CN104384647B - For the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit - Google Patents

Abstract

The invention discloses a welding method for an ultra-small Schottky diode and a quartz substrate thin film circuit. Point soldering flux on the soldering pad of the circuit, and the soldering flux is used to stick the indium-lead soldering ball to be placed on the soldering pad of the quartz thin-film circuit; place the indium-lead soldering ball on the soldering pad of the quartz substrate thin-film circuit, and place The indium-lead solder balls are flattened; the ultra-small Schottky diodes are placed on the flattened indium-lead solder balls; the ultra-small Schottky diodes are fused with the solder pads of the quartz substrate thin-film circuit by heating the indium-lead solder balls through the heating stage Solder together; inspect the solder joints formed during fusion welding, and conduct electrical tests on the welding of ultra-small Schottky diodes and quartz substrate thin-film circuits. The method of the invention is simple, low in cost and strong in feasibility, and effectively solves the problem that only expensive flip-chip welding equipment can be used to weld ultra-small Schottky diodes.

Description

A welding method for ultra-small Schottky diodes and thin-film circuits on quartz substrates

technical field

The invention relates to a method for coincident welding of an ultra-small Schottky diode and a thin film circuit of a quartz substrate.

Background technique

The THz frequency band is located between microwave and infrared, and is a very important cross-frontier field. Due to its characteristics of wide frequency band, narrow pulse, strong penetration and good confidentiality, it is widely used in the fields of radar, RCS characteristic scaling test, radio astronomy, satellite communication, safety testing and non-destructive testing, etc., and has very important economic and social significance.

Terahertz components based on ultra-thin microstrips have been widely used due to their advantages of high integration, easy production and high reliability. However, a key process problem to be solved in the specific implementation is how to realize ultra-thin quartz substrates. Precision microassembly of thin-film circuits. Ultra-thin quartz substrate thin-film circuit precision micro-assembly technology is to realize the assembly of micron-level installation errors through manual or mechanical methods. Both the Schottky diode and the quartz substrate need to be assembled into the metal cavity through a micro-assembly process, which mainly includes two steps: one is the bonding of the thin film circuit of the quartz substrate to the conductive adhesive of the metal cavity; the other is the bonding of the Schottky diode with the metal cavity Soldering interconnection of thin film circuits on quartz substrates. Among them, the installation of Schottky diode is the key point of the whole process, which directly determines whether the terahertz components can work normally, and a little carelessness in the installation process will cause the diode to short circuit. The length of Schottky diodes is on the order of microns (the size is generally 300 μm × 100 μm), and the thickness is generally 50 μm or even thinner, and the thickness, pad width and pad spacing of the quartz substrate thin film circuit are all on the order of 50 μm. Conventional methods are used for welding, so the welding of Schottky diodes on the quartz substrate thin-film circuit restricts the development of the entire terahertz component.

Regarding the welding method of ultra-small Schottky diodes and quartz substrate thin-film circuits, patent application number 201010135506.5 discloses that a conductive adhesive film with double-sided stickiness is pasted on the back of the diode to realize the packaging of the diode and the lead frame; Patent application No. 200710307524.5 discloses a package in which a gold bump is planted on the pad of the diode to realize the interconnection between the diode and the lead frame pins.

Patent application number 201010135506.5 discloses that a conductive adhesive film with double-sided adhesiveness is pasted on the back of the diode to realize the packaging of the diode and the lead frame. This method is also commonly used in the packaging of Schottky diodes and substrates. However, the disadvantage of this method is that due to the use of a conductive film doped with metal elements during packaging, the diode is much worse than the method of brazing packaging in terms of heat dissipation and electrical characteristics after packaging; on the other hand, due to The bonding pad of the Schottky diode is too small, it is difficult to cut the conductive adhesive film with the same size as the bonding pad, and it is easy to cause a short circuit of the diode.

In addition, patent application No. 200710307524.5 discloses a package in which a gold bump is planted on the pad of the diode to realize the interconnection between the diode and the lead frame pins. Although this method allows the device to have good thermal conductivity and electrical performance, the gold bump The preparation of the bumps requires expensive equipment, and the soldering of the gold bumps to the lead frame is not easy to handle.

Therefore, it is necessary to develop a new simple method for welding ultra-small Schottky diodes and quartz substrate thin-film circuits, which can not only realize the defect-free welding of ultra-small Schottky diodes and quartz substrate thin-film circuits, but also requires Solve the problem of difficult operation in the welding process, and have high applicability.

Contents of the invention

In order to solve the deficiencies in the prior art, the present invention discloses a method for coincident welding of ultra-small Schottky diodes and quartz substrate thin-film circuits. The purpose of the present invention is to provide a simple method to realize the The welding of the Schottky diode and the thin-film circuit of the quartz substrate solves the problem that the current ultra-small Schottky diode and the thin-film circuit of the quartz substrate are not easy to weld.

To achieve the above object, the specific scheme of the present invention is as follows:

A welding method for an ultra-small Schottky diode and a quartz substrate thin-film circuit, comprising the following steps:

Step 1: Select 2-4 indium-lead solder beads in the indium-lead solder paste and melt them into an indium-lead solder ball on a DC heating table. The area matches;

Step 2: Apply no-clean flux on the pad of the quartz substrate thin film circuit;

Step 3: Put the indium-lead soldering ball fused in step 1 on the welding pad of the quartz substrate thin-film circuit with flux on the middle point of step 2, and flatten the indium-lead soldering ball;

Step 4: Place the ultra-small Schottky diode on the flattened indium-lead solder ball;

Step 5: Heating indium-lead solder balls through a DC heating table to weld the ultra-small Schottky diode and the pad of the quartz substrate thin film circuit together;

Step 6: inspect the solder joints formed during the fusion welding in step 5, and conduct an electrical test on the welding of the ultra-small Schottky diode and the thin-film circuit of the quartz substrate.

In said step one, the number of tin beads is selected to match the area of the pad of the ultra-small Schottky diode, specifically referring to the fact that the indium-lead solder balls formed by the melting of the tin beads should be able to occupy 30% of the pad of the ultra-small Schottky diode. /4.

In the process of forming indium-lead solder balls from tin beads in the first step, the temperature of the heating stage is required to be 210° C. to 220° C., and the formed indium-lead solder balls are removed from the heating stage within 5 seconds.

The diameter of the indium-lead solder ball in the step 1 is 30 μm to 50 μm;

In said step 2, spot flux on the welding pad of the quartz substrate thin-film circuit, specifically, use a needle tip to spot a drop of flux on the welding pad of the quartz substrate thin-film circuit.

In the described step 3, the indium-lead soldering balls melted into are placed on the soldering pads of the quartz substrate film circuit microstrip sheet by tweezers, and the indium-lead soldering balls are flattened with tweezers; the indium-lead soldering balls are flattened for Ensure that the ultra-small Schottky diodes are in good contact with the thin-film circuit on the quartz substrate.

The fusion welding in the step 5 requires the welding temperature to be 230° C. to 245° C., and the welding time is within 5 seconds to remove the quartz substrate thin-film circuit microstrip that has welded the ultra-small Schottky diode.

In said step 6, firstly, X-ray detection will be carried out on the solder joints to observe whether there are void defects in the solder joints; secondly, when performing electrical performance testing, because the pads of the ultra-small Schottky diodes are very small, it is necessary to test the solder joints. Solder 18mm gold wire on the probe and then test the electrical characteristics of the ultra-small Schottky diode.

The ultra-small Schottky diode is mainly used in a terahertz circuit realizing terahertz microwave characteristics.

Beneficial effects of the present invention:

The purpose of the invention is to effectively solve the problem that ultra-small Schottky diodes are not easy to be welded to quartz substrate film circuits by using the method of indium-lead solder paste melting balls. Put the indium-lead solder balls formed by melting the heating table on the pads of the quartz thin film circuit, then place the ultra-small Schottky diodes on the solder balls, and finally heat the heating table to realize the welding of the two, and solve the problem The problem that the ultra-small Schottky diode and the thin-film circuit of the quartz substrate are not easy to weld. Due to the simple melting ball method to achieve welding, it avoids the use of expensive equipment to complete the flip-chip welding of the two, reduces the cost, and improves the yield of ultra-small Schottky diode welding, and this method has universal applicability.

The method of melting balls of indium-lead solder paste effectively solves the problem that ultra-thin chips are not easy to solder, with low cost and strong feasibility; indium-lead solder balls are directly formed by heating solder beads in indium-lead solder paste, and the method is simple ,Wide range of applications.

Description of drawings

Fig. 1 is a kind of method flowchart that is used for ultra-small Schottky diode and quartz substrate film circuit anastomosis welding provided by the present invention;

FIG. 2 is a schematic diagram of a method for coincident welding of an ultra-small Schottky diode and a quartz substrate thin-film circuit provided by the present invention.

detailed description:

The present invention is described in detail below in conjunction with accompanying drawing:

In order to make the object, technical solution and advantages of the present invention clearer, the method for welding the ultra-small Schottky diode and the quartz substrate thin film circuit of the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

As shown in Fig. 1, a kind of method that is used for super-small Schottky diode and quartz substrate thin-film circuit conformal welding, this method comprises the following steps: first select 4-5 tin beads in the indium-lead solder paste on the heating stage Melt into a small indium-lead solder ball, and then put flux on the pad of the quartz substrate thin-film circuit, the purpose is to stick the indium-lead solder ball that will be placed on the pad of the quartz thin-film circuit through the flux, At the same time, place the fused indium lead solder ball on the pad of the microstrip sheet through tweezers, and use the tweezers to gently flatten the indium lead solder ball; secondly, place the ultra-small Schottky diode on the flat indium lead solder ball On the solder ball, the Schottky diode and the quartz substrate film are welded together by heating; that is, first adjust the temperature of the heating table to 230-240 degrees, and then put the quartz substrate with the solder ball on the heating table first Then put the Schottky diode back on the pad of the quartz substrate, and the melting of the solder ball will melt the two together. Finally, the solder joints are inspected, and the electrical test is carried out on the welding of the Schottky diode and the quartz film.

Among them, the heating temperature used to form indium-lead solder balls is 210°C-220°C, and the time is controlled at about 5S; the temperature used for welding ultra-small Schottky diodes and quartz thin film circuits is 230°C-245°C, and the welding time is controlled At about 5S, the schematic diagram of the entire welding process is shown in Figure 2.

Fig. 2 is a schematic diagram of welding process of an ultra-small Schottky diode and a thin-film circuit of a quartz substrate, wherein:

1 is to select 4-5 tin beads in the indium-lead solder paste and melt them into a small indium-lead solder ball on the heating table; it is required to determine the selection from the indium-lead solder paste according to the pad size of the ultra-small Schottky diode The number of tin beads, the indium-lead solder balls formed by tin beads must be able to occupy 3/4 of the pads of ultra-small Schottky diodes, and in the formation of indium-lead solder balls by tin beads, the temperature of the heating table is required to be at 210 ℃～220℃, the time is controlled at about 5S;

2 is the pad of the quartz thin film circuit;

3 In order to apply flux on the pad of the quartz substrate thin film circuit, it is required to use a needle tip to point a drop of flux on the pad of the quartz substrate thin film circuit;

4. To place the indium-lead solder balls on the pads of the quartz thin-film circuit with tweezers, it is required to use tweezers to flatten the indium-lead solder balls;

5. In order to solder the ultra-small Schottky diodes on the flat indium-lead solder balls through tweezers, the soldering temperature is required to be 230°C to 245°C, and the soldering time is controlled at about 5S.

To sum up, in the method for welding ultra-small Schottky diodes and quartz substrate thin-film circuits of the present invention, due to the method of forming indium-lead solder balls through solder beads in indium-lead solder paste to achieve alignment The coincident flip-chip welding of Tertky diodes and quartz substrate thin-film circuits is simple, low-cost, and highly feasible, and effectively solves the problem that only expensive flip-chip welding equipment can be used to weld ultra-small Schottky diodes. Wide range of applications.

Claims (7)

1., for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, comprise the following steps:

Step one: choosing 2-4 indium slicker solder pearl in indium lead welding cream and melt into an indium lead welding ball on DC heating platform, the quantity choosing indium slicker solder pearl to match with the area of the pad of extra small Schottky diode；

Step 2: no-clean scaling powder on putting on the pad of quartz substrate thin flm circuit；

Step 3: indium lead welding ball step one melted is placed on the pad of quartz substrate thin flm circuit of scaling powder on step 2 midpoint, and indium lead welding ball pier is put down；

Step 4: extra small Schottky diode is placed on the indium lead welding ball of pier graduation；

Step 5: heat indium lead welding ball by DC heating platform and the pad of extra small Schottky diode Yu quartz substrate thin flm circuit is welded together；

Step 6: the solder joint formed during to step 5 melting welding is tested, and the pad of extra small Schottky diode Yu quartz substrate thin flm circuit is carried out electrical testing；

The area choosing the quantity of indium slicker solder pearl and the pad of extra small Schottky diode in described step one matches, and refers specifically to the indium lead welding ball that indium slicker solder pearl is melt into and wants to take the 3/4 of extra small Schottky diode pad；

In described step one, indium slicker solder pearl is formed in the process of indium lead welding ball, it is desirable to the temperature of warm table is at 210 DEG C～220 DEG C, and the time controls within 5S.

2. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, in described step one, the diameter of indium lead welding ball is at 30 μm～50 μm.

3. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, scaling powder on putting on the pad of quartz substrate thin flm circuit in described step 2, is specially employing needle point and puts a scaling powder on the pad of quartz substrate thin flm circuit.

4. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, described step 3 is placed on, by tweezers, the indium lead welding ball melted on the pad of quartz substrate thin flm circuit, and adopts tweezers that indium lead welding ball pier is put down.

5. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, requiring during melting welding in described step 5 that the temperature welded is at 230 DEG C～245 DEG C, the time of welding controls within 5S.

6. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, in described step 6, butt welding point carries out X-ray check, observes whether solder joint has cavity blemish.

7. as claimed in claim 1 for the identical welding method of extra small Schottky diode and quartz substrate thin flm circuit, it is characterized in that, in described step 6, when carrying out electrical performance testing, on the probe of test in soldering length be 18mm spun gold after the electrology characteristic of the extra small Schottky diode of re-test.