to the conductive track includes an opening region that overlaps with (and defines) the intended location of the label. Because the copper or solder mask is omitted, the printed circuit board has a recess at the designated location of the label.

[0013] In an advantageous embodiment of the invention, more space is provided for attaching tags, wherein the intended location of the tag is determined by providing both a copper-free area and a solder mask layer having an opening area that overlaps with the intended location of the tag.

[0014] In summary, the present invention provides a printed circuit board for mechanical support and electrical connection of electrical or electronic components, the printed circuit board having conductive tracks and contact pads, and a label, wherein the conductive tracks and contact pads are engraved or etched from at least one copper layer laminated to a non-conductive substrate, and the label is attached to the printed circuit board at a predetermined location prior to assembly processing.

[0015] The characteristic feature is that the printed circuit board sets the intended position of the label as a recess relative to its surroundings.

[0016] The intended location of the label is set as a copper-free area; the copper-free area at the intended location is formed by etching the copper layer, together with the formation of the conductive tracks and the contact pads; and the label directly abuts against the non-conductive substrate.

[0017] The recess is created by providing both a copper-free region at the intended location of the label and a solder mask layer having an opening region overlapping the intended location of the label, which is applied to at least the conductive track, such that the recess is formed at the intended location by being surrounded by the solder mask layer and the underlying copper sheet layer.

[0018] The present invention also provides a method for manufacturing a printed circuit board for mechanical support and electrical connection of electrical or electronic components, the method comprising the following steps:

[0019] - Lamination of at least one copper sheet layer onto a non-conductive substrate, and engraving or etching of conductive tracks and contact pads from the copper sheet layer.

[0020] - Attach the label to the printed circuit board at the intended location.

[0021] The characteristic feature is that the intended position of the label is manufactured as a recess relative to its surroundings.

[0022] The intended location of the label is set as a copper-free area; the copper-free area at the intended location is formed by etching the copper layer, together with the formation of the conductive tracks and the contact pads; and the label directly abuts against the non-conductive substrate.

[0023] The recess is created by providing both a copper-free region at the intended location of the label and a solder mask layer having an opening region overlapping the intended location of the label, which is applied to at least the conductive track, such that the recess is formed at the intended location by being surrounded by the solder mask layer and the underlying copper sheet layer. Attached Figure Description

[0024] These and other aspects of the invention will become apparent and elucidated by reference to the accompanying drawings in the embodiments described below, wherein:

[0025] Figures 1-3 A printed circuit board and its manufacturing method according to the prior art are described.

[0026] Figures 4-6 An embodiment of the printed circuit board according to the present invention and a method thereof are described.

[0027] In all the accompanying drawings, the same reference numerals are used for those elements of the PCB that have similar functions in the prior art and in embodiments according to the present invention. However, this does not necessarily mean that... Figure 4 , Figure 5 and Figure 6 The components represented in the middle are Figure 1 , Figure 2 and Figure 3 The elements indicated by corresponding reference numerals are the same. The differences are explained in each case to illustrate the invention. Detailed Implementation

[0028] Figures 1 to 3 and Figures 4 to 6Three key states in the assembly process of a printed circuit board (PCB) 1 using so-called surface mount technology are shown. PCB 1 is used to mechanically support and electrically connect electrical or electronic components 2. In surface mount technology, components have small metal tabs or end caps that can be directly soldered to the PCB surface, rather than wiring guides passing through holes.

[0029] Printed circuit boards are typically manufactured using copper as the conductive component, which is plated as one or more copper layers 3 onto a non-conductive substrate 4. The copper layer 3 is cut or etched according to the intended design of the PCB1 to expose the conductive tracks and contact pads 5 for the components 2.

[0030] To solder component 2, solder paste 6 is deposited onto contact pads 5 and typically printed using a reflow stencil 7. The reflow stencil 7 is flat and has through-holes 8 that allow the solder paste 6 to pass through and be deposited onto the PCB 1. The contact pads 5 printed with solder paste 6 are then mated with component 2.

[0031] Reference numeral 9 indicates a solder mask layer applied at least to the conductive track to prevent oxidation and to prevent solder bridges from forming between closely spaced contact pads 5.

[0032] Finally, the component is subjected to controlled heating to reflow the molten solder paste 6 and form permanent solder joints. In this process, the solder mask 9 is also baked and attached to the PCB1.

[0033] Attached to PCB1 is label 10, which provides barcode or data matrix code information or any other data in a visual, machine-readable form. Label 10 is applied to the surface of the PCB to ensure its legibility. Label 10 is placed in an area of ​​PCB1 where there is no component 2. Since there is no contact with pad 5 or engraved track in this intended location 11, it is placed according to... Figures 1 to 3 In the traditional arrangement, label 10 is placed on the solder mask layer 9 and the copper layer 3 below. Label 10 must have a certain thickness, especially because it must withstand the high temperatures during the soldering process and the chemicals used during the cleaning process.

[0034] Label 10 is thus raised to a level above its surroundings, so that the reflow stencil 7 rests on label 10 when the solder paste printed on PCB 1 is reflowed. In the normal procedure ( Figures 1 to 3 The reflow stencil 7 is pressed to a level exceeding that of the label 10, thereby creating a displaced cross-section of the perforation 8 of the stencil and free space in the perforation 8 area of ​​the reflow stencil 7, which results in an excess of solder paste 9 being applied to the contact pads 3.

[0035] According to the present invention, Figures 4 to 6The intended position 11 of the label is set in the printed circuit board 1 as a recess 12 relative to the surrounding area. This counteracts the undesirable lift of the reflow stencil 7 and prevents the application of excessive solder paste 6.

[0036] To create the desired recess 12, the intended location 11 of the label 10 is set as a copper-free area. The recess 12 (or pocket) is made by the PCB manufacturer during standard processing without any significant effort. In a first alternative, the copper-free area at the intended location 11 is formed by etching the copper layer 3 together with the formation of conductive tracks and contact pads 5.

[0037] In the second alternative, the recess 12 for receiving the label 10 is created by forming a solder mask layer 9 having an opening region 13 that overlaps with the intended location 11 of the label 10. In other words, the solder mask layer 9 is omitted in the region of the intended location 11 of the label 10, such that the desired recess 12 is formed in the intended location 11 by the solder mask layer 9 and the underlying copper layer 3. When the solder mask layer 9 is applied in a conventional application process, the opening region 13 of the solder mask layer 9 can also be provided effortlessly to form the recess 11 to receive the label 10. The solder mask layer 9 is applied before the solder paste 6 is printed, so the required solder mask layer 9 is baked onto the PCB 1.

[0038] According to Figures 4 to 6 In an example of the present invention, the deep recess 12 having more space for attaching the label 10 is created by providing both a copper-free area at the intended location 11 of the label and a solder mask layer 9 having an opening area 13 that overlaps with the intended location 11 of the label 10.

[0039] List of reference numerals in the attached diagram:

[0040] 1. Printed Circuit Board (PCB)

[0041] 2 electronic components

[0042] 3 copper layers

[0043] 4 Non-conductive substrate

[0044] 5 contact pads

[0045] 6 solder paste

[0046] 7 Reflow Template

[0047] 8 perforations

[0048] 9 solder resist layers

[0049] 10 tags

[0050] 11 Expected Position

[0051] 12 depressions

[0052] 13 Opening Area

Claims

1. A printed circuit board for mechanical support and electrical connection of an electrical or electronic component (2), the printed circuit board having conductive tracks and contact pads (5) and a label (10), the conductive tracks and the contact pads (5) being engraved or etched from at least one copper sheet layer (3) laminated onto a non-conductive substrate (4), and the label (10) being attached to the printed circuit board (1) at a predetermined location (11) prior to assembly processing. Its features are, The printed circuit board (1) sets the intended position (11) of the label (10) relative to the recess (12) around it. The intended location (11) of the label (10) is set as a copper-free area; the copper-free area at the intended location (11) is formed by etching the copper sheet layer (3) together with the formation of the conductive track and the contact pad (5); and the label (10) directly abuts against the non-conductive substrate (4). The recess (12) is created by providing a copper-free area at the intended location (11) of the label and a solder mask layer (9) having an opening area (13) that overlaps with the intended location (11) of the label, such that the recess (12) is formed in the intended location (11) by being surrounded by the solder mask layer (9) and the underlying copper sheet layer (3).

2. A method for manufacturing a printed circuit board (1) for mechanical support and electrical connection of an electrical component or electronic component (2), the method comprising the following steps: - Lamination of at least one copper sheet layer (3) onto a non-conductive substrate (4), and engraving or etching of conductive tracks and contact pads (5) from the copper sheet layer (3), - Attach the label (10) to the printed circuit board (1) at the intended location (11). The characteristic feature is that the intended position (11) of the label (10) is manufactured as a recess (12) relative to its surroundings. The intended location (11) of the label (10) is set as a copper-free area; the copper-free area at the intended location (11) is formed by etching the copper sheet layer (3) together with the formation of the conductive track and the contact pad (5); and the label (10) directly abuts against the non-conductive substrate (4). The recess (12) is created by providing a copper-free area at the intended location (11) of the label and a solder mask layer (9) having an opening area (13) that overlaps with the intended location (11) of the label, such that the recess (12) is formed in the intended location (11) by being surrounded by the solder mask layer (9) and the underlying copper sheet layer (3).

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