JPH07321430A - Adhesive-coating-diameter measuring method of printed-wiring board and printed-wiring board - Google Patents

Abstract

PURPOSE:To obtain an adhesive-coating-diameter measuring method whose operating efficiency is enhanced by a method wherein a coating-diameter testing mark for a proper coating diameter is formed in advance on a printed-wiring board and the testing mark is compared with an adhesive-coating diameter. CONSTITUTION:Ringed testing marks 22, 22A which are not overlapped with a circuit pattern are formed on a printed-wiring board 20. The marks 22, 22A are used to test the coating diameter of small-diameter adhesives 14 and large- diameter adhesives 14A. Then, the printed-wiring board 20 on which the testing marks 22, 22A have been formed is sent to a dispenser. The dispenser feeds an adhesive, only for a prescribed coating time, to one out of the marks 22, 22A or to both of them. Then, it is checked whether or not the coating diameter of the adhesive is within a range of the ring width of the marks 22, 22A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simply measuring the coating diameter of an adhesive supplied by a dispenser for adhering a surface mount component to a printed wiring board, and a printed wiring board used in this method. It is a thing.

[0002]

2. Description of the Related Art In a high-density mounting printed wiring board,
Surface mount components (also called chip components) are widely used. When mounting this surface mount component, the component is usually adhered to the printed wiring board with an adhesive, that is, temporarily fixed, and soldered by a flow or reflow method.

A predetermined amount of the adhesive is supplied by a dispenser controlled by a computer. That is, the nozzle of the dispenser is moved and positioned to a coordinate position to be applied which is input in advance, and a predetermined amount of adhesive is discharged from the nozzle. Since the application amount of the adhesive needs to be changed depending on the size of the surface-mounted component to be adhered, the nozzle diameter of the dispenser or the ejection time of the adhesive is changed according to the component.

FIG. 3 is a diagram for explaining the dimensions of components and pads and the adhesive application state. In FIG. 3, (A) shows a size of a small chip part, for example, a size 1608 type part 10 and a size example of a pad 12 (unit of size is mm) in a standardized specification of Japan Electronic Machinery Manufacturers Association (EIAJ). For this part 10, about 1.0 mm between the pads 12, 12
In the gap of the adhesive agent 14 having a diameter D ₁ = 0.5 to 0.6 mm,
14 is applied in a circle. Similarly, in FIG. 3B,
Large chip components such as tantalum capacitors, eg 3
The size of the 216 type component 10A is shown. In this case, since the gap between the pads 12A and 12A is 2.0 to 2.4 mm, the adhesives 14A and 14A have a diameter D ₂ = 0.9 to 1.
It is applied in a circle of 1 mm.

[0005]

[Problems of the prior art] The dispenser used here is
A tube containing an adhesive is loaded into a syringe having an inner diameter of about 20 mm, and the inside of the syringe is pressurized (about 2 kg / cm ² ) to eject the adhesive from a nozzle.
When the inside of the syringe is pressurized with air pressure in this way, the smaller the amount of the adhesive remaining in the syringe, the more the space into which air enters.

However, if the space where air enters increases, the ejection response of the adhesive deteriorates. Since the coating time, that is, the time for applying the air pressure is usually controlled in units of 1/1000 seconds, the coating amount, that is, the coating diameter varies depending on the remaining amount of the adhesive even if the coating time is controlled to be constant.

FIG. 4 shows the residual amount L under the condition that the coating time is constant.
It is a figure which shows the relationship between a coating diameter D. As is clear from this figure, as the remaining amount L decreases, the space into which air enters increases and the responsiveness deteriorates, so the coating diameter D also decreases.
That is, the coating amount is reduced. As a result, this may cause improper fixing of the parts, falling off, misalignment, or the like.

To solve such a problem, conventionally, a method of measuring and confirming the coating diameter has been widely adopted. In this method, an adhesive is experimentally applied (trial ejection) to an appropriate position other than the component mounting position, and the applied diameter is confirmed with a microscope having a scale. Then, after confirming that the predetermined application diameter is achieved, the application is officially applied to the component mounting position. However, this method has a problem that the measurement work is troublesome and inefficient.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method for measuring an adhesive coating diameter, which can easily confirm the coating diameter without using a microscope with a scale and is suitable for improving work efficiency. The first purpose is to provide. A second object is to provide a printed wiring board used directly for carrying out this method.

[0010]

According to the present invention, an object of the present invention is to provide a method for measuring an application diameter of an adhesive for adhering surface-mounted components supplied to a printed wiring board by a dispenser, in which the appropriate application diameter is previously applied to the printed wiring board. Coating diameter test mark is provided, adhesive is supplied to the test mark by the dispenser, and the test mark is compared with the adhesive coating diameter. This is achieved by the diameter measuring method.

It is desirable that the test mark has a ring shape, and the inner diameter and the outer diameter thereof are set to the minimum and maximum of the allowable range of the coating diameter, and this mark is formed in the same step as the outer layer circuit pattern. it can.

A second object is that an application diameter test mark having a diameter substantially corresponding to an appropriate application diameter of the adhesive supplied from the dispenser is provided at a position not overlapping the outer layer circuit pattern. Achieved by a printed wiring board.

[0013]

EXAMPLE FIG. 1 is a partially enlarged view of a printed wiring board having a test mark, and FIG. 2 is a diagram showing a procedure of a measuring method. The printed wiring board 20 shown in FIG. 1 has ring-shaped test marks 22 and 2 at positions not overlapping the circuit pattern.
2A is provided. These marks 22, 22A
Are for testing the coating diameters of the small-diameter adhesive 14 and the large-diameter adhesive 14A shown in FIG. 3, respectively.

That is, the inner diameter of the mark 22 is equal to that of the adhesive 14
Is the minimum value (0.5 mm in FIG. 3A), and the outer diameter of the mark 22 is the maximum value (also 0.6 mm). Similarly, the inner diameter of the mark 22A is the minimum value of the coating diameter of the adhesive 14A (also 0.9 mm), and the outer diameter thereof is the maximum value (1.1 mm).

These marks 22 and 22A are formed in the same process as the outer layer circuit pattern. For example, as shown in FIG. 2, first, a copper clad laminate is prepared (step 100), and a circuit pattern and test marks 22 and 22A are formed on the surface thereof by a known photoetching method or the like (step 102). In the photo-etching method, a circuit pattern and marks 22,
The circuit pattern and the mark 2 are obtained by exposing and curing A, removing unnecessary photoresist, and performing an etching process.
2, 22A are formed.

The marks 22 and 22A may be formed by printing an etching resist on a printed wiring board by a screen printing method or the like and then performing an etching process.
The marks 22 and 22A may be applied by screen-printing ink independently of the circuit pattern. Further, writing may be performed using a laser beam or the like. As described above, the marks 22 and 22A may be those which can be easily visually recognized.

The printed wiring board 20 having the test marks 22 and 22A attached thereto is sent to a dispenser (not shown). The dispenser moves the nozzle to the coordinates of one of the marks 22 and 22A by computer control, and supplies the adhesive to one or both of the marks 22 and 22A for a predetermined application time (step 104). Then, it is confirmed whether the application diameter of the adhesive is within the range of the ring width of the marks 22 and 22A (step 10).
6).

That is, since the ring width of the marks 22 and 22A indicates the allowable range of the coating diameter of the marks 22 and 22A, if the coating diameter is within the range of the ring width, it is judged that the adhesive is a proper amount. To do. On the contrary, if the coating diameter is inside the ring, the adhesive is insufficient, and if it is outside the ring, the adhesive is excessive.

As described above, the comparison between the coating diameter and the marks 22 and 22A may be made by visual observation.
May be viewed through a magnifying lens if desired. Also C
It is also possible to read the image of the marks 22 and 22A after applying the adhesive with a CD image sensor or the like and confirm the application diameter by image processing.

When the coating diameter is insufficient by checking the coating diameter, that is, the coating amount is insufficient, the coating amount can be increased by, for example, increasing the coating time with a dispenser (step 108). After adjusting the application time in this way, the adhesive is formally applied to the component mounting position (step 110), and the surface mount component is mounted by the automatic mounter (step 112). That is, after the components are bonded to the adhesive, soldering is performed by the flow method. When soldering by the reflow method, it goes without saying that cream solder is supplied to the pad prior to mounting the components.

One test mark may be provided for each coating diameter used for one wiring board 20, but a plurality of marks corresponding to the coating diameter may be provided. In this case, after adjusting the coating time (step 108), it is possible to confirm the coating diameter again by performing a trial shot (step 104) using a different mark (step 106), so that the coating diameter can be further controlled. It can be performed with high precision.

It is desirable that the marks having different diameters are formed separately from each other as in the embodiment, but if the widths of the rings do not overlap, a plurality of marks may be formed in concentric circles.

[0023]

As described above, according to the first aspect of the invention, the printed wiring board is provided with the adhesive coating diameter test mark, and the adhesive is applied to this mark before the adhesive is applied to the official position with the dispenser. Since the coating diameter is measured by coating and comparing the coating diameter with the mark, the suitability of the coating diameter can be easily determined without using a microscope with a scale. Therefore, work efficiency is improved.

If the test mark is ring-shaped and the inner and outer diameters thereof are set to the minimum and maximum values of the coating diameter, it is extremely appropriate if the coating diameter is within this ring width. It can be easily determined and work efficiency is further improved (claim 2). If the test mark is formed in the same process as the outer layer circuit pattern, it is desirable that the mark can be formed without adding a special manufacturing process for the mark (claim 3). However, this mark may be printed by screen printing or the like. Further, according to the invention of claim 4, a printed wiring board directly used for carrying out this measuring method can be obtained.

[Brief description of drawings]

FIG. 1 is a partially enlarged view of a printed wiring board that is an embodiment of the present invention.

FIG. 2 is a diagram showing a procedure of a measuring method of the present invention.

FIG. 3 is a diagram showing a state where a pad size adhesive is applied.

FIG. 4 is a diagram showing a change in a coating diameter D with respect to a residual adhesive amount L of a dispenser.

[Explanation of symbols]

 10, 10A Surface mount component 12, 12A Pad 14, 14A Adhesive 20 Printed wiring board 22, 22A Test mark

Claims (4)

[Claims] 1. A method for measuring a coating diameter of an adhesive for adhering surface-mounted components, which is supplied to a printed wiring board by a dispenser, wherein a coating diameter test mark having an appropriate coating diameter is previously provided on the printed wiring board. Then, the adhesive is supplied to the test mark by the dispenser, and the test mark and the adhesive application diameter are compared with each other, to measure the adhesive application diameter of the printed wiring board. 2. The method for measuring the adhesive application diameter of a printed wiring board according to claim 1, wherein the test mark has a ring shape with the minimum and maximum values of the adhesive application diameter being the inner diameter and the outer diameter, respectively. 3. The method for measuring the adhesive coating diameter of a printed wiring board according to claim 1, wherein the test mark is formed in the same step as the outer layer circuit pattern of the printed wiring board. 4. A position not overlapping the outer layer circuit pattern,
A printed wiring board having a coating diameter test mark having a diameter substantially corresponding to an appropriate coating diameter of an adhesive supplied from a dispenser.