PCB Circuit Board Testing, Inspection and Specification (1)

writer: G June 17, 2019

1. Acceptability, acceptance:

The former refers to the various operating conditions and written guidelines that should be observed when inspecting semi-finished or finished products.

The latter refers to the process of performing an acceptance test, such as Acceptance Test.

2. Acceptable Quality Level (AQL):

When the inspection is inspected, it is considered to meet the "non-performing rate upper limit" of the engineering requirements, or the upper limit of the number of defects. AQL is not designed to protect a particular batch, but is a guarantee for continuous batch quality.

3. Air Inclusion Bubble:

When the liquid material coating process is carried out on the board, air bubbles often remain in the paint, such as bubbles in the film resin, or bubbles in the green paint film. Such inclusions are not good for electrical or physical properties of the board.

4. AOI: Automatic Optical Inspection

Using ordinary light or laser light in conjunction with a computer program to visually inspect the appearance of the board surface to replace the optical equipment for manual visual inspection.

5. AQL: Acceptable Quality Level,

In the quality inspection items of a large number of products, a small amount of inspection is carried out, and then the quality control technology of the whole batch of movements is determined.

6. ATE: Automatic Testing Equipment

In order to ensure the smoothness of the circuit system of the completed circuit board, it is necessary to electrically measure the board with a specific contact pin on a general-purpose electric measuring machine with a high voltage (such as 250 V) multi-measurement point.

7. Blister:

In the circuit manufacturing process, the delamination of the partial or partial plates or the partial copper foil floating often occurs, which is called Blister. In the general electroplating process, the substrate is often unclean, and the plating is foamed, especially in the case of silver-plated objects, which are most likely to be foamed in post-baking.

8. Bow, Bowing Plate Bend:

When the board loses its flatness, it is placed on a flat surface with its concave surface facing down. If it cannot keep the corner of the board on a flat surface, it is called a plate bend or a warp (Warp or Warpage), if only three points fall on the plane, it is called Twist. However, when the twisting situation is usually not too obvious, it is commonly known as Warpage.

9. Break-Out:

It means that the drilled hole breaks out from the circle of the pad to form a broken ring; that is, the hole position is not aligned with the pad to be drilled, so that the two centers do not fall. At one point. Of course, both drilling and image transfer may be the cause of inaccuracy or breakage. However, there are thousands of holes on the board. It is impossible for each to be aligned. As long as no "breaking" occurs, and the narrowest hole formed is not below the specification (generally 2 mil or more), Acceptance.

10. Bridging Bridge, Bridge:

Refers to an improper short circuit between two lines that should be isolated from each other.

11. Certificate:

When a specific "personnel training" or "quality test" is completed and meets a certain professional standard, the document, which is certified in writing, is called a Certificate.

12. Check List:

Broadly refers to items that should be checked one by one for safety reasons before various operations. Narrow sense refers to the various items that the customer visits the site but understands the quality and examines them one by one.

13. Continuity:

Refers to the circuit in the circuit (Circuits) the flow of current is smooth. In addition, Continuity Testing refers to the test of the energization of each line, that is, two points are found at each end of each line, and the elastic probe is used for pressing contact with each other (the whole board is implemented by a needle bed), and then Apply a specified voltage (usually twice the utility voltage) and perform a "connectivity test", also known as Open/Short Testing.

14. Coupon, Test Coupon:

The board needs to know the quality of its details, especially the through-hole structure of the multilayer board. It cannot be visually inspected and tested by electrical inspection. Further microsection inspection of its structure is required. Therefore, an additional "through hole and line" pattern should be placed at one or more sides of the board as an anatomical slice matching sample (Strformal Coupon) for monitoring the structural integrity of the sheet. If the quality is extremely strict, the board will not be shipped when the sample fails. Note that this kind of edge cutting can be used not only as a quality inspection item for shipment, but also as a countermeasure research for problems and a monitoring tool for quality improvement. In addition to the micro-slice samples, a special Coupon that checks the "characteristic impedance" is sometimes added to the edge of the board to check whether the "impedance value" of each multi-layer board is still controlled within the specified range.

15. Crazing White Spot:

It refers to the shortcoming of the appearance of the substrate, which may be due to the split between the local fiberglass cloth and the epoxy resin, or the yarn bundle of the cloth itself, and the white area can be seen as Crazing. Smaller and only appearing on the weaving point, called "Measling". In addition, when the outer surface of the panel is coated with a Conformal Coating, the crack is also called Crazing. Usually, general-purpose porcelain, or ceramic tiles, after aging for a long period of time, also have irregular cracks on the surface due to the release of force, also known as Crazing.

16. Cross Cut Test:

It is a destructive test for the adhesion of the surface film. It was slightly modified according to the tape tearing method of ASTM D3359, and was tested for adhesion of various wet and dry films on the board surface. The multi-blade cutting knife is cut vertically and horizontally on the surface of the film, cut into many small squares and then pressed with a tape and then torn hard. The square incisions are smooth and all are not torn off for 5 minutes. The incisions are both broken and torn. The squares are only 1 point between 35 and 65%, and worse, 0 points. Even if it is done several times for comparison, the total score is the number of scores of the film adhesion.

17. Dendritic Growth:

It refers to the influence of long-term voltage (bias) between the two conductors on the surface of the circuit board, and the dendritic growth of metal ions. Finally, the surface of the insulated sheet is overlapped and leakage occurs. The case of short circuit is called "dendritic growth". It is called Dendritic Migration or Dentrices when it continues to penetrate into the insulation.

18. Deviation:

It means that the measured data is not good, and the difference between it and the normal acceptance specification is called Deviation.

19. Eddy Current:

It is a working principle and method for measuring various film thicknesses. It can measure the thickness of non-conductor film of non-magnetic metal substrate (such as copper layer resin layer or green paint thickness) when it is wound around a core probe. With a coil, a high-frequency oscillating alternating current (100 kHz to 6 MHz) is applied to generate a magnetic field. When the probe touches the surface to be tested, the bottom metal layer (such as copper) is induced to generate "eddy current", and the eddy current signal is detected by the probe. Where the surface non-conductor film is thicker, the greater the effect of blocking the eddy current, the weaker the signal that the probe can receive. On the contrary, the thinner the film, the stronger the signal that the probe can receive. Therefore, this principle can be used to measure the thickness of the non-conductor film. Generally, the thickness of the anodized film on the surface of the aluminum material, the thickness of the substrate on the copper foil substrate, and any similar combination can be measured. In general, eddy currents are also generated in the circuit system, but they are ineffective currents that can only be wasted by heating.

20. Dish Down:

It refers to a partial area on the copper conductor line of the circuit board surface, which is improperly rounded by the pressing when it is pressed, and it is unfortunately left on the line after etching, which is called "disc trap". In a high-speed transmission line, such a local depression will cause a sudden change in the impedance value, which is unfavorable to the overall function, so it should be avoided as much as possible.

21. Edge-Dip Solderability Test:

It is a simple test method for the solderability of a circuit board (or other component feet). The sample of a specific circuit can be clamped by a test machine or a hand operation after being fluxed, and the molten tin is slowly pressed vertically. In the pool, after 1 to 2 seconds, take it out at a constant speed. After washing, observe the tint property of the surface conductor or through hole of the board.

22. Eyelet Riveting Eyes:

It is a hollow rivet made of bronze or brass. When a certain hole is broken on the circuit board, the "Eyelet" can be added to maintain the conductive function and to accept the soldered part. However, due to the strict requirements on the quality of circuit boards in the industry, the opportunities for adding Eyelet are becoming less and less.

23. Failure:

Refers to a situation where a product or component cannot achieve normal function.

24. Fault:

A fault is called when there are some substandard quality defects on the component or product, or if the normal operation cannot be performed due to bad factors.

25. Fiber Exposure:

It refers to the surface of the substrate that may be lost by the external mechanical friction, chemical reaction, etc., may lose the resin layer covered by its appearance (Butter Coat), the fiberglass cloth exposing the substrate, called "Fiber Exposure", also known as "Weave Exposure is revealed", and a glass fiber bundle with a miscut on the wall of the hole is called a glass protrusion.

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