JP2013074218A - Imprint method to electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid damage due to burning of an element formed in an electronic component at the time of imprinting, and to avoid deterioration of a seal in the manufacturing process thereof.SOLUTION: In the imprint method to an electronic component, surface roughening is performed so as to form at least two kinds of rough surface 2x, 2y having different roughness on the rear surface of a piezoelectric wafer W on which electronic components 1 are formed collectively. Subsequently, predetermined information is imprinted, and the roughness of at least two kinds of different rough surface thus formed is identified by binary-coded identification processing.

Description

  The present invention relates to a method for marking electronic components such as surface acoustic wave devices (hereinafter referred to as SAW devices).

In the case of an electronic component, for example, a SAW device, comb-shaped electrodes (IDT electrodes) and wiring electrodes are formed on the main surface of a piezoelectric wafer made of quartz, LiTaO ₃ , LiNbO _3, etc., and then each SAW device is separated from the piezoelectric wafer. After being divided into individual pieces and mounting the pieces in a ceramic package and connecting the element package by wire bonding using metal wiring, or by providing bumps on the element wiring and connecting by flip chip mounting It was common to seal in a package.

  Nowadays, in order to further reduce the size and height of electronic components, a wafer level chip size package (abbreviated as WL-CSP) that performs sealing and electrode formation in the wafer manufacturing process is put into practical use. became.

  On the other hand, even if the electronic component is downsized, it is still necessary to display (mark) the name of the product and the notation (marking) such as the directionality of the IDT electrode on the back surface of the chip of the electronic component. Under such circumstances, there are a limited number of technologies for maintaining the low profile of electronic components and forming displays on electronic components at low cost, and conventional display technologies using lasers or inks are miniaturized electronic devices. Application to parts was becoming difficult.

In an electronic component, for example, a SAW device, an element pattern such as a comb-shaped electrode is formed on a main surface of a transparent piezoelectric wafer having a crystal structure with a metal thin film. For this reason, when a laser device such as YAG, CO ₂ or a green laser is used to directly mark (mark) characters, symbols, etc. on the back surface of the wafer, the laser beam is transmitted through the transparent wafer, and the main wafer An element formed on the surface, for example, an internal electrode may be burned to cause damage. Therefore, it is very difficult to directly mark the product number on the piezoelectric wafer with a laser.

  Moreover, even if a short wavelength green laser, excimer laser, or femtosecond laser is used for a crystalline wafer, a crack is generated in a portion irradiated with laser light, and the wafer is damaged. It was extremely difficult to stamp the display on the wafer.

  Furthermore, in the wafer level chip size package that completes all processes from the first process to the packaging process in units of wafers, as a method for marking electronic parts, ink transfer by rubber stamps, or no display at all, or For example, there is a method for identifying only the directionality of the surface wave of the SAW device. In this regard, the display content is simplified as much as possible. For example, in addition to means for displaying a directional mark on only one side of an electronic component, a method of displaying (stamping) a resin sheet on the back surface of the wafer There is.

  On the other hand, electronic components are becoming smaller and lower in profile, and in many cases, device formation, sealing, and terminal formation are performed consistently at the wafer level. For the reasons described above, direct marking is performed on the wafer. For this purpose, it is necessary to attach a resin sheet to the back surface of the wafer and stamp the resin portion, or to stamp using a non-transparent wafer, or to transfer the ink to the wafer.

  In addition, in the ink jet method, the ink dot size is large (for example, 60 μm), and this type method is not suitable for displaying characters because the dot size is too large for display on a small electronic component. .

  Furthermore, in an electronic component, for example, a SAW device, in general, vibration that leaks from the active surface (main surface) of the piezoelectric element to the back surface of the wafer is reflected on the back surface of the active element and deteriorates the characteristics of the SAW device. Even if the ink having the minute protrusions is finely applied, the surface energy is low and the ink easily spreads out, so that the ink may bleed on the printing surface and the displayed characters may be difficult to identify.

  On the other hand, it is possible to transfer high-viscosity ink to a wafer by a letterpress printing technique, but a letter size of about 0.3 mm square is the limit of letterpress printing, and the content to be displayed is changed. Each time, it was necessary to change the letterpress. Further, the contact printing method has a problem that the printing quality is not stable due to ink supply, plate wear, and the like.

  In addition, the surface of the electronic component (the back surface of the chip) is engraved, and after the ink is applied to the surface including the engraving, the particle size of the abrasive particles that spray the removal of the ink adhering to the outside of the engraved recess is larger than the width of the engraving. Then, there is a method in which the blast method is used to make a clear and non-disappearing seal. However, in this method, since the marking is still performed with the laser beam, the laser beam is transmitted through the chip, and there is a possibility that the element formed on the main surface of the chip is damaged.

  Furthermore, the above-described conventional marking method cannot sufficiently secure the marking that does not deteriorate due to acid, photoresist developer, various solvents, heat, etc. in the plating process used in the manufacturing process of the electronic component.

  In addition, there is a display function provided by spraying fine particles on the surface of the electronic component container by sandblasting and changing the surface reflectance of the information display part, for example, binarization processing. An image processing apparatus or the like is required.

JP 2007-250970 A JP 2008-244228 A JP 2009-017454 A Japanese Patent Application Laid-Open No. 61-228991 JP 2007-97038 A

  The problem to be solved by the present invention is to avoid damage caused by burning of elements of electronic components during stamping and deterioration of the stamp in the manufacturing process.

  In order to solve the above-described problems, the present invention performs rough surface processing so as to form a rough surface having two different roughnesses on the back surface of a wafer on which electronic components are collectively formed, and imprints predetermined information. It is characterized in that the roughness of the two types of rough surfaces formed is identified by binary digitization identification processing.

  In the present invention, the rough surface processing is performed by sandblasting.

  In the present invention, the rough surface processing is performed by jet scrubbing.

  Furthermore, the present invention is characterized in that the rough surface processing is performed by a photolithography technique.

  Still further, the rough surface processing is performed using a screen mask.

  In the present invention, the rough surface processing is performed using a metal mask.

  In the present invention, the rough surface processing is performed by adjusting an amount of digging down the back surface of the piezoelectric wafer.

  In the present invention, the predetermined information is a character, a symbol, a pattern, a direction, management information, and identification management information for identifying the electronic component.

  Damage due to burning of the elements of the electronic component at the time of marking is avoided, and the deterioration of the marking in the manufacturing process of the electronic component is eliminated.

The longitudinal cross-sectional view of the electronic component which implements the marking method to the electronic component of this invention, for example, a SAW device, is shown. It is a top view which shows the arrangement | sequence etc. of each electronic component at the time of implementing the marking method to the electronic component of this invention at a wafer level. 1 shows an embodiment of a method for marking an electronic component according to the present invention, wherein (a) is a plan view of an embodiment in which two types of rough surfaces are formed on the wafer surface by sandblasting, and (b) is a longitudinal section thereof. A plane view is shown. An example of marking characters, symbols, patterns, etc., on which two types of rough surfaces are formed on the wafer surface by photolithography technique is shown, (a) is a plan view thereof, and (b) is a longitudinal section thereof. Each side view is shown. The flowchart of the manufacturing process of the electronic component of this invention is shown.

  Embodiments of an electronic component to which the marking method of the present invention is applied and a method for marking the electronic component will be described below with reference to the accompanying drawings.

Embodiment of Electronic Component FIG. 1 shows a SAW device which is an embodiment of a piezoelectric component of the present invention.

As shown in FIG. 1, this SAW device 1 includes a piezoelectric substrate (wafer) 2 having a piezoelectric function formed on a piezoelectric substrate such as lithium tantalate (LiTaO ₃ ), lithium niobate (LiNbO ₃ ), or the like. An IDT electrode 3 made of an aluminum film formed on the main surface of the piezoelectric substrate 2 by sputtering or vapor deposition, and an opening at its upper end made of a photosensitive resin film and laminated on the main surface of the piezoelectric substrate 2 And a ceiling part 5 made of the same photosensitive resin film laminated on the upper end surface of the outer wall part 4, and the laminated outer wall part 4, ceiling part 5 and piezoelectric substrate 2 are laminated. A hollow portion C surrounding the IDT electrode 3 and the wiring electrode is formed between the main surface and the main surface.

  Further, as shown in FIG. 1, for example, at the four corners of the piezoelectric substrate 2, four electrode columns (electrode posts) 6 are formed by electrolytic plating in holes (via holes) formed in the sealing resin P. The upper end portion of the electrode column 6 is electrically connected to the wiring electrode formed on the main surface of the piezoelectric substrate 2, and the other end portion is electrically connected to the terminal electrode 7. Then, if necessary, solder ball electrodes 10 are fixed to the lower end portions of these through electrodes 7, and flux is supplied around them to external wiring electrodes (not shown) of the mounting board B (printed board). The solder ball electrode 10 is connected to each. Here, the reason why the solder ball electrode 10 is fixed to the lower end portion of the through electrode 7 is that the connection work to the mounting substrate P becomes extremely difficult when the pitch between the through electrodes 7 is reduced to, for example, about 200 μm. In order to modularize the element, when a customer performs a mounting operation on a printed circuit board, a solder ball having a diameter of about 150 μm is fixed to the lower end portion of the through electrode 7 in advance to constitute the solder ball electrode 10. . If the customer can connect the through electrode 7 directly to the mounting substrate B using solder paste, the solder ball electrode 10 need not be fixed.

  Here, the comb electrode 3 and the wiring electrode constitute a piezoelectric element, and the piezoelectric element can be applied to an element manufactured by FBAR, MEMS, etc. in addition to a surface acoustic wave (SAW) element.

  In particular, in the SAW device, which is an embodiment of an electronic component to which the marking method of the present invention is applied, the rough surface processing is performed on the back surface 2a of the substantially transparent piezoelectric wafer 2 shown in FIG. Marks are provided so that symbols and the like (for example, product type, lot number, surface wave directionality, date of manufacture) can be identified.

  The surface (active surface) 2b (active element forming surface such as comb-tooth electrode and wiring electrode) of the piezoelectric wafer 2 shown in FIG. 1 can be roughened to mark characters, symbols, etc. As shown by the symbol P in FIG. 1, the active surface is not suitable because it is not sealed from the outside because it is resin-sealed.

Example of Method for Stamping Electronic Components In the method for marking electronic components of the present invention, as shown in FIG. 2, for example, a collective piezoelectric substrate (wafer) W on which 100 piezoelectric components can be formed is manufactured as shown in FIG. As shown in the flowchart of the process, preparation is performed (process S1), and a film is formed on the main surface of the wafer W (process S2).

  Next, patterning is performed on the film formation surface formed on the main surface of the wafer to form active elements such as comb-teeth electrodes (IDT) and wiring / penetrating electrodes (step S3).

  Then, rough surface processing is performed to form two types of rough surfaces 2x and 2y (see FIG. 3 and FIG. 4) having different roughnesses on the back surface 2a of the wafer W (step S4), and then into individual pieces. Each piezoelectric component 1 is manufactured by dividing along a dicing line D shown in FIG. 2 with a dicing saw or the like (step 5).

  In particular, in an embodiment of the electronic component marking method of the present invention, a wafer level chip size package (abbreviated as WL-CSP) is used to attach a large number of electronic components to a piezoelectric wafer (collective piezoelectric substrate, hereinafter referred to as “wafer”). When forming in a lump, a predetermined rough surface processing (roughening) on the back surface 2a of the wafer is performed by dividing the roughness of the rough surface into two types of rough surfaces. Product directionality (for example, surface wave directionality), pattern, management information, and identification management information D are marked (marked), and these markings are visually checked with a magnifying glass or binary identification processing is performed by an image processing apparatus. Like that.

  As a first embodiment of the electronic component marking method of the present invention, as shown in FIG. 3A, the surface of the wafer (the upper surface of the electronic component (the back surface of the chip)) is obtained by using sandblast for the predetermined rough surface processing. The rough surface processing is performed so that at least two types of rough surfaces 2x and 2y of roughness A and roughness B are formed.

  In this case, the roughness A and B to be sandblasted is such that roughness A> roughness B or roughness B> roughness A, so that the propagation direction (direction) of SAW of an electronic component, for example, a SAW device can be determined. To. Here, the adjustment of the roughness of the rough surface to be sandblasted is performed by appropriately changing the count of the abrasive (particle) to be used (for example, appropriately selected from the range of # 800 to # 1000) to two or more types of counts, A sand blast surface of the wafer is covered with a dry film (for example, Odeil BF-440, manufactured by Tokyo Ohka Kogyo Co., Ltd.), and sand blasting is performed. The gloss (optical reflectivity) between the blast surface and a non-blast surface or a blast surface having a different roughness. ) Or the like, and the identification symbol (roughness A, B) automatically binarized using an image processing device to identify the propagation direction of the SAW (surface acoustic wave), or Even when a magnifying glass or the like is used, the identification symbol binarized visually is identified to identify the directionality. This identification method can also be applied to other marking methods described below.

  Moreover, it can replace with the rough surface process by the above-mentioned sand blasting, and can use the rough surface process by the jet scrub which inject | emits an alumina powder to a processed surface.

  Next, as a second embodiment of the electronic component marking method of the present invention, as shown in FIG. 4, a photolithographic technique is used for the predetermined rough surface processing, and characters, symbols, patterns, etc. are formed on the back surface 2a of the wafer. The seal is performed. That is, as in a normal photolithography technique, as shown in FIG. 4A, for example, a photoresist is applied to the back surface 2a of the wafer, and exposure, development, and etching are performed using a mask in which the numeral A123 is punched out. After that, the remaining photoresist is removed, and a number (A123) is exposed and printed on the back surface 2a of the wafer, which is used for identification of electronic components. According to the photolithography technique, it is possible to mark minute characters and symbols.

  Alternatively, the surface of the wafer may be roughened by sandblasting using a screen mask or metal mask having an opening, and characters, symbols, patterns, etc. may be imprinted on the surface of the wafer corresponding to the opening.

  Further, the rough surface processing may be performed by adjusting the digging amount of the rough surface formed on the surface of the wafer, and characters, symbols, patterns, etc. may be stamped on the surface of the wafer.

  Further, in the method for marking electronic parts according to the present invention, since the parts to be the individual electronic parts are collectively stamped on the wafer as the collective substrate, the dimensions and arrangement of the electronic parts in the final form as shown in FIG. Then, as shown in FIG. 5, each electronic component is cut out with a dicing saw or the like and separated into individual pieces.

1 Electronic components (SAW devices)
2 Piezoelectric wafer 3 Comb electrode (IDT)
4 Wiring electrode 5 Terminal electrode 6 Through electrode 8 Outer wall 9 Ceiling wall B Mounting substrate C Hollow part D Dicing line P Resin sealing part W Piezoelectric wafer (collective piezoelectric substrate)

Claims (8)

  Electronic parts are collectively formed. Roughening is performed so as to form two types of rough surfaces on the back surface of the wafer, and predetermined information is imprinted, and at least two types of rough surfaces formed are roughened. A method for marking electronic parts, characterized in that identification is performed by binary digitization identification processing.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed by sandblasting.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed by jet scrubbing.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed by a photolithography technique.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed using a screen mask.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed using a metal mask.   The method for marking an electronic component according to claim 1, wherein the rough surface processing is performed by adjusting an amount of digging of the back surface of the piezoelectric wafer.   8. The method of marking electronic parts according to claim 1, wherein the predetermined information displays characters, symbols, patterns, directions, management information, and identification management information for identifying the electronic parts.

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