JPH0344043A - Laser marking method - Google Patents

Abstract

PURPOSE:To make a mark stand out from a trimming part, and make it easy to recognize the mark, by projecting laser light on the part except a mark forming region, and trimming a mold surface. CONSTITUTION:A mold surface is constituted of the following; an outer periphery frame part 4, a part 5 serving as a mark constituted of English characters, a part which is constituted of said part 5 and a linkage part 6 connecting said part 5 with the outer periphery frame 4 and not irradiated with laser light, and a part 7 where said mold surface is subjected to trimming by projecting laser light. The part 5 serving as a mark constituted of English characters L and C protrudes from the part 7 where the above mold surface is subjected to trimming, and can make the English character part 5 stand out. As the result, the mark 5 can be easily made clear at the time of resin molding, even in the case where the mold surface of a mold body 2 has luster due to the metal mold of transfer molding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technology for modifying a marking method in which a mark is engraved on a plastic package or the like using a laser beam.

[Conventional technology]

A mark such as a product name or company name is attached to the surface of a molded body (hereinafter simply referred to as a package) of a resin molded semiconductor device.

As a means for attaching this mark, there is an ink application (printing) method. In this printing method, for example, 150C
It takes about 2 hours to dry. For this reason, the solder surface of the package lead is oxidized by heat, and alloying of the solder and the lead occurs. inhibit sex. In addition, marks made using this ink marking method are prone to mark defects (disappearance, chipping, etc.) due to incomplete printing, and
Defects were likely to occur, such as marks disappearing by the time the product was delivered to the customer.

Therefore, in order to solve this problem, leather marking has been proposed. For example, the marking method is known from Japanese Patent Laid-Open No. 110001/1983.

By the way, in the conventional laser method, the brown mark part is engraved on the black resin mold surface by carbonizing the resin with laser light, so the contrast between the brown mark part and the black bare surface is unclear. This has the disadvantage that it is difficult to distinguish clearly. In addition, after resin molding, liquid honing to remove burr clouds the surface of the resin mold, making it difficult to see marks. Furthermore, when the surface of the printed wiring board is coated with a protective film made of polyimide or the like, there is a drawback that the contrast of the laser mark deteriorates and it tends to become unclear. Particularly, when a laser mark is engraved on the surface of an ultra-small transistor package of, for example, a size of 1.5ii×2.9 mm, the mark becomes extremely small, so that the above-mentioned drawbacks become even more noticeable.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel laser marking method that can overcome the drawbacks of the prior art described above.

[Means to solve problems]

A brief summary of representative indulgences of the invention disclosed in this application is as follows.

The present invention does not irradiate laser light onto the part to be marked,
The feature is that the mold surface is trimmed by irradiating laser light to other parts, and the mark is raised from the trimmed part.

[Effect]

As described above, according to the present invention, by using a method that is reversed from conventional laser marking, the characters that make up the mark stand out, making the mark easier to see, and the line width of the characters making up the mark is also increased. This makes it easier to judge characters.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

Fig. 1 is a plan view showing one embodiment of the present invention;
1-1 line sectional view and FIG. 3 are perspective views of a semiconductor plastic package showing one embodiment of the present invention.

The pan cage 1 is made by fixing a semiconductor element onto a tab of a lead frame, wire-bonding the electrodes of the element and inner leads of the lead frame, and then molding the lead frame with a resin using a transfer mold. Three outer leads are pulled out.

The semiconductor element (chip) is made of, for example, a silicon single crystal substrate, and a large number of circuit elements are formed within the chip using a well-known technique to provide one circuit function. Specific examples of the circuit elements include, for example, MOS transistors, and these circuit elements form circuit functions such as a logic circuit and a memory.

The size of the package 1 is, for example, 1.25 to 1.5
It is said to be an ultra-compact size with a nm limit of 2.0 to 2.9 nm. A laser mark is formed on the upper surface of the molded body 2 as shown in the illustrated example.

In this example, the English letters L and C are used as marks.

The mold surface is not irradiated with laser light to the outer frame portion 4, the mark portion 5 composed of the above English text, and the connecting portion 6 connecting the mark portion 5 and the outer frame 4. part 7 and the part 7 to be rimmed by laser beam irradiation.

As shown in the second Gosho map, the part 5 that becomes the mark composed of the English letters Li2 and C protrudes from the part 7 obtained by trimming the mold surface, and the part 5 with the English letters is not raised. can be set.

FIG. 4 shows another embodiment of the present invention, in which English characters and C characters are used.
I) External? "f' shows an example in which the laser mark was marked in the same manner as in the above embodiment except that each was trimmed into a circular shape.

In the conventional example, when forming a mark consisting of an English letter and a C as described above, the mold surface is trimmed to form L and C by laser beam irradiation. In other words, L and C concave,
Compared to the black mark of the resin molded body (mirror direction), the concave part is brown (matte finish), and the brown part is extremely small compared to the black part, resulting in poor contrast and L The letters C and C are quite easy to read.

On the other hand, in the present invention, the English character part 5 is convex, is configured in black, and stands out from the trimmed part (brown) 7, and the black part 5 is in the large brown part 7.
Because of the presence of these L
The letters 5 and 5 are legible. Furthermore, by adjusting the thickness of the portion 7 to be trimmed, the character portion 5
The size of the mark 5 can also be increased, so that the mark 5 can be easily seen and the mark 5 can be easily read.

The method of the present invention is particularly effective when the mold surface is extremely small for an ultra-small package, and marks such as letters must be made extremely small. This is an extremely useful technique when marking packages, as it prevents the visibility of marks due to clouding after liquid hosing. Even if the mold surface of the mold body 2 is glossy due to the transfer mold during resin molding, the mark 5 can be easily read.

Although the invention has been specifically explained above based on the embodiments of the invention made by the present inventor, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from the gist thereof. Also u~).

For example, in the above embodiment, the mark is formed only on the upper surface of the mold surface of the package, but the mark may be formed in other ways, such as forming only on the lower surface on the opposite side or including the lower surface of the mold. You can also add .

In the above explanation, the invention made by the present inventor has been mainly applied to the marking method of semiconductor devices, which is the background and the field of application in which the present inventor has indulged. The present invention can also be applied to parts and devices.

〔Effect of the invention〕

The following is a brief explanation of the effects obtained by typical inventions disclosed in this application.

According to the present invention, it is possible to overcome the difficulty in deciphering the marks of the laser mark method, which improves the drawbacks of the ink mark method, and provides an excellent marking method. be.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a perspective view of a semiconductor package shown in FIG. FIG. 7 is a plan view showing another embodiment of the present invention. 1...Package, 2...Mold body, 3...Lead diagram diagram

Claims (1)

[Claims] 1. In a method of marking a package by irradiating a laser beam onto the mold surface of a resin-molded electronic component to create a mark consisting of letters, etc., the part that will become the mark is not irradiated with the laser light, and the mark is formed. A laser marking method characterized in that the mold surface other than the part is trimmed by irradiating a laser beam to make the part that will become the mark protrude.