CN102990183A - Method for transferring paste soldering flux in process of repairing ball grid array (BGA) device - Google Patents

Abstract

The invention belongs to technologies of repairing ball grid array (BGA) devices, particularly relates to a method for transferring paste soldering flux in a process of repairing a BGA device and aims to provide a process for accurately controlling the height of paste soldering flux coated on the surface of a solder ball in the process of repairing the BGA device so as to prevent scraped BGA devices or printed boards caused by inappropriate soldering of the BGA solder ball. The method includes the steps that (1) the actual height H of the solder ball is determined according to the diameter of the solder ball of the repaired BGA device; (2) a square flat-bottomed container is used to contain the soldering flux; (3) the square flat-bottomed container is placed on a component picking up pallet of a repairing working table; and (4) one side of the solder ball of the BGA device is immersed in a mold of the paste soldering flux, a picking up suction nozzle is used to enable the solder ball of the BGA device to contact with a bottom mold of the mold of the paste soldering flux, and the work for coating the soldering flux on the BGA device is finished. When the infiltrative height of the paste soldering flux accounts for 45% to 55% of the actual height of the solder ball, the soldering quality is optimal. By means of the method, the coating height of the paste soldering flux is accurately controlled in the process of transferring the soldering paste, and the infiltrative height of the paste soldering flux is in a range from 45% to 55%H, so that the repairing qualities of the BGA device can be guaranteed.

Description

Shift the method for paste soldering flux in a kind of BGA device rework process

Technical field

The invention belongs to BGA device Rework Technics, the control of the paste soldering flux consumption when specifically being applied to BGA device maintenance in the electric dress connection process and height.

Background technology

Along with the needs of miniaturization of electronic products, highly integrated development, the application of high integration BGA device is increasingly extensive.BGA device integrated level is high, and solder joint is many and intensive, mostly is core devices and expensive.For guaranteeing product quality, in electric dress connection production process, need such device is reprocessed.

At present when BGA reprocesses, the normal employing directly carried out in the way of the printed board pad liquid scaling powder of coating or solder(ing) paste, because BGA reprocesses the existing element of periphery in the printed board, therefore need to customize the transfer that little web plate carries out solder(ing) paste and liquid scaling powder according to arrangement of elements on the plate, there is the problem that operation easier is large, success rate is low, simultaneously, usually cause scaling powder deficiency in the welding because liquid scaling powder is greatly mobile, cause the problem of reprocessing rear solder joint voidage height or rosin joint to happen occasionally.

For reduce the welding after solder joint the voidage rate and guarantee welding quality, reach simultaneously and improve the purpose of reprocessing success rate and reducing operation easier, can adopt immobilising paste soldering flux to reprocess, when the paste soldering flux height that applies when the soldered ball surface is spent and is hanged down, voidage height even the rosin joint of soldered ball; When paste soldering flux applies excessive height, then be prone to the postwelding solder joint and connect weldering or rework equipments and the situation such as can't pick up, therefore, what reprocess middle most critical is to need control reprocess the height of the paste soldering flux that device soldered ball surface applies.

Summary of the invention

The purpose of this invention is to provide the process that soldered ball surface in a kind of accurate control BGA device rework process applies the paste soldering flux height, prevent from causing because the welding of BGA soldered ball is improper scrapping of BGA device or printed board.

The present invention is achieved in that the method that shifts paste soldering flux in a kind of BGA device rework process, wherein, comprises the steps:

Step 1. is confirmed the actual height H of soldered ball according to the soldered ball diameter of reprocessing the BGA device;

$H=\frac{1}{2}(D+\sqrt{D^2-d^2})---\left(1\right)$

Wherein, D is the diameter of soldered ball, and d is the diameter of pad;

Step 2. is used square flat container splendid attire scaling powder, and scaling powder thickness L satisfies following relational expression;

$L=\frac{1}{2}H-\frac{\mathrm{n\π}(H^{2}D-\frac{1}{6}{H}^3)}{8\mathrm{ab}}---\left(2\right)$

Wherein, H is the actual height of the described BGA soldered ball of formula (1), and n is the soldered ball quantity of reprocessing the BGA device, and D is the diameter of soldered ball, and a is the length of square container inwall, and b is the width of square container inwall;

Step 3. places square flat container on the component pick-up pallet of reclamation work platform;

Step 4. immerses BGA device soldered ball one side in the paste soldering flux mould, and till using when picking up suction nozzle the soldered ball of BGA device being touched the bed die of paste soldering flux mould, finishes the scaling powder of BGA device and smear work.

Shift the method for paste soldering flux in aforesaid a kind of BGA device rework process, wherein, the square container described in the step 2 comprises: housing, bed die, THICKNESS CONTROL mould and scraper plate; Housing is for having rectangular groove, and the above places the bed die with the equal-sized slab construction of groove floor; Place the THICKNESS CONTROL mould of square frame-shaped on the bed die, the thickness of THICKNESS CONTROL mould is L, and the length of THICKNESS CONTROL mould square hole is a, and the width of THICKNESS CONTROL mould square hole is b.

Advantage of the present invention is:

The height that infiltrates when paste soldering flux account for the soldered ball actual height 45%～55% the time, welding quality is optimum.The present invention mainly passes through accurately to control the coating height of paste soldering flux in the soldering paste transfer process, highly is in 45%～55%H interval so that paste soldering flux infiltrates, and guarantees the quality of reprocessing of BGA device.

Description of drawings

Fig. 1 is the structure of container schematic diagram that takes up scaling powder;

Fig. 2 takes up the process schematic diagram that takes up scaling powder in the container of scaling powder;

System architecture schematic diagram when Fig. 3 is BGA device soldered ball immersion scaling powder.

Wherein, 1 is housing, and 2 is bed die, and 3 is thickness mode, and 4 is scraper plate.

The specific embodiment

The present invention is described further below in conjunction with the drawings and specific embodiments:

Shift the method for paste soldering flux in a kind of BGA device rework process, comprise the steps:

1. according to the soldered ball diameter of reprocessing the BGA device, confirm the actual height H of soldered ball.The diameter of the diameter of soldered ball and pad is directly related on the actual height H of soldered ball and the BGA device, and the actual height H of soldered ball can calculate by following relational expression (1).

$H=\frac{1}{2}(D+\sqrt{D^2-d^2})---\left(1\right)$

Wherein, D is the diameter of soldered ball, and d is the diameter of pad.Pad typically have a diameter from 75%～85% of soldered ball diameter.

2. use square flat container to take up scaling powder, thickness L satisfies following relational expression.

$L=\frac{1}{2}H-\frac{\mathrm{n\π}(H^{2}D-\frac{1}{6}{H}^3)}{8\mathrm{ab}}---\left(2\right)$

Wherein, H is the actual height of the described BGA soldered ball of formula (1), and n is the soldered ball quantity of reprocessing the BGA device, and D is the diameter of soldered ball, and a is the length of square container inwall, and b is the width of square container inwall.

In the present embodiment, use the described mould splendid attire of Fig. 1 paste soldering flux, mould is made of housing, bed die, THICKNESS CONTROL mould and scraper plate, uses scraper plate that the paste soldering flux on the mould is struck off, and sees Fig. 2.The thickness of THICKNESS CONTROL mould is L.Wherein thickness L satisfies following relational expression.

$L=\frac{1}{2}H-\frac{\mathrm{n\π}(H^{2}D-\frac{1}{6}{H}^3)}{8\mathrm{ab}}---\left(2\right)$

Wherein, H is the actual height of the described BGA soldered ball of formula (1), and n is the soldered ball quantity of reprocessing the BGA device, and D is the diameter of soldered ball, and a is the length of THICKNESS CONTROL mould square hole, and b is the width of THICKNESS CONTROL mould square hole.

3. the paste soldering flux mould is placed on the component pick-up pallet of reclamation work platform.(be among Fig. 22 position)

4. BGA device soldered ball one side is immersed in the paste soldering flux mould, and till using when picking up suction nozzle the soldered ball of BGA device being touched the bed die of paste soldering flux mould, see Fig. 3.

5. among Fig. 3, owing to BGA device soldered ball immerses in the scaling powder, the height of scaling powder rises, and paste soldering flux is the paste form, and the peripheral soldering paste that overflows can be ignored all around certainly, so the height of paste soldering flux becomes 1/2H from L.

6. use the vacuum slot of reclamation work platform to draw the BGA device, at this moment, the height that applies paste soldering flux on the BGA soldered ball is the described 1/2H of formula (1), namely all is coated with on the 1/2H surface highly once on the soldered ball and has been covered with paste soldering flux.

7. then use the rework equipments visual system that the BGA device that soldered ball scribbles paste soldering flux is mounted in the printed board, and then carry out reflow soldering and finish welding job.

Claims (2)

1. shift the method for paste soldering flux in the BGA device rework process, it is characterized in that: comprise the steps:

Step 1. is confirmed the actual height H of soldered ball according to the soldered ball diameter of reprocessing the BGA device;

$H=\frac{1}{2}(D+\sqrt{D^2-d^2})---\left(1\right)$

Wherein, D is the diameter of soldered ball, and d is the diameter of pad;

Step 2. is used square flat container splendid attire scaling powder, and scaling powder thickness L satisfies following relational expression;

$L=\frac{1}{2}H-\frac{\mathrm{n\π}(H^{2}D-\frac{1}{6}{H}^3)}{8\mathrm{ab}}---\left(2\right)$

Wherein, H is the actual height of the described BGA soldered ball of formula (1), and n is the soldered ball quantity of reprocessing the BGA device, and D is the diameter of soldered ball, and a is the length of square container inwall, and b is the width of square container inwall;

Step 3. places square flat container on the component pick-up pallet of reclamation work platform;

Step 4. immerses BGA device soldered ball one side in the paste soldering flux mould, and till using when picking up suction nozzle the soldered ball of BGA device being touched the bed die of paste soldering flux mould, finishes the scaling powder of BGA device and smear work.

2. shift the method for paste soldering flux in a kind of BGA device rework process as claimed in claim 1, it is characterized in that: the square container described in the step 2 comprises: housing, bed die, THICKNESS CONTROL mould and scraper plate; Housing is for having rectangular groove, and the above places the bed die with the equal-sized slab construction of groove floor; Place the THICKNESS CONTROL mould of square frame-shaped on the bed die, the thickness of THICKNESS CONTROL mould is L, and the length of THICKNESS CONTROL mould square hole is a, and the width of THICKNESS CONTROL mould square hole is b.

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