CN110933836A - Flexible circuit board, printed circuit board, rigid-flex board and manufacturing method thereof - Google Patents

Flexible circuit board, printed circuit board, rigid-flex board and manufacturing method thereof Download PDF

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Publication number
CN110933836A
CN110933836A CN201911141112.8A CN201911141112A CN110933836A CN 110933836 A CN110933836 A CN 110933836A CN 201911141112 A CN201911141112 A CN 201911141112A CN 110933836 A CN110933836 A CN 110933836A
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CN
China
Prior art keywords
pad
circuit board
ground
sub
signal
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CN201911141112.8A
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Chinese (zh)
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CN110933836B (en
Inventor
陈洲
胡方衍
王晶
郑庆立
周杰
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Accelink Technologies Co Ltd
Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
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Accelink Technologies Co Ltd
Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
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Priority to CN201911141112.8A priority Critical patent/CN110933836B/en
Publication of CN110933836A publication Critical patent/CN110933836A/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0237—High frequency adaptations
    • H05K1/025—Impedance arrangements, e.g. impedance matching, reduction of parasitic impedance
    • H05K1/0251—Impedance arrangements, e.g. impedance matching, reduction of parasitic impedance related to vias or transitions between vias and transmission lines
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0215—Grounding of printed circuits by connection to external grounding means
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/111—Pads for surface mounting, e.g. lay-out
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/117—Pads along the edge of rigid circuit boards, e.g. for pluggable connectors
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • H05K1/118—Printed elements for providing electric connections to or between printed circuits specially for flexible printed circuits, e.g. using folded portions
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/36—Assembling printed circuits with other printed circuits
    • H05K3/361—Assembling flexible printed circuits with other printed circuits
    • H05K3/363—Assembling flexible printed circuits with other printed circuits by soldering
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/4007—Surface contacts, e.g. bumps
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/05—Flexible printed circuits [FPCs]
    • H05K2201/058—Direct connection between two or more FPCs or between flexible parts of rigid PCBs
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09209—Shape and layout details of conductors
    • H05K2201/09372—Pads and lands
    • H05K2201/09481—Via in pad; Pad over filled via

Abstract

The embodiment of the invention discloses a flexible circuit board, a printed circuit board, a rigid-flex board and a manufacturing method thereof, wherein the flexible circuit board comprises: a first pad connected to the signal line and having at least two through holes; the at least two through holes are used for enabling the first bonding pad and the signal wire to achieve impedance matching.

Description

Flexible circuit board, printed circuit board, rigid-flex board and manufacturing method thereof
Technical Field
The embodiment of the invention relates to the technical field of electronics, in particular to a flexible circuit board, a printed circuit board, a rigid-flex board and a manufacturing method thereof.
Background
The soft and hard combined Board is an electronic product formed by electrically connecting a Flexible Printed Circuit (FPC) and a Printed Circuit Board (PCB) and is used for connecting and transmitting electrical signals.
In the related art, the quality of signals transmitted in the rigid-flex board is poor, which affects the reliability of the device provided with the rigid-flex board.
Disclosure of Invention
In view of this, embodiments of the present invention provide a flexible circuit board, a printed circuit board, a rigid-flex board and a method for manufacturing the same.
According to a first aspect of embodiments of the present invention, there is provided a flexible circuit board including:
a first pad connected to the signal line and having at least two through holes;
the at least two through holes are used for enabling the first bonding pad and the signal wire to achieve impedance matching.
Optionally, the first pad includes: a first via and a second via; wherein the first and second through holes are different in shape;
the first through hole is positioned at the first end of the first bonding pad;
the second through hole is positioned at the second end of the first bonding pad;
wherein the second end of the first pad is opposite the first end of the first pad; the distance between the second end of the first bonding pad and the edge of the flexible circuit board is smaller than the distance between the first end of the first bonding pad and the edge of the flexible circuit board.
Optionally, the first through hole is a circular hole;
the second through hole is a U-shaped hole.
Optionally, the at least two vias are configured to make a difference between the impedance of the first pad and the impedance of the signal line in a range of 0 ohm to 5 ohm.
According to a second aspect of the embodiments of the present invention, there is provided a printed circuit board including:
a second pad including a signal pad and a ground pad;
the length of the signal pad is smaller than that of the grounding pad.
According to a third aspect of the embodiments of the present invention, there is provided a rigid-flex board, including: a flexible circuit board according to the first aspect of the embodiment of the present invention, and a printed circuit board according to the second aspect of the embodiment of the present invention;
the size of the first bonding pad of the flexible circuit board is the same as that of the signal bonding pad of the second bonding pad of the printed circuit board;
the signal bonding pad of the first bonding pad is connected with the signal bonding pad of the second bonding pad;
and the grounding pad of the first pad is connected with the grounding pad of the second pad.
Optionally, the edge of the signal pad of the first pad is flush with the edge of the signal pad of the second pad;
a first end of the ground pad of the first pad is flush with a first end of the ground pad of the second pad;
a preset distance is reserved between the second end of the grounding bonding pad of the first bonding pad and the second end of the grounding bonding pad of the second bonding pad;
a first end of the ground pad of the first pad and a second end of the ground pad of the first pad are opposite ends; the distance between the first end of the grounding pad of the first pad and the edge of the flexible circuit board is greater than the distance between the second end of the grounding pad of the first pad and the edge of the flexible circuit board;
a first end of the ground pad of the second pad and a second end of the ground pad of the second pad are opposite ends; the distance between the first end of the grounding pad of the second pad and the edge of the printed circuit board is smaller than the distance between the second end of the grounding pad of the second pad and the edge of the printed circuit board.
Optionally, the signal pad of the first pad includes: a first differential signal sub-pad and a second differential signal sub-pad;
the signal pad of the second pad includes: a third differential signal sub-pad and a fourth differential signal sub-pad; wherein the third differential signal sub-pad is connected to the first differential signal sub-pad, and the fourth differential signal sub-pad is connected to the second differential signal sub-pad;
the ground pad of the first pad includes: a first ground sub-pad and a second ground sub-pad;
the ground pad of the second pad includes: a third ground sub-pad and a fourth ground sub-pad; wherein the third ground sub-pad is connected to the first ground sub-pad, and the fourth ground sub-pad is connected to the second ground sub-pad;
the first differential signal sub-pad is located between the first ground sub-pad and the second differential signal sub-pad;
the second differential signal sub-pad is positioned between the first differential signal sub-pad and the second ground sub-pad;
the third differential signal sub-pad is located between the third ground sub-pad and the fourth differential signal sub-pad;
the fourth differential signal sub-pad is located between the third differential signal sub-pad and the fourth ground sub-pad.
According to a fourth aspect of the embodiments of the present invention, there is provided a method for manufacturing a rigid-flex board, the method being used for manufacturing the rigid-flex board according to the third aspect of the embodiments of the present invention, the method including:
aligning a signal pad of a first pad of the flexible circuit board and a signal pad of a second pad of the printed circuit board;
welding the signal pad of the first pad and the signal pad of the second pad through at least two through holes on the signal pad of the first pad;
and welding the ground pad of the first pad and the ground pad of the second pad through at least two through holes on the ground pad of the first pad.
Optionally, the aligning the signal pad of the first pad of the flexible circuit board and the signal pad of the second pad of the printed circuit board includes:
aligning an edge of the signal pad of the first pad with an edge of the signal pad of the second pad.
According to the flexible circuit board, the printed circuit board, the rigid-flex board and the manufacturing method thereof, the at least two through holes are formed in the first bonding pad of the flexible circuit board, so that the first bonding pad can have a larger impedance adjusting range when being welded with bonding pads of other circuit boards, impedance matching can be better achieved, the probability that signals are reflected at the connection position of the signal line and the first bonding pad due to the impedance mutation of the first bonding pad and the signal line can be reduced, and the quality of transmitted signals is improved.
In addition, compared with the method that only one through hole is arranged on the first bonding pad, the method and the device provided by the embodiment of the invention can improve the soldering tin penetration amount of the first bonding pad and improve the soldering reliability by arranging at least two through holes on the first bonding pad.
Drawings
FIG. 1 is a schematic diagram of a flexible circuit board shown in accordance with an exemplary embodiment;
FIG. 2 is a schematic diagram of a printed circuit board shown in accordance with an exemplary embodiment;
FIG. 3 is a schematic diagram illustrating a rigid-flex board according to an exemplary embodiment;
FIG. 4a is a schematic diagram of another flexible circuit board shown in accordance with an exemplary embodiment;
FIG. 4b is a schematic diagram of another printed circuit board shown in accordance with an exemplary embodiment;
fig. 5 is a flowchart illustrating a method of fabricating a rigid-flex board according to an exemplary embodiment.
Detailed Description
The technical solution of the present invention will be further elaborated with reference to the drawings and the embodiments. While exemplary implementations of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The present invention is more particularly described in the following paragraphs with reference to the accompanying drawings by way of example. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
In the embodiment of the present invention, the term "a is connected to B" includes A, B where a is connected to B in contact with each other, or A, B where a is connected to B in a non-contact manner with other components interposed therebetween.
In the embodiments of the present invention, the terms "first", "second", and the like are used for distinguishing similar objects, and are not necessarily used for describing a particular order or sequence.
The technical means described in the embodiments of the present invention may be arbitrarily combined without conflict.
Fig. 1 is a schematic diagram of a flexible circuit board 1000 shown in accordance with an example embodiment. Referring to fig. 1, the flexible circuit board 1000 includes:
a first pad 1100 connected to the signal line and having at least two through holes;
the at least two through holes are used for enabling the first bonding pad 1100 to be in impedance matching with the signal line.
Illustratively, the flexible circuit board 1000 may include: the flexible circuit board is applied to the light emitting assembly. For example, the flexible circuit board can be applied to a flexible circuit board in a light emitting assembly for 25G signal communication.
The first pads 1100 on the flexible circuit board 1000 may make electrical connections with pads on other circuit boards. When signals are transmitted between the flexible circuit board and other circuit boards, the signals pass through the connection part of the first bonding pad and the bonding pad on the other circuit boards.
The constituent material of the first pad may be a metal, for example, copper, etc. By providing at least two through holes on the first pad, the area of the first pad can be changed. The impedance of the first pad is related to the area of the first pad.
For example, the impedance of the first pad may be inversely related to the area of the first pad. Specifically, when the sum of the areas of at least two of the through holes increases, the area of the first pad decreases, so that the impedance of the first pad increases; when the sum of the areas of the at least two vias is decreased, the area of the first pad is increased so that the impedance of the first pad is decreased.
The first pad 1100 performing impedance matching with the signal line may include: the impedance of the first pad 1100 is equal to the impedance of the signal line, or the absolute value of the difference between the impedance of the first pad 1100 and the impedance of the signal line is less than 5 ohms.
When signals are transmitted between the flexible circuit board and other circuit boards, and the impedance of the connecting part of the first bonding pad and the bonding pads on other circuit boards is not matched with the impedance of the signal wire, impedance mutation exists at the connecting part of the first bonding pad and the bonding pads on other circuit boards, so that the transmitted signals are reflected, signal energy loss is caused, the signal quality is influenced, and the corresponding optical devices cannot normally work.
When signals are transmitted between the flexible circuit board and other circuit boards, and the impedance of the connecting part of the first bonding pad and the bonding pads on other circuit boards is matched with the impedance of the signal wire, the signals cannot be reflected at the connecting part of the first bonding pad and the bonding pads on other circuit boards, so that the signal quality is guaranteed, and the reliability of corresponding optical devices is further guaranteed.
According to the embodiment of the disclosure, the area of the first bonding pad is changed by arranging the at least two through holes on the first bonding pad of the flexible circuit board, so that the first bonding pad can have a larger impedance adjusting range when being welded with bonding pads of other circuit boards, thereby better realizing impedance matching, reducing the probability of signal reflection at the connection position of the signal line and the first bonding pad caused by impedance mutation of the first bonding pad and the signal line, and improving the quality of transmitted signals.
In addition, compared with the method that only one through hole is arranged on the first bonding pad, the method and the device provided by the embodiment of the invention can improve the soldering tin penetration amount of the first bonding pad and improve the soldering reliability by arranging at least two through holes on the first bonding pad.
In some embodiments, referring to fig. 1, the first pad 1100 includes: a first via 1101 and a second via 1102; wherein the first via 1101 and the second via 1102 have different shapes;
a first via 1101 at a first end of the first pad 1100;
a second via 1102 at a second end of the first pad 1100;
wherein the second end of the first pad 1100 is an opposite end of the first pad 1100; the distance between the second end of the first pad 1100 and the edge of the flexible circuit board 1000 is smaller than the distance between the first end of the first pad 1100 and the edge of the flexible circuit board 1000.
Referring to fig. 1, the first via 1101 is closer to the inner side of the flexible circuit board 1000 and is farther from the edge of the flexible circuit board 1000 than the second via 1102.
Compared with the method that at least two through holes are arranged at the same end of the first bonding pad, the first through hole 1101 and the second through hole 1102 are arranged at the two opposite ends of the first bonding pad 1100, the uniformity of distribution of the soldering tin on the first bonding pad can be improved, and the reliability of welding is improved.
In addition, through setting up the first through-hole and the second through-hole that the shape is different, can improve the flexibility to the regulation and control of first pad area, and then when the pad welding of first pad and other circuit boards, improve the flexibility to impedance adjustment.
Illustratively, referring to fig. 1, the first through-hole 1101 may be a circular hole; the second through hole 1102 may be a U-shaped hole; wherein the opening of the U-shaped hole is flush with the second end of the first pad 1100.
Fig. 2 is a schematic diagram of a printed circuit board 2000 shown in accordance with an example embodiment. Referring to fig. 2, the printed circuit board 2000 includes:
second pads including signal pad 2120 and ground pad 2110;
the length of signal pad 2120 is less than the length of ground pad 2110.
As shown in fig. 2, the signal pad 2120 of the second pad and the ground pad 2110 of the second pad may each be rectangular, wherein the length of the signal pad 2120 is smaller than the length of the ground pad 2110.
Typically, the first pads on the flexible circuit board are the same size as the signal pads of the second pads on the printed circuit board. Because the signal pad length of second pad is less than the ground connection pad length of second pad, consequently, in flexible circuit board and printed circuit board welding process, can align the signal pad of first pad with the signal pad of second pad as the benchmark, reduce the counterpoint deviation of welded, improve the welding yield, guarantee the quality of soft or hard combination board.
In addition, because the length of the ground pad of the second pad is greater than that of the ground pad of the first pad, when the ground pad of the second pad and the ground pad of the first pad are welded, the soldering tin can climb to the area, beyond the ground pad of the first pad, of the ground pad of the second pad through the second through hole and is coated between the edge of the ground pad of the first pad and the ground pad of the second pad, and the welding reliability between the ground pad of the first pad and the ground pad of the second pad can be improved.
Fig. 3 is a schematic diagram illustrating a rigid-flex board 3000 according to an exemplary embodiment. Referring to fig. 3, the rigid-flex board 3000 includes: the flexible circuit board 1000 provided by the embodiment of the present disclosure, and the printed circuit board 2000 provided by the embodiment of the present disclosure;
the size of the first pad of the flexible circuit board 1000 is the same as the size of the signal pad of the second pad of the printed circuit board 2000;
a signal pad 1110 of the first pad connected to a signal pad 2110 of the second pad;
the ground pad 1120 of the first pad is connected to the ground pad 2120 of the second pad.
The signal pad 1110 of the first pad and the ground pad 1120 of the first pad have the same shape and the same size.
Because the signal pad of the first pad is the same as the signal pad of the second pad in size, and the signal pad length of the second pad is smaller than the ground pad length of the second pad, therefore, in the welding process of the flexible circuit board and the printed circuit board, the signal pad of the first pad and the signal pad of the second pad can be used as a reference to be aligned, the welding contraposition deviation is reduced, the welding yield is improved, and the quality of the soft-hard combined board is ensured.
In addition, because the length of the ground pad of the second pad is greater than that of the ground pad of the first pad, when the ground pad of the second pad and the ground pad of the first pad are welded, the soldering tin can climb to the area, beyond the ground pad of the first pad, of the ground pad of the second pad through the second through hole and is coated between the edge of the ground pad of the first pad and the ground pad of the second pad, and the welding reliability between the ground pad of the first pad and the ground pad of the second pad is improved.
In some embodiments, an edge of the signal pad of the first pad is flush with an edge of the signal pad of the second pad;
a first end of the ground pad of the first pad is flush with a first end of the ground pad of the second pad;
a preset distance is reserved between the second end of the grounding bonding pad of the first bonding pad and the second end of the grounding bonding pad of the second bonding pad;
a first end of the ground pad of the first pad and a second end of the ground pad of the first pad are opposite ends; the distance between the first end of the grounding pad of the first pad and the edge of the flexible circuit board is greater than the distance between the second end of the grounding pad of the first pad and the edge of the flexible circuit board;
a first end of the ground pad of the second pad and a second end of the ground pad of the second pad are opposite ends; the distance between the first end of the grounding pad of the second pad and the edge of the printed circuit board is smaller than the distance between the second end of the grounding pad of the second pad and the edge of the printed circuit board.
In some embodiments, as shown with reference to fig. 4a, the signal pad of the first pad includes: a first differential signal sub-pad 1121 and a second differential signal sub-pad 1122;
referring to fig. 4b, the signal pad of the second pad includes: a third differential signal sub-pad 2121 and a fourth differential signal sub-pad 2122; wherein the third differential signal sub-pad 2121 is connected to the first differential signal sub-pad 1121, and the fourth differential signal sub-pad 2122 is connected to the second differential signal sub-pad 1122;
the ground pad of the first pad includes: a first ground sub-pad 1111 and a second ground sub-pad 1112;
the ground pad of the second pad includes: third and fourth ground sub-pads 2111 and 2112; wherein the third ground sub-pad 2111 is connected to the first ground sub-pad 1111, and the fourth ground sub-pad 2112 is connected to the second ground sub-pad 1112;
a first differential signal sub-pad 1121 positioned between the first ground sub-pad 1111 and the second differential signal sub-pad 1122;
a second differential signal sub-pad 1122 between the first differential signal sub-pad 1121 and the second ground sub-pad 1112;
a third differential signal sub-pad 2121 located between the third ground sub-pad 2111 and the fourth differential signal sub-pad 2122;
and a fourth differential signal sub-pad 2122 between the third differential signal sub-pad 2121 and the fourth ground sub-pad 2112.
When the hard-soft combined board is used to transmit differential signals, the first differential sub-signal is transmitted through the first differential signal sub-pad 1121 and the third differential signal sub-pad 2121, and the second differential sub-signal is transmitted through the second differential signal sub-pad 1122 and the fourth differential signal sub-pad 2121. The first differential sub-signal and the second differential sub-signal have the same amplitude and opposite phases. For example, when the first differential sub-signal is a positive (P) signal, the second differential sub-signal is a negative (N) signal; when the first differential sub-signal is a negative (N) signal, the second differential sub-signal is a positive (P) signal.
Example 1
Since a 25G direct Modulated semi-conductor Laser (DML) emits high-speed signals, the differential impedance of the link is required to be 50 ohms. In the prior art, impedance abrupt change exists at the welding position of a flexible circuit board and a printed circuit board, which can cause signal reflection, further influences the quality of 25G good link signals, and causes that an optical device can not work normally.
The rigid-flex board 3000 provided in this example can be applied to signal transmission in the field of optical communications. For example, it may be applied in a light emitting module. In particular, it can be applied to 25G direct modulation lasers.
Taking the application of the rigid-flex board 3000 to a 25G direct modulation laser as an example, referring to fig. 4a, the first ground sub-pad 1111, the first differential signal sub-pad 1121, the second differential signal sub-pad 1122, and the second ground sub-pad 1112 are disposed on the flexible circuit board 1000 in the same area and shape. Also, the first ground sub-pad 1111, the first differential signal sub-pad 1121, the second differential signal sub-pad 1122, and the second ground sub-pad 1112 are each provided with one circular first via 1101 and one U-shaped second via 1102. The first via 1101 is located near the inside of the board of the flexible circuit board 1000, and the second via 1102 is located near the board edge of the flexible circuit board 1000.
Illustratively, in the first ground sub-pad 1111, a width W of the first ground sub-pad114.75 mils (mil), the first via 1101 has an aperture of 4 mils, and a distance D between a center of the first via 1101 and the first end of the first ground sub-pad1Is 7mil, the distance D between the center of the first through hole 1101 and the bottom of the U-shaped hole27.77mil, the distance D between the bottom of the U-shaped via and the second end of the first ground sub-pad 11113It was 12.79 mil.
Referring to fig. 4b, a third ground sub-pad 2111, a third differential signal sub-pad 2121, a fourth differential signal sub-pad 2122, and a fourth ground sub-pad 2112 are provided on the printed circuit board 2000. The third and fourth ground sub-pads 2111 and 2112 are the same in shape and size, the third and fourth differential signal sub-pads 212 and 2122 are the same in shape and size, and the length of the third ground sub-pad 2111 is greater than the length of the third differential signal sub-pad 2121. Illustratively, the length of the third ground sub-pad 2111 is 0.2 millimeters longer than the length of the third differential signal sub-pad 2121.
According to the rigid-flex board provided by the example, through the design of the first through hole and the second through hole on the bonding pad and the flexible circuit board, the impedance sudden change at the welding position of the flexible circuit board and the printed circuit board can be well controlled. Through experimental tests, the differential impedance of the welding position of the flexible circuit board and the printed circuit board is in the range of 45 ohms to 55 ohms, and can be well matched with the differential impedance of 50 ohms in a link.
And, the second through-hole of circular shape first through-hole and U-shaped can promote the tin volume of permeating for soldering tin evenly distributed promotes the welding reliability between the second pad of first pad and printed circuit board at flexible circuit board's first pad both ends.
In addition, because the printed circuit board is provided with the third grounding sub-pad and the third differential signal sub-pad which are different in length, when the printed circuit board is welded with the flexible circuit board, the third differential signal sub-pad can be used as a reference to be aligned with the first differential signal sub-pad on the flexible circuit board, the welding alignment deviation is reduced, and the welding yield is improved.
In the related art, in order to facilitate soldering between the flexible printed circuit board and the printed circuit board, a frame is generally screen-printed at a position where the surface of the printed circuit board is soldered, so as to facilitate soldering alignment between the flexible printed circuit board and the printed circuit board. But with the rapid progress of technology, the size of the printed circuit board is gradually reduced, the line spacing of the wiring on the printed circuit board is narrower and narrower, and the flexible circuit board and the printed circuit board do not have enough space for silk-screen printing of the frame body. Therefore, when the first bonding pad of the flexible circuit board and the second bonding pad of the printed circuit board are welded, alignment is completely performed by manual experience, alignment errors are large, and welding yield is low.
In addition, the sizes of the tin-through holes on the flexible circuit board in the related art are unreasonable, so that on one hand, the abrupt change between the impedance of the welding position of the first bonding pad and the second bonding pad and the impedance of the signal wire is large, the quality of a transmitted signal is affected, and even the response optical device cannot work normally. On the other hand, the unreasonable size of the tin-penetrating hole on the flexible circuit board can also lead to insufficient tin penetration in the soldering process, and lead to unreliable soldering.
Fig. 5 illustrates a method for manufacturing a rigid-flex board according to an exemplary embodiment, which is used to manufacture a rigid-flex board 3000 provided by the embodiment of the present disclosure. Referring to fig. 5, the method includes the steps of:
s100: aligning a signal pad of a first pad of the flexible circuit board and a signal pad of a second pad of the printed circuit board;
s200: welding the signal bonding pad of the first bonding pad and the signal bonding pad of the second bonding pad through at least two through holes on the signal bonding pad of the first bonding pad; and welding the grounding pad of the first pad and the grounding pad of the second pad through at least two through holes on the grounding pad of the first pad.
According to the embodiment of the disclosure, the area of the first bonding pad is changed by arranging the at least two through holes on the first bonding pad of the flexible circuit board, so that the first bonding pad and the second bonding pad can have a larger impedance adjusting range when being welded, impedance matching between the welding position of the first bonding pad and the second bonding pad and a signal line is realized, the probability of signal reflection at the welding position of the first bonding pad and the second bonding pad caused by impedance mutation can be reduced, and the quality of transmitted signals is improved.
In addition, compared with the method that only one through hole is arranged on the first bonding pad, the method and the device for soldering the first bonding pad can improve the soldering tin penetration amount of the first bonding pad, improve the reliability of soldering between the first bonding pad and the second bonding pad and ensure the performance of the device by arranging at least two through holes on the first bonding pad.
Exemplarily, S100 may include: the edge of the signal pad of the first pad is aligned with the edge of the signal pad of the second pad.
Because the signal pad size of first pad and second pad is the same, and the signal pad length of second pad is less than the ground connection pad length of second pad, consequently, in flexible circuit board and printed circuit board welding process, can regard the signal pad of first pad and the signal pad of second pad as the benchmark and align, reduce the welded counterpoint deviation, improve the welding yield, guarantee the quality of soft or hard combined board.
In addition, because the length of the ground pad of the second pad is greater than that of the ground pad of the first pad, when the ground pad of the second pad and the ground pad of the first pad are welded, the soldering tin can climb to the area, beyond the ground pad of the first pad, of the ground pad of the second pad through the second through hole and is coated between the edge of the ground pad of the first pad and the ground pad of the second pad, and the welding reliability between the ground pad of the first pad and the ground pad of the second pad can be improved.
Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: a mobile storage device, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The methods disclosed in the several method embodiments provided by the present invention can be combined arbitrarily without conflict to obtain new method embodiments.
Features disclosed in several of the product embodiments provided by the invention may be combined in any combination to yield new product embodiments without conflict.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims (10)

1. A flexible circuit board, comprising:
a first pad connected to the signal line and having at least two through holes;
the at least two through holes are used for enabling the first bonding pad and the signal wire to achieve impedance matching.
2. The flexible circuit board of claim 1,
the first pad includes: a first via and a second via; wherein the first and second through holes are different in shape;
the first through hole is positioned at the first end of the first bonding pad;
the second through hole is positioned at the second end of the first bonding pad;
wherein the second end of the first pad is opposite the first end of the first pad; the distance between the second end of the first bonding pad and the edge of the flexible circuit board is smaller than the distance between the first end of the first bonding pad and the edge of the flexible circuit board.
3. The flexible circuit board of claim 2,
the first through hole is a circular hole;
the second through hole is a U-shaped hole.
4. The flexible circuit board of claim 1,
the at least two through holes are used for enabling the difference value between the impedance of the first bonding pad and the impedance of the signal wire to be in the range of 0 ohm to 5 ohm.
5. A printed circuit board, comprising:
a second pad including a signal pad and a ground pad;
the length of the signal pad is smaller than that of the grounding pad.
6. A rigid-flex board, comprising: the flexible circuit board according to any one of claims 1 to 4, and the printed circuit board according to claim 5;
the size of the first bonding pad of the flexible circuit board is the same as that of the signal bonding pad of the second bonding pad of the printed circuit board;
the signal bonding pad of the first bonding pad is connected with the signal bonding pad of the second bonding pad;
and the grounding pad of the first pad is connected with the grounding pad of the second pad.
7. The rigid-flex board according to claim 6,
the edge of the signal pad of the first pad is flush with the edge of the signal pad of the second pad;
a first end of the ground pad of the first pad is flush with a first end of the ground pad of the second pad;
a preset distance is reserved between the second end of the grounding bonding pad of the first bonding pad and the second end of the grounding bonding pad of the second bonding pad;
a first end of the ground pad of the first pad and a second end of the ground pad of the first pad are opposite ends; the distance between the first end of the grounding pad of the first pad and the edge of the flexible circuit board is greater than the distance between the second end of the grounding pad of the first pad and the edge of the flexible circuit board;
a first end of the ground pad of the second pad and a second end of the ground pad of the second pad are opposite ends; the distance between the first end of the grounding pad of the second pad and the edge of the printed circuit board is smaller than the distance between the second end of the grounding pad of the second pad and the edge of the printed circuit board.
8. The rigid-flex board according to claim 6,
the signal pad of the first pad includes: a first differential signal sub-pad and a second differential signal sub-pad;
the signal pad of the second pad includes: a third differential signal sub-pad and a fourth differential signal sub-pad; wherein the third differential signal sub-pad is connected to the first differential signal sub-pad, and the fourth differential signal sub-pad is connected to the second differential signal sub-pad;
the ground pad of the first pad includes: a first ground sub-pad and a second ground sub-pad;
the ground pad of the second pad includes: a third ground sub-pad and a fourth ground sub-pad; wherein the third ground sub-pad is connected to the first ground sub-pad, and the fourth ground sub-pad is connected to the second ground sub-pad;
the first differential signal sub-pad is located between the first ground sub-pad and the second differential signal sub-pad;
the second differential signal sub-pad is positioned between the first differential signal sub-pad and the second ground sub-pad;
the third differential signal sub-pad is located between the third ground sub-pad and the fourth differential signal sub-pad;
the fourth differential signal sub-pad is located between the third differential signal sub-pad and the fourth ground sub-pad.
9. A method for manufacturing a rigid-flex board, wherein the method is used for manufacturing the rigid-flex board according to any one of claims 6 to 8, and the method comprises:
aligning a signal pad of a first pad of the flexible circuit board and a signal pad of a second pad of the printed circuit board;
welding the signal pad of the first pad and the signal pad of the second pad through at least two through holes on the signal pad of the first pad;
and welding the ground pad of the first pad and the ground pad of the second pad through at least two through holes on the ground pad of the first pad.
10. The method of claim 9, wherein said aligning the signal pad of the first pad of the flexible circuit board and the signal pad of the second pad of the printed circuit board comprises:
aligning an edge of the signal pad of the first pad with an edge of the signal pad of the second pad.
CN201911141112.8A 2019-11-20 2019-11-20 Flexible circuit board, printed circuit board, rigid-flex board and manufacturing method thereof Active CN110933836B (en)

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