JP4839947B2 - Board desoldering equipment - Google Patents

Description

The present invention relates to a substrate desoldering apparatus for removing solder from a defective solder substrate.

  In recent years, due to the demand for development of highly functional semiconductors, the density of package substrates on which semiconductor chips are mounted has been increasing. The solder bumps on which flip chips are mounted are also becoming finer and higher in density, and the distance between the bumps is becoming as narrow as 150 μm. For this reason, as shown in FIGS. 3A and 3B, defects such as a bridge 15 between the solder bumps 13 of the substrate 11 and a shortage of solder 17 frequently occur.

  Conventionally, as shown in FIG. 4, the substrate on which such a solder failure has occurred is heated in the oxygen-free atmosphere such as nitrogen gas by heating the substrate 11 with the heater 19 to melt the solder, and with the brush 21 with the substrate 11. The solder was removed by rubbing the surface. After that, repair (removing the solder bumps and returning to a state where reprinting is possible) is performed to perform reprinting.

  However, in recent years, the pitch between the bumps 13 tends to be narrowed with the miniaturization, and it is difficult to eliminate the bridge 15 because the stretched solder remains even if the solder is scraped.

  On the other hand, recently, a PALAP (Patterned prepreg Lay up Process) substrate has been developed as a high-density substrate. This PALAP substrate is obtained by laminating a large number of thermoplastic resin sheets whose surfaces are patterned and via holes are filled with a metal paste, press-molded at once, and simultaneously connecting and bonding. In this PALAP substrate, since the land on the surface layer is small, a resin layer is formed on the outer periphery of the land to prevent the land from peeling off. Therefore, the land 23 is located on the bottom surface of the recess 25 surrounded by the resin layer, and the solder bump 13 is mounted on the land 23.

  For this reason, in the PALAP substrate, the work surface has many irregularities and it is difficult to remove the solder, and the molten solder may flow into the dent of the land, and the conventional method cannot sufficiently remove the solder. There was a problem.

  There is also a method of sucking out solder with a solder suction device, but this has the following problems. That is, the land made of copper foil is provided with an undercoat in order to improve the bondability between the copper foil and the solder bump. However, when the solder in the recess is sucked with a suction device, the solder including the undercoat is sucked, and there is a problem that reprinting cannot be performed on the repaired substrate.

The present invention has as its object to solve the above-mentioned problems, and provides a board solder removal apparatus that can sufficiently remove defective solder even in a high-density board.

  In order to solve the above-mentioned problem, in a method for removing solder from a substrate in which solder on a defective solder substrate (S) is melted and removed, the defective solder substrate (S) is heated in a liquid state at a temperature exceeding the melting point of the solder (L ) And a step of rubbing the surface of the defective solder substrate (S) with a brush and scraping off the defective solder, and melting the solder of the defective solder substrate (S) A device for removing solder from a substrate to be removed, the solder processing tank (33) storing a heat medium (L) in a liquid state at a temperature exceeding the melting point of the solder, and the solder processing tank (33) The substrate transport device that is carried in and out of the solder and the solder that is heated and melted by the heat medium (L) by rubbing the surface of the defective solder substrate (S) immersed in the heat medium (L) in the solder treatment tank (33) Scrape It can be employed means and a brush (45).

  According to this means, even the solder printed at a fine pitch on the substrate surface having fine irregularities can be reliably removed. Further, since the substrate is immersed in the liquid, the temperature distribution over the entire substrate can be made uniform, and temperature stress can be reduced. Furthermore, since heat melting is performed in the liquid, solidification can be prevented and removal can be smoothly performed even when the solder is separated from the substrate. In addition, since the heat medium covers the solder surface after the solder is removed, re-welding of the solder can be prevented. Furthermore, since the solder melted by heating with the heat medium is removed, the solder can be stirred and removed by simply pressing the brush against the substrate, so that mechanical stress on the substrate surface can be minimized.

  In order to solve the above-mentioned problem, it is possible to employ a means further comprising a step of receiving the solder scraped off by the brush (45) in a solder recovery container (49) provided below the substrate. (33) A means further provided with a solder recovery container (49) for receiving solder scraped off from a defective solder substrate can be employed. Therefore, the fine molten solder scraped off from the defective solder substrate can be collected, and can be gradually aggregated and collected by collecting them in one place.

  In order to solve the above-mentioned problems, the solder processing tank (33) can employ means having a heater (39) in the lower part thereof. Therefore, the heat medium in the solder processing tank can be easily heated, and the solder can be efficiently removed.

  In order to solve the above problem, the heat treatment medium (L) stored in the solder treatment tank (33) is continuously formed with the solder treatment tank (33) to cool the vapor of the heat medium (L). A means further provided with a cooling chamber (41) for cooling residual solder on the substrate surface in a non-oxidizing atmosphere can be adopted, and the cooling chamber (41) is provided with a cooling means (43) on the outer periphery thereof. Can be adopted. Therefore, the substrate that has been carried in can be preheated and thermal shock to the substrate can be mitigated.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 shows a substrate solder removal apparatus 31 according to an embodiment of the present invention. The substrate desoldering device 31 has a bottomed cylindrical solder processing tank 33, and a lid 35 for closing the solder processing tank 33 is provided on the solder processing tank 33.

  In the solder processing tank 33, a repair chamber 37 for storing a heat medium L such as galten is formed in the lower half portion 33a. A heater 39 is provided below the repair chamber 37 of the solder processing tank 33 so that the heat medium L in the repair chamber 37 is heated to a predetermined temperature equal to or higher than the melting point of the solder. Then, the solder on the substrate is melted by immersing the substrate in the heat medium L heated above the melting point of the solder in the repair chamber 37.

  Inside the upper half 33b of the solder processing tank 33, a cooling chamber 41 for accommodating the steam G from the heat medium L is formed, and a heat exchanger 43 in which a coolant circulates on the outer periphery of the upper half 33b. Is provided. And the vapor | steam G of the heat medium of the cooling chamber 37 is cooled, aggregated, and collect | recovered.

  The solder removal device 31 includes a substrate transfer device (not shown) that moves a defective solder substrate S between an external position P1 of the solder processing bath 33, a position P2 in the cooling chamber 37, and a position P3 in the repair chamber 37. ) Is provided.

  The solder removal apparatus 31 includes a brush 45 that rubs the surface of the substrate S to remove the solder from the substrate when the defective solder substrate S is at the position P3 in the repair chamber 37, and a brush that holds the brush 45. A holding body 47 is provided, and a brush driving device (not shown) for moving the brush 45 vertically and horizontally with respect to the substrate surface is further provided. Here, this brush 45 employs a felt-like repair brush obtained by solidifying 8 μm stainless steel metal fibers of NASRON (registered trademark of Nippon Seisen Co., Ltd.) in order to cope with the solder that has entered the recess. Accordingly, it is possible to deal with unevenness on the substrate surface and to remove fine solder. Then, the solder on the substrate S that has been transported to the repair chamber 37 by the substrate transport device is heated and melted by the heat medium L, and is scraped off by the brush 45.

  A solder tray 49 is provided on the bottom surface of the solder processing tank 33 to accommodate the solder that has been scraped off from the substrate S by the brush 45.

  The outer periphery of the solder processing tank 33 and the heater 39 is covered with a heat insulating material 51. In addition, the temperature of each position inside the solder processing tank 33 is easily set, and heat is not leaked to the outside, so that energy efficiency is improved.

  A method of removing the solder of the PALAP substrate S in which the solder failure has occurred using the solder removing apparatus 31 configured as described above will be described.

  First, the substrate S is held by a substrate transfer device (not shown), moved from the position P1 to the position P2, and carried into the cooling chamber 41 of the solder processing tank 33.

  Since this cooling chamber 41 is filled with the low boiling point component of the evaporated heat medium, it is maintained at a temperature of 150 ° C. to 200 ° C., and the evaporated component of the heat medium is cooled and refluxed by the heat exchanger. The board | substrate S carried in here is pre-heated to the solder melting | fusing point vicinity so that a thermal shock may be relieved.

  Next, the substrate S is moved from the position P2 in the cooling tank 41 to the position P3 in the repair tank 37 and immersed in the heat medium L. The heat medium L is heated to a melting point of 250 ° C. of solder, for example, and the solder on the substrate is melted.

  Here, since the molten solder is in a liquid heat medium, it is easy to disperse into fine particles in the heat medium due to the surface tension of the solder and the surface tension of the heat medium. Can be removed. Moreover, since the solder is dispersed into fine particles in the heat medium, re-condensation of the solder can be prevented.

  Next, in this state, as shown in FIG. 2, the surface of the substrate S is rubbed with a felt-like brush 45 in which fine stainless steel fibers are hardened. In this case, the substrate is fixed and the brush is moved, but conversely, the brush may be fixed and the substrate may be moved. This makes it possible to disperse the solder that has entered the irregularities and depressions of the substrate into fine particles and easily remove them. In particular, in the case of the PALAP substrate S, the land Sc made of copper foil is formed on the bottom surface of the recess Sb that is recessed by about 50 μm from the substrate surface Sa, so that fine solder 45 can be used to remove the solder finely. It is. In this case, the land surface is provided with an undercoating to ensure the bondability between the copper foil and the bump solder, but it is necessary to prevent the undercoating from being removed. . For this reason, normally, the solder is removed to such an extent that the bump solder does not come out of the substrate surface.

  In this way, the solder 61 removed from the substrate S falls because it has a higher specific gravity than the heat medium, and is accommodated in a solder tray 49 provided below. In addition, the dispersed solder fine particles can be gathered together in one place, so that the solder can be collected easily.

Next, after the surface of the substrate S is rubbed vertically and horizontally by the brush 45 a predetermined number of times, the substrate S is raised by a substrate transfer device (not shown) and raised to a position P <b> 2 in the cooling chamber 41 . The solder on the land surface layer is solidified in the cooling chamber 41 in a smooth state, and then the substrate S is taken out from the cooling chamber 41 to complete the repair.

  As described above, in the solder removal apparatus 31 and the solder removal method, the solder processing tank 33 in which the heat medium L in a liquid state is stored at a temperature exceeding the melting point of the solder, and the solder defective substrate S are stored in the solder processing tank 33. A substrate transfer device that carries in and out and a brush 45 that scrapes off the solder overheated by the heat medium L by rubbing the surface of the defective solder substrate S immersed in the heat medium L in the solder treatment tank 33 are provided. Therefore, even the solder bumps printed at a fine pitch on the surface of the substrate having fine irregularities can be surely removed. Further, since the substrate is immersed in the liquid, the temperature distribution over the entire substrate can be made uniform, and therefore the temperature stress on the substrate can be reduced as compared with the case of local heating. Furthermore, since heat melting is performed in the liquid, the molten state can be maintained without being cooled even when the solder is separated from the substrate, and therefore, the solidification of the solder can be prevented and the removal can be performed smoothly. In addition, since the heat medium covers the solder surface after the solder is removed, re-welding of the solder can be prevented. Furthermore, since the solder melted by heating with the heat medium is removed, the solder can be stirred and removed by simply pressing the brush against the substrate, so that mechanical stress on the substrate surface can be minimized.

  In general, when solder is melted in an oxidizing atmosphere, it becomes an oxide and cannot be melted. However, in this solder removal apparatus and method, the temperature is raised in a heat medium in a non-oxidizing atmosphere and the solder is melted. Therefore, it is possible to prevent the solder from being oxidized and to maintain the molten state of the solder. Therefore, it is possible to easily collect and collect expensive solder. Further, since the solder is removed in a non-oxidizing atmosphere, an auxiliary device for supplying an inert gas such as N2 is not required for preventing the oxidation of the copper foil of the land after the solder is removed, and thus the cost can be reduced. .

Further, a cooling chamber 41 in which the vapor of the heat medium is maintained at a temperature of 150 ° C. to 200 ° C. is formed continuously above the heat medium stored in the solder treatment tank 33. The substrate that has been carried in can be preheated, and thus the thermal shock to the substrate can be mitigated.

  Further, since the repair chamber 37 and the cooling chamber 41 for storing the heat medium are formed in the solder processing tank 33, the entire apparatus can be made simple and compact.

  In the above embodiment, PALAP is given as an example of a substrate to be processed. However, the present invention is not limited to this, and the present invention can of course be applied to any substrate.

The schematic sectional drawing which shows the solder removal apparatus which is embodiment of this invention. The enlarged view of the part shown with the code | symbol A in FIG. It is a figure which shows a solder defect board | substrate, Comprising: (a) is the top view, (b) is the front view. The figure which shows the conventional solder removal method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 31 Solder removal apparatus 33 Solder processing tank 37 Repair chamber 39 Heater 41 Cooling chamber 43 Heat exchanger 45 Brush 49 Solder tray

Claims (4)

A solder removal apparatus for a substrate that melts and removes solder from a defective solder substrate (S),
A solder processing tank (33) storing a heat medium (L) in a liquid state at a temperature exceeding the melting point of the solder;
A substrate transfer device for transferring the solder defective substrate (S) into and out of the solder processing tank (33);
A brush that scrapes off the solder heated and melted by the heat medium (L) by rubbing the surface of the defective solder substrate (S) immersed in the heat medium (L) in the solder treatment tank (33). 45), and
Above the heat medium (L) stored in the solder processing tank (33), it is formed continuously with the solder processing tank (33) to cool the vapor of the heat medium (L) and A cooling chamber (41) for cooling the residual solder in a non-oxidizing atmosphere;
The substrate desoldering apparatus, wherein the cooling chamber is maintained at a temperature of 150 ° C. to 200 ° C. for relaxing a thermal shock to the defective solder substrate.   The said solder processing tank (33) has a heater (39) in the lower part, The solder removal apparatus of the board | substrate of Claim 1 characterized by the above-mentioned.   The board according to claim 1 or 2, further comprising a solder recovery container (49) provided in a lower part of the solder processing tank (33) for receiving solder scraped off from the defective solder board. Desoldering device.   The said soldering chamber (41) is provided with the cooling means (43) in the outer periphery, The solder removal apparatus of the board | substrate of Claim 1 characterized by the above-mentioned.

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