JPH0590441A - Leadless chip carrier - Google Patents

Abstract

PURPOSE:To obtain a leadless chip carrier which achieves an improved washing even when it is mounted to a mother board. CONSTITUTION:In a lead chip carrier with a conductor circuit 11 and a recessed part 16 for mounting electronic parts which are formed at a surface side of an insulation substrate 1, a pad 12 for mounting on a mother board 2 which is formed at the rear-surface side, and a through-hole 13 which electrically connects the conductor circuit 11 and the pad 12 for mounting, a rear-surface side of the insulation substrate 1 is provided with a recessed part 17 for washing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leadless chip carrier having excellent cleanability.

[0002]

2. Description of the Related Art Conventionally, leadless chip carriers include those shown in FIGS. As shown in FIG. 9, the leadless chip carrier 10 includes an insulating substrate 1 and a conductor circuit 11 formed on the front surface side of the insulating substrate 1.
A mounting pad 12 provided on the back side of the insulating substrate 1 for mounting on the mother board 2, and the mounting pad 12
And a through hole 13 for electrically connecting the conductor circuit 11 and the conductor circuit 11, and a recess 16 for mounting an electronic component is provided on the front surface side.

The insulating substrate 1 has a mother board 2
When mounted on the mounting pad 12, the mounting pad 12 is fixed to the pad 21 on the mother board 2 by the solder 3. A space 115 and a gap 105 are provided between the back surface of the insulating substrate 1 and the mother board 2. The space 115 includes a back surface 119 of the insulating substrate 1, a front surface 29 of the mother board 2,
It is inside the pad 21, the mounting pad 12, and the solder 3. Its thickness is 50-100 μm.
On the other hand, the gaps 105 are provided at appropriate intervals, and the mounting hud 12, the solder 3 and the pad 2 are connected by the solder 3.
1 and the insulating substrate 1 and the mother board 2.
Its thickness is the same as the space 115. The length is 1000 to 2000 μm.

Next, a method of mounting the leadless chip carrier 10 and the mother board 2 will be described. First, between the mounting pad 12 and the through hole 13 of the leadless chip carrier 10 and the pad 21 on the motherboard 2,
Flux is applied to facilitate soldering. And I
The mounting pad 12, the through hole 13, and the pad 21 on the motherboard are mounted by soldering by R reflow or the like. After that, the flux remaining from the solder is a kind of corrosive agent, and is therefore removed by cleaning after mounting. Then, the cleaning water at that time is the leadless chip carrier 10
Of the leadless chip carrier 10 from the outside of the leadless chip carrier 10 through the gap 105 formed between the pads.
The space 11 between the surface 19 of the motherboard 19 and the surface 29 of the motherboard 2
Send in between 5. Then, the above flux is washed.

[0005]

[Problems to be Solved] However, the space 11
As described above, the thickness of No. 5 is only 50 to 100 μm, and the cleaning liquid cannot sufficiently or hardly enter the space 115 in the cleaning after mounting. Even if the cleaning water enters, it is difficult to remove the remaining flux only by flowing as a laminar flow because the space 115 has a small thickness. In view of the above conventional problems, the present invention aims to provide a leadless chip carrier having excellent cleaning properties between the leadless chip carrier and the mother board.

[0006]

According to the present invention, an insulating substrate, a conductor circuit formed on the front surface side of the insulating substrate, a mounting pad provided on the rear surface side of the insulating substrate for mounting on a mother board,
A leadless chip carrier having a through hole for electrically connecting the mounting pad and the conductor circuit, and a recess for mounting an electronic component on the front surface side, wherein the insulating substrate has a back surface side. The leadless chip carrier is characterized in that a cleaning recess is provided in the.

In the present invention, the cleaning recess is provided on the back surface side of the insulating substrate as described above. The cleaning recess is formed to have a thickness of 100 to 300 μm, for example. Therefore, the thickness of the space between the leadless chip carrier and the mother board is as wide as 150 to 400 μm. If it is less than 100 μm, sufficient cleaning cannot be expected. On the other hand, if the thickness exceeds 300 μm, there is a problem that the thickness of the bottom surface of the recess for mounting an electronic component becomes thin and the electronic component cannot be sufficiently held. Further, it is preferable that the insulating substrate has a drain groove communicating from the cleaning recess to the outside. For example, the drainage grooves are provided at the four corners of the insulating substrate (see FIG. 6). As a result, the cleaning water can smoothly pass through the gap between the leadless chip carrier, the motherboard, and the mounting pad, etc., and enter the space, and a larger amount of cleaning water than before can be obtained. Flow into.
Then, it is thoroughly washed and becomes drainage from the drainage groove and flows out.

[0008]

In the leadless chip carrier of the present invention, the space between the leadless chip carrier and the mother board has a thickness of 150 to 400 .mu.m, which is 50 to 400 .mu.m. 100
It is much wider than μm. Therefore, when cleaning the leadless chip carrier, the cleaning water entering this space forms a turbulent flow. Therefore, a sufficient cleaning effect can be obtained. As described above, according to the present invention, it is possible to provide a leadless chip carrier having excellent cleanability between the leadless chip carrier and the mother board.

[0009]

Embodiment 1 A leadless chip carrier according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the leadless chip carrier 10 of this example has an insulating substrate 1, a conductor circuit 11, a mounting pad 12, and a through hole 13, and on the surface side of the insulating substrate 1 for mounting electronic components. A recess 16 and a cleaning recess 17 are provided on the back surface side. The insulating substrate 1 has a length of 1000 to
The 2000 μm mounting pad 12 is mounted on the pad 21 of the mother board 2 by the solder 3.

As shown in FIGS. 1 to 3, the space between the leadless chip carrier 10 and the mother board 2 is formed by the thickness of the mounting pad 12, the solder 3 and the mother board pad 21 (compared with the conventional case). The same) and a space 116 formed by the thickness of the cleaning recess 17 formed on the back surface side of the insulating substrate. And the space 115
(Thickness 50 to 100 μm) and space 116 (100 to 30
The thickness of the cleaning space 117, which is 0 μm), is 150 to 4
It becomes 00 μm. Others are the same as in the conventional example.

Next, the leadless chip carrier 10 described above.
The manufacturing method will be described with reference to FIGS. 4 and 5. First, as shown in FIG. 4A, the copper foil layers 110, 1 are formed on the surface.
An insulating substrate 1 having 20 is prepared. Next, FIG. 4 (b)
A through hole 130 is formed as shown in FIG.
As shown in, the electronic component mounting recess 16 is provided by counterboring. Further, as shown in FIG. 4D, a cleaning recess 17 is provided on the opposite side of the electronic component mounting recess 16 by counterboring.

Thereafter, as shown in FIG. 5 (a), metal plating 180 is applied to the entire surface of the insulating substrate 1, and then, as shown in FIG. 5 (b), the conductor circuit 11 and the mounting pads 12 are removed by etching. Form. Furthermore, FIG.
As shown in (c), the through hole 13 is cut at its central portion to form a semicircular through hole. Moreover, the cut end surface 15 is formed by this. The leadless chip carrier 10 thus obtained is soldered to the pad 21 of the mother board as described above at the mounting pad 12 and the arc-shaped through hole 13.

In this way, the leadless chip carrier shown in FIG. 1 is obtained. Note that FIG. 2 is a plan view of the leadless chip carrier as seen from the back surface side. 3 shows the solderless leadless chip carrier 1
FIG. 3 is a perspective view in which 0 is cut vertically along the line AA in FIG. 2 and viewed from the back surface side. 2 and 3 show a state in which the cleaning water W passes through the gap 105 formed between the pads as shown by the arrow, enters the cleaning space 117 inside, and cleans while forming a turbulent flow. .. After sufficient cleaning, it is discharged from another gap 105.

As is known from the above, in the leadless chip carrier 10 of this embodiment, a cleaning space 117 is formed between the mother board 2 and the conventional clearance 115, in addition to the clearance 116 of the cleaning recess 17. ing. Therefore, the cleaning water W that has entered the cleaning space 117 forms a turbulent flow and cleans the inside thereof well. After that, the turbulent cleaning water W is vigorously discharged through the gap 105 between the mounting pad 12 and the motherboard 2. Therefore, the flux and the like between the leadless chip carrier 10 and the mother board 2 are sufficiently washed and removed.

Second Embodiment Next, a second embodiment will be described with reference to FIGS. 6 and 7. In this example, the insulating substrate 1 of Example 1 is provided with a cleaning recess 1
Drainage grooves 19 communicating with the outside from 7 are provided at the four corners. The drain groove 19 has the same depth as the cleaning recess 17. Others are the same as in the first embodiment. At the time of cleaning, a large amount of cleaning water is supplied to the cleaning space 11 by the drain groove 19.
Can flow into 7. Further, in the cleaning space 117, a sufficient cleaning effect similar to that of the first embodiment can be obtained. Further, as shown in FIG. 4, the drainage grooves 19 are formed at the four corners at the same time when the cleaning recess shown in FIG. 4D is formed by counterboring. Others are the same as the method of manufacturing the insulating substrate of the first embodiment.

Third Embodiment Next, a third embodiment will be described with reference to FIG. This example shows a method of manufacturing a leadless chip carrier by joining an insulating substrate, which has been previously provided with through holes for forming the cleaning recess 17, with another substrate. That is,
First, as shown in FIG. 8A, a first substrate 100 having a copper foil layer 105 on one surface, a second substrate 160 having a copper foil layer 165 on one surface, and a prepreg 102 are prepared. The second substrate 160 and the prepreg 102 have through holes 166 and 1020 for providing the cleaning recess 17. next,
As shown in FIG. 8B, the first substrate 100 and the second substrate 160 are bonded to each other by thermocompression bonding with the prepreg 102 sandwiching the surfaces having no copper foil layer. As a result, the cleaning recess 17 is formed. Next, as shown in FIG. 8C, a through hole 130 is formed. And
As shown in FIG. 8D, an electronic component mounting recess 16 is provided on the front surface side. After that, as in the first embodiment, the entire insulating substrate is plated as shown in FIG.
3 is cut at its central portion to form a semicircular through hole. According to the present example, as shown in FIG. 8A, since the through hole 166 for forming the cleaning recess is provided in advance, the cleaning recess 17 is formed by counterboring as in the first embodiment.
Need not be formed. According to this example, the first embodiment
The same effect as can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a leadless chip carrier mounted on a mother board according to a first embodiment.

FIG. 2 is a back view of the leadless chip carrier according to the first embodiment.

FIG. 3 is a rear perspective view of the soldered leadless chip carrier taken along the line AA in FIG.

FIG. 4 is an explanatory diagram of a manufacturing process of the leadless chip carrier according to the first embodiment.

FIG. 5 is an explanatory view of the process following FIG.

FIG. 6 is a rear view of the leadless chip carrier according to the second embodiment.

FIG. 7 is a rear perspective view of the soldered leadless chip carrier taken along the line BB in FIG.

FIG. 8 is an explanatory diagram of a manufacturing process of a leadless chip carrier according to a third embodiment.

FIG. 9 is a cross-sectional view of a leadless chip carrier mounted on a motherboard in a conventional example.

FIG. 10 is a rear view of the leadless chip carrier in the conventional example.

[Explanation of symbols]

 1. ． ． Insulating substrate, 2. ． ． Motherboard, 3. ． ． Solder, 10. ． ． Leadless chip carrier, 11. ． ． Conductor circuit, 12. ． ． Mounting pad, 13. ． ． Through hole, 16. ． ． Recess for mounting electronic components, 17. ． ． Cleaning recess, 19. ． ． Drainage, 21. ． ． Pads on the motherboard,

Claims (2)

[Claims] 1. An insulating substrate, a conductor circuit formed on a front surface side of the insulating substrate, a mounting pad provided on a rear surface side of the insulating substrate for mounting on a mother board, the mounting pad and the conductor circuit. In a leadless chip carrier having a through hole for electrically connecting with each other and having a recess for mounting an electronic component on the front surface side, wherein the insulating substrate has a recess for cleaning on the back surface side. Leadless chip carrier characterized by. 2. The leadless chip carrier according to claim 1, wherein the insulating substrate has a drain groove communicating from the cleaning recess to the outside.