CN102410829A - Method for judging warping of BGA device or PCB - Google Patents

Abstract

The invention provides A method for judging the warping of a BGA device or a PCB comprises the following steps: A. placing the circuit board sample provided with the BGA device in an X-ray to measure the spherical diameter distribution of a welding spot between the BGA device and a PCB; B. measuring the height distribution of welding points around the BGA device on the circuit board sample by using a stereo microscope; C. and judging whether the BGA device or the PCB warps on the circuit board sample according to the change trend of the height distribution and the spherical diameter distribution of the welding points between the BGA device and the PCB. The method does not damage the sample and is nondestructive detection; the method has simple operation steps, high detection speed and high efficiency; the method can quickly and accurately judge the warping degree of the BGA device or the PCB, and provides effective information for subsequent analysis work.

Description

The determination methods of a kind of BGA device or PCB warpage

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Technical field

the present invention relates to the determination methods of a kind of BGA device or PCB warpage.

 

Background technology

are the conventional surface-mounted technology relatively, when a linear connected mode in periphery is transformed into a two-dimensional array, under identical size, bigger pin-pitch, can realize more POI.To be that this notion is modal carry into execution a plan BGA.Yet all array package all have a common problem: non-package edge solder joint is sightless, and can not be through visual examination to confirm its quality or to assert defective.

several years ago, the BGA device usually only number of pins greater than 200 application-specific integrated circuit ASIC on, at that time, it is rarely found using more than one BGA device on the plate.These 2 years, because the reduction of cost and the improvement of heat dispersion, the application of BGA device and CSP that is less than 100 pins was very general.Certainly, the BGA device greater than 100 pins is most typical.

It is the same with QFP common that BGA device has become.Most of plank all can be assembled one at least, and it also is very common that every block of plate has 10 to 20 BGA devices.Today, complicated PCB has 25%～50% solder joint to belong to the BGA device.Even have a good characteristic and controlled packaging technology, because the method for any visual examination has all lost effect, weld defects will occur on the BGA device certainly.

are attached on the PCB when crossing Reflow Soldering at the BGA device; In order to make the tin ball total reflux on scolder and the BGA device form reliable solder joint, assembly can place 60～90s under 217～260 ℃ the high temperature, and the substrate of BGA device generally is the BT material; PCB generally is the FR-4 material; So reflux temperature is higher than the glass transition temperature of two kinds of materials, add the cohesion of scolder, the warpage of base plate for packaging and pcb board just possibly appear.Warpage possibly perhaps caused from accumulating in the release of intralamellar part stress when welding in the PCB manufacture process by inhomogeneous or postwelding cooling fast.For the BGA encapsulation,, in heating or cooling procedure, also possibly cause warpage if the design of the substrate pothole of placement chip is asymmetric.Because solder joint does not solidify at one time, the warpage that originally after cooling, can disappear usually may be formalized.

warpage is normally passed to gradual change whole BGA device to the influence of diameter.Space between BGA device and plank is not have unexpected variation or the generation of discontinuous phenomenon.The warpage of BGA device is used microsection and fractographic methods analyst usually at present; This methods analyst time is long; Complex procedures; Cost is high, and therefore, judging the problem whether BGA device or PCB warpage take place how fast, efficiently, accurately becomes failure analysis field problem demanding prompt solution.

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Summary of the invention

In order to solve existing BGA device or PCB warping Analysis method time length, complex procedures, problem that cost is high, the present invention proposes following technical scheme:

The determination methods of a kind of BGA device or PCB warpage, this method may further comprise the steps:

The sphere diameter that A, the circuit board sample that the BGA device will be installed place X-ray to measure solder joint between BGA device and the pcb board distributes;

The height profile of solder joint around the BGA device on B, the use stereo microscope metering circuit plate sample;

C, judge this circuit board sample according to the variation tendency that solder joint height between BGA device and the pcb board distributes and the solder joint sphere diameter distributes whether BGA device warpage or PCB warpage take place.

The beneficial effect that the present invention brings is:

1, the inventive method does not produce sample and destroys, for non-destructive detects;

2, the inventive method operation steps is simple, and detection speed is fast, and efficient is high;

3, the inventive method can quick and precisely be judged the degree of BGA device or PCB warpage, for follow-up analytical work provides effective information.

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Embodiment

Set forth in the face of preferred embodiment of the present invention down in detail , thereby so that advantage of the present invention and characteristic can be easier to it will be appreciated by those skilled in the art that protection scope of the present invention is made more explicit defining.

Present embodiment carries out warping Analysis to the BGA device in certain circuit board, and it is following specifically to detect step:

The sphere diameter that A, the circuit board sample that the BGA device will be installed place X-ray to measure solder joint between BGA device and the pcb board distributes, and the sphere diameter of measuring the BGA device distributes to pass through and diminishes successively;

The height profile of solder joint around the BGA device increases according to sphere diameter direction from big to small successively on B, the use stereo microscope metering circuit plate sample;

C, according to solder joint height between BGA device and the pcb board distributes and the solder joint sphere diameter distributes variation tendency; And therefore the error of the highs and lows error of solder joint height and solder joint sphere diameter biggest ball footpath and minimum sphere diameter is judged this circuit board sample the BGA warpage is taken place all above 15%.

the above; Be merely embodiment of the present invention; But protection scope of the present invention is not limited thereto; Any those of ordinary skill in the art are in the technical scope that the present invention disclosed, and variation or the replacement that can expect without creative work all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain that claims were limited.

Claims (1)

1. the determination methods of BGA device or PCB warpage, it is characterized in that: this method may further comprise the steps:

The sphere diameter that A, the circuit board sample that the BGA device will be installed place X-ray to measure solder joint between BGA device and the pcb board distributes;

The height profile of solder joint around the BGA device on B, the use stereo microscope metering circuit plate sample;

C, judge this circuit board sample according to the variation tendency that solder joint height between BGA device and the pcb board distributes and the solder joint sphere diameter distributes whether BGA device warpage or PCB warpage take place.