JPS59188995A - Method of solder connecting and inspecting electronic part and circuit board - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inspection method that is suitable for high-density packaging and facilitates evaluation of solder connections between dress electronic components and wiring boards.

[Prior art]

FIG. 1 is a schematic diagram showing a chip carrier type leadless electronic component soldered to a wiring board, and FIG. 2 is a sectional view thereof. In the figure, 1 is the leadless electronic component and 2 is the wiring board.

The procedure for soldering the leadless electronic component 1 to the wiring board 2 will be explained below. Normally, cream solder is printed by screen printing or the like on the trenchless wiring board 2 at the position where the leadless electronic component 1 is to be soldered. One print is made, and the leadless electronic component 1 is mounted thereon. Thereafter, the cream solder is heated with a reflow device to melt it, and the many terminals of the leadless electronic component 1 are connected to the conductor pattern 3 provided on the wiring board 2 by soldering.

By the way, in this soldering process, solder balls 5 may be generated around the solder joints 40, and the solder balls 5 are small balls of solder, but when leadless electronic components 1 are mounted in high density, this solder Since the ball 5 may cause a short circuit between the terminals of the leadless electronic component 1, it is necessary to prevent this from occurring.

Furthermore, after soldering, the flux contained in the cream solder remains on the underside of the leadless electronic component 1 as a residue 6, but since this flux 6 causes corrosion of the metal parts, it can be completely removed by cleaning. have to drop it.

In order to study these phenomena, it is first necessary to observe the relevant parts after the soldering process or cleaning process. In the case of the leadless electronic component 1 described above, the solder of the solder connection portion 4 is located outside the leadless electronic component 1, as shown in FIG. Since the structure is such that it is hidden underneath, and the gap 7 between the wiring board 2 and the leadless electronic component 1 is very narrow, solder balls 5 and flux generated on the underside of the leadless electronic component 1 can be easily removed. It is not possible to observe the residue 6 from the outside after the soldering process or after the cleaning process.

However, in leadless electronic components 1, such as chip carrier types, which have a large number of terminals and where adjacent terminals are close to each other, a so-called solder bridge, a phenomenon in which terminals are shorted by solder during the soldering process, is a problem. This solder bridge may occur and cause bad results in the product, but if this solder bridge also occurs on the underside of the leadless electronic component 1, it is impossible to directly observe it for the same reason as above.

Here, we will discuss the causes of solder balls 5, etc. One of the causes of solder balls 5 is that when melting cream semi(4), heating is performed rapidly. The flux components contained in the solder will boil, and the force will cause the cream solder to scatter and form solder balls 5, but this can be prevented by adjusting the speed in advance. I can do it.

1. Regarding the cause of solder blisters, it is thought that an oversupply of cream solder is present, and this can also be prevented by carefully considering the appropriate supply system.

However, in the actual manufacturing process, in addition to the above causes, the terminals of the leadless electronic component 1 and the degree of oxidation of the conductor pattern 3 formed on the wiring board 2, the degree of oxidation of the cream solder, the degree of oxidation of the conductor - Solder balls 5 and solder blitzes occur due to various conditions such as variations in the dimensions of the turn 30 and weather conditions, and the causes of flux residue 6 also vary.

It is extremely difficult to detect such changes in conditions in advance and take countermeasures against them. Therefore, it is necessary to observe solder balls 5, solder filaments, IJs, and flux residues 6 during inspections during the manufacturing process. , it is necessary to take countermeasures in the event of a strange situation.

However, as mentioned above, in the leadless electronic part 1, it is impossible to observe these solder balls 5, semi-IB F'IJ nozzles, and flux residue 6 from the outside; In this inspection method, the solder connection part 4 shown in Fig. 2 was destroyed and the solder balls 5 etc. on the lower side of the IJ-trace component 1 were observed. Part 4 There were shortcomings such as not being able to sufficiently observe the sword and overlooking unusual phenomena and making incorrect decisions.

In addition, it takes many man-hours for inspection, and during that time, the manufacturing process has to be interrupted, resulting in a large loss in B consideration.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned deficiencies and ruts in the prior art, and it is possible to sufficiently observe the bottom 1111 of a leadless electronic sound register, and the solder ball around the solder liquid FiWB and between the terminals. By accurately inspecting the occurrence of solder filaments, it is possible to completely prevent the occurrence of defective products (752) and to minimize the loss of time during inspection. Leadless electronic sound products and self-base (
If the purpose is to obtain a solder connection inspection method with anti-
It is.

[Development of invention]

In order to achieve the above-mentioned object, the present invention connects a leadless electronic component to a transparent wiring board by soldering, and observes and inspects the underside of the leadless electronic IB product through the transparent wiring board. This is what we do.

〔Example〕

FIG. 3 is a perspective view showing an embodiment of the present invention, in which 8 is a chip carrier-type IJ)"less electronic sound, 9 is a transparent wiring board made of, for example, glass as a substrate material, and 10 is the leadless electronic sound. This is a conductor pattern formed on a wiring board 9 corresponding to the terminals of a component 8.

The leadless electronic component 8 is soldered to the wiring board 9 in the same manner as in FIGS. 1 and 2. That is, cream solder is printed on the wiring board 9 at the position where the leadless electronic component 8 is to be soldered connected by a screen printing method or the like, and after the leadless electronic component 8 is mounted on the cream solder, it is heated by a reflow device. A large number of terminals of a leadless electronic component 8 and a conductive pattern 10 formed on a wiring board 9 are connected by soldering by melting cream solder. 11 is the solder connection portion thereof.

After this soldering process, if you look at the leadless electronic component 8 from the bottom surface of the wiring board 9, you can easily and fully observe the entire underside of the leadless electronic component 8 through the transparent wiring board 9. Flux residue 1 sticking to the solder balls 12 remaining on the bottom side of the electronic component 8 and the wiring board 9
The evaluation is performed by inspecting the presence or absence of a solder bridge 14 occurring between the terminals of the leadless electronic component 3 and the leadless electronic component 8.

Note that the transparent wiring board 9 described above has the same heat capacity as the wiring board that will become the product, but the soldering conditions will be different, so it is necessary to use the same board material or a material that is almost the same. . Ceramic boards and glass epoxy boards are commonly used wiring boards for products.
These are usually not transparent, so if the product's wiring board is a ceramic board, a transparent ceramic board may be used as the transparent wiring board 9 for inspection. If the substrate is a glass epoxy substrate, polyester substrates may be stacked on top of each other.

〔Effect of the invention〕

As explained above, the present invention uses a transparent wiring board as a wiring board to which leadless electronic components are soldered, when examining soldering conditions to suppress the generation of solder balls, flux residue, etc. Because the underside of leadless electronic components is seen through the wiring board after the soldering process, it is possible to easily and fully observe the solder joints and their surroundings on the underside of leadless electronic components. This has the effect of preventing errors in judgment because no phenomena are overlooked and accurate results are obtained.

Furthermore, since the present invention performs observation through a transparent wiring board as described above, it does not require many inspection steps and has the advantage that evaluation time can be significantly reduced.

Furthermore, when checking the effectiveness of cleaning performed after the soldering process and the presence or absence of solder bridges, accurate results can be obtained and evaluation time can be reduced for the same reason as described above.

-Furthermore, when the lot of cream solder or leadless electronic components changes during the manufacturing process, inspection for the occurrence of solder balls and solder bridges must be done quickly and accurately, otherwise there will be a lot of time wasted. However, if a transparent wiring board is used as a complete pilot, results can be obtained quickly and accurately as described above, reducing lost time and preventing the occurrence of defective products. This has the effect of making a significant contribution.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an electronic component soldered to a wiring board, FIG. 2 is a sectional view thereof, and FIG. 3 is an embodiment of the method for inspecting the solder connection between an electronic component and a wiring board according to the present invention. FIG. 8...Leadless electronic component 9...Wiring board 10
...Conductor pattern 11...Solder connection part 12...
Solder ball 13...Flux residue 14...
Handa Bridge Patent Grant 1; Attorney: Oki Electric Industry Co., Ltd. Agent, Patent Attorney: Takashi Kanakura Two Procedural Amendments (Voluntary) November 7, 1980 Commissioner of the Patent Office Kazu Wakasugi Failure 1, Indication of Case 1982 Patent Application No. 062362 No. 3, Relationship with the Amended Person Case Patent Applicant Address 1-7-12 Toranomon, Minato-ku, Tokyo Name (029) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 4, Representative Manager 5, Date of amendment order 7, Contents of amendment 1, Page 2 of the specification, line 19, ``...to suppress the occurrence...'' was replaced with ``...to suppress the occurrence...'' ” and correct it. 2. Page 8, line 3 of the specification: “...The soldering conditions are...
``...'' is corrected to ``...Soldering conditions are...''. 3. On page 8, line 16 of the specification, the phrase ``Soldering conditions for holding down'' will be corrected to ``Soldering conditions for holding down.''

Claims (1)

[Claims] 1. An inspection method for evaluating the presence or absence of solder balls, flux residue, solder bridges, etc. that occur on the underside of leadless electronic components when IJ-dressed electronic components and wiring boards are connected by soldering. The leadless electronic component is soldered onto a transparent wiring board having a conductor pattern corresponding to the terminals of the leadless electronic component, and the underside of the leadless electronic component is observed through the transparent wiring board. Features: A solder connection inspection method between electronic components and wiring boards.