JPS63102399A - Multilayer printed interconnection board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A multilayer printed wiring board configured to regularly arrange modification pads that are electrically independent in addition to modification pads that are connected to through holes. This makes it possible to improve modifyability and eliminate the influence on the shrinkage rate during manufacturing.

[Industrial application field]

The present invention relates to a multilayer printed wiring board, and more specifically, to a multilayer printed wiring board that facilitates modification due to design changes and is easy to manufacture.

BACKGROUND OF THE INVENTION As electronic devices become smaller and more sophisticated, there are demands for higher density printed wiring boards, finer wiring patterns, and the like.

On the other hand, along with this, printed wiring boards are becoming more multilayered.

As described above, a multilayer printed wiring board with high-density packaging requires enormous man-hours and costs for designing and manufacturing.

Therefore, if a design change, design error, manufacturing defect, or defect occurs or is discovered after designing and manufacturing a multilayer printed wiring board, it would take a lot of man-hours and money to redesign and remanufacture all of them. will be wasted.

Therefore, in order to deal with manufacturing defects, design errors, design changes, etc., multilayer printed wiring boards are designed with redundancy so that the printed wiring board can be repaired quickly and economically. ing.

However, if you add redundancy to the multilayer printed wiring board,
In general, high-density packaging may be hindered.

Therefore, there is a need for a multilayer printed wiring board structure that is easy to modify and manufacture (and does not cause a decrease in packaging density).

[Conventional technology]

(First Conventional Method) As a first conventional method that provides redundancy to a multilayer printed wiring board to enable modification for design changes, etc., for example, modification pads shown in FIGS. 6 and 7 are used. The method is to install a

In FIG. 6, the leads 3 of the electronic component 2 are soldered to the footprint 4 on the multilayer printed wiring board l.

A lead pattern 5.7 is wired from the footprint 4 to the through hole 8, and the through hole 8 is connected to other signal wiring in either the surface layer or the inner layer of the multilayer printed wiring board 1. .

Note that in this description, unless otherwise specified, a through hole refers to a through hole that is electrically conductive by plating or the like, and the same applies to through holes in the following description.

At the middle position of the drawer pattern 5.7, there is a pad 6 for modification.
is the provision.

At the time of modification, as shown in FIG. 7, the drawer pattern 7 between the modification pad 6 and the through hole 8 is cut, and the repair wire 10 is soldered to the modification pad drawer.

Note that in the first conventional method described above, the footprint 4 is used for the structure in which the electronic component 2 is mounted on the multilayer printed wiring board l, but other methods may be used as the mounting structure for the electronic component 2. Structure: For example, lead 3 of electronic component 2
It is also possible to have a structure in which it is inserted into a through hole.

This conventional method is effective mainly when the through hole 8 is located in the area 20 outside the electronic component 2.

In this conventional method, in order to draw out all the drawer patterns 5.7 to the outside of the electronic component 2, the inner area 21 of the electronic component 2
Therefore, it has the disadvantage that it is not suitable for a board on which multiple bins of electronic components are mounted.

(Second Conventional Method) As a second conventional method that provides redundancy to a multilayer printed wiring board and allows modification for design changes, etc., for example, a double VIA shown in FIGS. 8 and 9 is used. In FIG. 8, on the surface IA of the multilayer printed wiring board 1, that is, the electronic component mounting surface, from the footprint 4 to which the lead 3 of the electronic component 2 is soldered,
It is drawn out to the through hole 23 via the drawing pattern 22.

On the rear surface IB of the multilayer printed wiring board 1, that is, the surface on which electronic components are not mounted, wiring is routed from the through hole 23 to another through hole 8 via the lead pattern 5.7.

This through hole 8 is connected to other signal wiring in either the surface layer or the inner layer of the multilayer printed wiring board l.

At the middle position of the drawer pattern 5.7, there is a pad 6 for modification.
is the provision.

At the time of modification, as shown in FIG. 9, the drawer pattern 7 between the modification pad 6 and the through hole 8 is cut, and the repair wire 10 is soldered to the modification pad 6, thereby performing the modification.

In this conventional method, since the through hole 23 is mainly present in the area 21 inside the electronic component 2, the electronic component mounting surface IA
This is effective when it is difficult to carry out modification work.

However, in a modification work in which the repair wire is wired only to the back surface IB of the multilayer printed wiring board l, even if the through hole 23 is present in the area 20 outside the electronic component 2, Use this method.

In the second conventional method, 1 of the footprint 4 of the electronic component 2 is
Two through holes 23.8 are required for each.

Therefore, the drawer pattern area becomes considerably large for electronic components with many bins.

Therefore, the mounting area for each electronic component 2 becomes larger.

As a result, the length of the wiring pattern between each electronic component 2 becomes long, which has a disadvantage in that it has a negative effect on speeding up the electronic device.

(Third Conventional Method) As a third conventional method, as shown in FIGS. 10 and 11, for example, the drawer in the area 20 outside the electronic component 2 has a drawer as shown in FIGS. Similar to the first conventional method, a method of installing a modification pad is used, and the drawer in the area 21 inside the electronic component 2 is provided with the second conventional method shown in FIGS. 8 and 9. Similarly, double VI
There is a method that uses a combination of A and a modification pad.

The third conventional method allows extraction in a smaller area than the first and second conventional methods, but the pad 6 to which the repair wire 10 is soldered during remodeling is located between the electronic component mounting surface IA and the back surface IB. The disadvantage is that it is dispersed among

Therefore, if it becomes necessary to modify the repair wires on the respective surfaces IA and IB so that they straddle the soldering pads, the through holes 8 in the vicinity as shown in FIG.
The repair wire 10 is connected by passing the repair wire 10 through it.

In this case, the conventional method involves passing a long repair wire 10 directly between the target pads.

However, the need for modification is often concentrated on some electronic components (in order to wire one signal line to many LSIs and electronic components, it is necessary to repair many lines from one modified part). In many cases, a repair wire 10 is used, and in this case, it is necessary to pass a large number of repair wires 10 through the through hole 8. It may not be possible to pass the large number of repair wires 10 through, and therefore, modification may not be possible.

In addition, in the third conventional method, when the soldering on the electronic component mounting surface IA is used to wire the repair wire between the bands, the electronic component 2 gets in the way, making modification difficult. There are also drawbacks.

[Problem that the invention seeks to solve]

This conventional method has problems such as poor remodelability, reduced packaging density, and increased wiring length.

The present invention was created in view of these points, and provides a multilayer printed wiring board with a structure that is excellent in remodelability, does not cause a decrease in packaging density, and does not affect the manufacturability of the multilayer printed wiring board. is intended to provide.

[Means for solving problems]

FIG. 1 is a sectional view of the principle of the present invention.

In FIG. 1, 1 is a multilayer printed wiring board, and 2 is an electronic component mounted on the printed wiring board 1. As shown in FIG.

4 is an example of a footprint or a first through hole or band for connecting the electronic component 2,
Show footprint.

As an example of the structure of the electronic component 2 when the footprint 4 is used as the connection structure of the electronic component 2, the electronic component printed wiring board has a lead 3, and the lead 3 is soldered to the footprint 4. .

8 is a second through hole for connecting the electronic component 2 to each layer of the multilayer printed wiring board l.

5.7 is a drawer pattern for connecting the soft print 4 and the second through hole 8.

A first modification pad 6 is provided at an intermediate position of the drawer pattern 5.7.

Reference numeral 9 denotes an electrically independent second modification pad, which is regularly arranged at a position opposite to the second through hole 8.

Note that the second modification pad 9 is a multilayer printed wiring board V.
It may be provided on either the component mounting surface IA on which the electronic component 2 of il is mounted, or the back surface IB.

Further, the second modification pads 9 may be arranged regularly around the periphery of the multilayer printed wiring board 1 itself, or around each electronic component 2, as long as they are arranged in pairs with the respective drawn-out through holes. It may be a position corresponding to .

[Effect]

If there is no need to change the design of this multilayer printed wiring board 1, the second modification pad 9 is not used.

If it is necessary to change the design, the drawer pattern 7 between the first modification pad 6 and the through hole 8 is cut as shown in FIG.

A repair wire 10 is connected to the first modification pad 6 by soldering or the like, and the repair wire 10 is soldered to the first modification pad 9.

From the second retrofit pad 9, repair wires 11 are connected to one or more other retrofit pads as required for design changes.

Therefore, even if multiple wirings are made from the footprint 4 due to this design change, only one repair wire 10 is required for wiring from the first modification pad drawer to the second modification pad 9. . Therefore, the total length of wiring due to design changes can be shortened, providing excellent remodelability.

In addition, since the second modification pads 9 are regularly arranged at positions that pair with the through holes 8, in the manufacturing process of the multilayer printed wiring board 1, a large number of modification pads 9 are placed on the multilayer printed wiring board l. Even if pads are provided, there is no fear that the shrinkage rate during firing will vary from part to part of the multilayer printed wiring board 1.

Therefore, the provision of the modification pad 9 causes
No distortion or warpage occurs in the manufactured multilayer printed wiring board 1.

In addition, when the second modification pad 9 to be connected in the design change is mounted on the back surface IB of the multilayer printed wiring board 1, the connection from the first modification pad drawer to the second modification pad 9 The repair wire 10 may be modified so as to pass through the through hole 8 or a separately provided through hole that is not plated and pass through the back surface.

〔Example〕

(Structure of Embodiment) FIGS. 3 and 4 show an embodiment of the present invention, in which FIG. 3 is a perspective view before modification, and FIG. 4 is a perspective view after modification.

In FIG. 3, in this embodiment, the modification pad 9, which is electrically independent, that is, not electrically connected to the electronic component 2, the through hole, etc., is on the back surface IB of the multilayer printed wiring board 1, and is not electrically connected to the electronic component 2 or the through hole. It is provided at a position directly behind the modification pad 6 connected to the hole 8.

This embodiment shows an example in which the area surrounded by the imaginary line A in FIG. An example drawn out to area 21 is shown.

In the area surrounded by the imaginary line B, a method using the above-mentioned double IA and a modification pad may be adopted.

When used in conjunction with the embodiment of the present invention, this method of using a double VIA may be used only when drawing out the electronic component 2 to the inner area 21.

By limiting in this way, not only the outer area 20 but also the inner area 21 of the electronic component 2 is used to keep the mounting area of the electronic component 2 as small as possible, and by using a double VIA. The drawbacks can be compensated as much as possible by the present invention.

(Remodeling work of the example) When remodeling, the drawer pattern 7 between the modification pad 6 and the through hole 8 on the surface IA is canted in the part within the imaginary line A in FIG. 4, and the repair wire 10 is modified. solder to pad 6.

Note that welding may be performed instead of soldering, and the same applies in the following description.

The repair wire 10 is passed through the through hole 8 and soldered to the modification pad 9 on the back surface IB of the multilayer printed wiring board 1.

Furthermore, a repair wire 11 is wired from this modification pad 9 to one or more targeted modification pads.

In addition, in Fig. 4, even in the part surrounded by imaginary line B,
Cant the drawer pattern 7 between the modification pad 6 and the through hole 8 on the back side IB, and wire the repair wire 10 between the modification pad 6 and the desired modification pad to carry out the modification. be.

(Remodelability of Example) Since the structure and modification work of the multilayer printed wiring board in this example are as described above, the electronic component 2 is mounted on the front surface IA of the multilayer printed wiring board 1, and the repair wire is mounted on the back surface IB. 10. Various modification work including the wiring in 11 will be carried out, and by utilizing the empty area on the back surface IB and providing electrically independent modification pads 9 in a regular arrangement, the surface IA will be improved. In combination with the modification pad 6, modification performance can be improved without affecting the mounting area of electronic components.

Since the modification pads 6 pulled out from all the soft prints 4 always have a spare modification pad 9 on their back side in a one-to-one ratio, modification work is easy.

The repair wires 10 and 11 are connected to the modification pad 6 on the surface IA.
Since most of the wires are wired on the back surface IB, except for a short portion from the wire to the through hole 8, the electronic component 2 does not interfere with the wiring work or the wire state.

Even if a large number of signals are output from the soft print 4 due to modification work, only one repair wire 10 is required to pass through the through hole 8, so there is a risk that modification performance will be limited by the inner diameter of the through hole 8. do not have.

Since the electrically independent modification pad 9 is arranged in a pair with the modification pad 6, for example, if an LSI is found to be defective after being installed, modification work can be concentrated on that part. However, it can accommodate all wiring patterns.

(Mountability of Example) In this example, since the mounting area of the electronic component 2 can be kept as small as possible as described above, the mounting density of the electronic component 2 is not affected (therefore, High-density mounting is possible while ensuring redundancy for modification.

(Manufacturability of Example) In this example, the electrically independent modification pad 9 is
Although it is provided at a position corresponding to the modification pad 6 on the opposite side, since the soft prints are generally arranged with a certain regularity on a multilayer printed wiring board, the electrically independent modification pad 9 is also provided on the multilayer printed wiring board. 1 are arranged uniformly with regularity.

Therefore, the modified pads 9 do not have imbalances such as concentration in a particular direction on the multilayer printed wiring board 1, and as a result, there is no risk of non-uniform shrinkage due to firing when manufacturing the multilayer printed wiring board.

Therefore, providing such a modification pad 8 does not cause problems in the manufacturing method.

(Cooling characteristics of the embodiment) In this embodiment, the repair wires 10 are all passed through the back surface IB of the multilayer printed wiring board 1, both in the outer area 20 and the inner area 21 of the electronic component. It is sufficient to use one repair wire 10 for each footprint 4 from the modification pad 6 on the front surface IA of the printed wiring board l to the modification pad 9 on the rear surface IB.

Therefore, on the surface, that is, the electronic component mounting surface IA, the repair wires are laid over a very short distance and in the minimum number necessary.

Therefore, while the multilayer printed wiring board 1 is in operation, the strong cooling wind flowing around the multilayer printed wiring board 1 to cool the electronic components 2 has an effect on the repair wire on the electronic component mounting surface IA. There is no need to consider this.

Therefore, even if the cooling air is strong, there is no need to provide a wire cover on the electronic component mounting surface IA to prevent wire breakage.

Therefore, deterioration of cooling characteristics due to covering the electronic component lead portion with a wire cover can be avoided.

Most of the repair wires can be accommodated on the back surface IB of the multilayer printed wiring board 1, so by providing the wire cover only on the back surface IB, it is possible to take measures against strong winds for cooling while maintaining the cooling effect.

(Application example) FIG. 5 shows an example of application of the present invention.

In FIG. 5, each print 4 and through hole 8 of each electronic component 2 are connected via a modification pad 6,
In addition to providing the structure of the present invention in which a spare modification pad 9 is provided on the back side thereof, a through hole 30 without plating and a multilayer printed wiring board l are provided in the vicinity of the through hole 8.
A large number of modification pads 31 and modification pads 32 are provided around the through hole 30 on each of the front surface IA and the back surface IB.

The through holes 30 and the modification pads 31, 32 serve as terminal portions of the repair wires, and are distributed or regularly arranged in empty spaces at appropriate positions within the multilayer printed wiring board l.

The through holes 30 can be formed with the same diameter, for example, in a drilling process for forming each through hole in the multilayer printed wiring board 1.

Depending on the need for modification, if a large number of repair wires are generated and one modification pad is not enough, or if the repair wires that should pass through the front and back surfaces are concentrated in one place, These through holes 30 and modification pads 3
1.32 is used.

Here, since the through-hole 30 is not plated, even if it is formed to the same drill hole diameter as a normal through-hole as described above, the inner diameter is larger than the through-hole after plating, and therefore the number of holes is larger. Can be threaded through book repair wire.

Moreover, since the terminal portions are disposed dispersedly or regularly within the multilayer printed wiring board 1 as described above, there is no need to modify any part of the multilayer printed wiring board 1. However, the terminal portions located close to each other can be used, and accordingly, redundancy can be further increased without greatly affecting the packaging density, and the reconfigurability can be improved.

〔Effect of the invention〕

As described above, according to the present invention, the structure is simple, has excellent remodelability, does not reduce the mounting density of electronic components, etc., and has no effect on the shrinkage rate during manufacturing of the multilayer printed wiring board. It does not give any shadow and is extremely useful in practical terms.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the principle of the present invention, Fig. 2 is a cross-sectional view showing modification of the multilayer printed wiring board of Fig. 1, Fig. 3 is a perspective view showing an embodiment of the present invention, and Fig. 4 is a cross-sectional view showing the modification of the multilayer printed wiring board of Fig. 1. Figure 5 is a perspective view showing an application example; Figure 6 is a sectional view of the first conventional method; Figure 7 is a modification of the multilayer printed wiring board shown in Figure 6. Fig. 8 is a cross-sectional view of the second conventional method; Fig. 9 is a perspective view of the back side of the multilayer printed wiring board shown in Fig. 8; and Fig. 10 is a third conventional method. Cross-sectional view of the method. FIG. 11 is a cross-sectional view showing modification of the multilayer printed wiring board of FIG. 10. 1 and 2, 1 is a multilayer printed wiring board, 2 is an electronic component, 3 is a lead of the electronic component, 4 is a footprint, 5.7 is a drawer pattern, and 6 is between the drawer patterns 5.7. The first modification pad provided, 8 is a through hole, and 9 is an electrically independent second modification pad.

Claims (1)

[Claims] A footprint (4) or a first through hole for soldering a lead (3) of an electronic component (2);
or a pad for soldering a leadless electronic component, and a second through hole (8) from the footprint (4) or the first through hole or the pad.
) in a multilayer printed wiring board (1) provided with a first modification pad (6) electrically connected between the patterns (5, 7) pulled out for connection to the electrically independent first modification pad (6); 2 modification pad (9) to the second modification pad (9).
A multilayer printed wiring board characterized in that the through-holes (8) are regularly arranged at positions that pair with the through-holes (8).