PCB Tech - Conventional PCB board inspection standards

1. What is the PCBA board inspection standard?

Let us first understand the introduction of the shortcomings of quality inspection standards

1, serious shortcomings (expressed in CR): Any shortcoming that can cause harm to the human body or the machine or endanger life safety, such as: safety inconsistency/burning/electric shock, etc.

2, the main shortcomings (indicated by MA): the shortcomings that may cause damage to the product, abnormal functions, or affect the service life of the product due to materials.

3, minor shortcomings (indicated by MI): does not affect the product function and service life, some defects in appearance and minor defects or differences in mechanical assembly.

2. Inspection conditions of PCBA board:

1, in order to prevent the contamination of parts or components, you must choose gloves or finger cots with EOS/ESD full protection function and wear electrostatic rings for operation. The light source is a white fluorescent lamp, and the light intensity must be above 100Lux, which is clearly visible within 10 seconds.

2, inspection method: place the product to be inspected about 40cm away from the eyes, 45o up and down, left and right, and inspect it visually or with a three-fold magnifying glass.

3, the inspection criterion: (Sampling according to QS9000 C=0 AQL=0.4% sampling level; if the customer has special requirements, it will be determined according to the customer's acceptance standard)

4, sampling plan: MIL-STD-105E LEVEL 2 normal single sampling

5, Judgment Standard: Serious Defects (CR) AQL 0%

6, the main disadvantage (MA) AQL 0.4%

7, minor disadvantage (MI) AQL 0.65%

Three, SMT patch workshop PCBA board inspection project standards

01, SMT parts welding spot welding

02, cold welding of the solder joints of SMT parts: Use a toothpick to lightly touch the pin of the part, if it can be moved, it is cold welding

03, SMT parts (solder joint) short circuit (tin bridge)

04, SMT parts are missing

05, SMT parts are wrong

06, the polarity of SMT parts is reversed or wrong, causing burning or explosion

07, multiple SMT parts

08, SMT parts reversal: text face down

09, SMT parts stand side by side: chip component length≤3mm, width≤1.5mm not more than five (MI)

10, SMT parts tombstone: the chip component ends upturned

11, SMT parts foot offset: side offset is less than or equal to 1/2 of the width of the weldable end

12, SMT parts floating height: the distance between the bottom of the component and the substrate <1mm

13, SMT parts feet are high: the height of the uplift is greater than the thickness of the parts feet

14, the heel of SMT parts is not flat, the heel is not tinned

15. SMT parts cannot be recognized (printing is blurred)

16, SMT parts foot or body oxidation

17, SMT parts body damage: capacitor damage (MA); resistance damage is less than 1/4 of the component width or thickness (MI); the length of any direction of IC damage is less than 1.5mm (MI), revealing the internal material (MA)

18, SMT parts use non-designated suppliers: according to BOM, ECN

19, SMT parts solder point tin tip: the height of the tin tip is greater than the height of the part body

20, SMT parts eat too little tin: the minimum solder joint height is less than the solder thickness plus 25% of the height of the solderable end or the solder thickness plus 0.5mm, the smaller of which is (MA)

21, SMT parts eat too much tin: the maximum solder joint height exceeds the pad or climbs to the top of the solderable end of the metal plating end cap for acceptance, and the solder contacts the component body (MA)

22, solder balls/dross: more than 5 solder balls per 600mm2 or solder splash (0.13mm or less) is (MA)

23, the solder joint has pinholes/blow holes: one solder joint has more than one (inclusive) as (MI)

24, crystallization phenomenon: there are white residues on the surface of the PCB board, solder terminals or around the terminals, and white crystals on the metal surface

25, the surface of the board is unclean: the uncleanness that cannot be found within 30 seconds of a long arm distance is accepted

26, poor dispensing: the glue is located in the area to be welded, reducing the width of the end to be welded by more than 50%

27, PCB copper foil peeling

28, PCB exposed copper: the circuit (gold finger) exposed copper width is greater than 0.5mm as MA)

29, PCB scratches: no substrate is seen from scratches

30, PCB burnt yellow: When the PCB is burnt and yellowed after the reflow oven or repaired, the color of the PCB is different from that of the PCB

31, PCB bending: the bending deformation in any direction exceeds 1mm (300:1) per 300mm as (MA)

32, PCB inner layer separation (bubble): the area where blistering and delamination does not exceed 25% (MI) of the distance between plated holes or between inner wires; blistering between plated holes or between inner wires (MA)

33, PCB with foreign matter: conductive (MA); non-conductive (MI)

34, PCB version error: According to BOM, ECN

35, gold finger dip tin: the tin dip position falls within 80% of the edge of the board (MA)

Four, DIP post welding workshop PCBA board inspection project standards

01, DIP part welding spot welding

02, cold welding of DIP parts: Use a toothpick to lightly touch the pin of the part, if it can be moved, it is cold welding

03, DIP part (solder joint) short circuit (tin bridge)

04, missing DIP parts:

05, the pin length of DIP parts: Φ≤0.8mm-the pin length is less than or equal to 1.5mm Φ＞0.8mm-the pin length is less than or equal to 2.0mm, except for special trimming requirements

06, DIP parts are wrong:

07, the polarity of DIP parts is reversed or wrong, causing burning or explosion

08, DIP part pin deformation: The bending of the pin exceeds 50% of the thickness of the pin

09, DIP parts floating high or high warping: refer to IPC-A-610E, according to the special circumstances of the assembly

10, DIP part solder point tin tip: the height of the tin tip is greater than 1.5mm

11, DIP parts cannot be identified: (printing is blurred)

12, DIP part foot or body oxidation

13, DIP part body is damaged: The surface of the component is damaged, but the metal material inside the component is not exposed

14, DIP parts use non-designated suppliers: According to BOM, ECN

15, PTH hole vertical filling and peripheral wetting: at least 75% vertical filling, pins and hole walls are wetted at least 270o

16, solder balls/dross: more than 5 solder balls per 600mm2 or solder splash (0.13mm or less) is (MA)

17, the solder joint has pinholes/blow holes: a solder joint has three (including) or more as (MI)

18, crystallization phenomenon: There are white residues on the surface of the PCB board, solder terminals or around the terminals, and white crystals on the metal surface

19, the surface of the board is unclean: the uncleanness that cannot be found within 30 seconds of a long arm distance is accepted

20, poor glue dispensing: The glue is located in the area to be welded, reducing the width of the end to be welded by more than 50%

21,PCB copper foil warped skin:

22, PCB exposed copper: The width of the exposed copper of the circuit (gold finger) is greater than 0.5mm (MA)

23, PCB scratch: No substrate is seen from scratch

24, PCB scorch: When the PCB is burnt and yellowed after the reflow oven or repaired, the color of the PCB is different from that of the PCB

25, PCB bending: the deformation of bending in any direction exceeds 1mm (300:1) per 300mm as (MA)

26, PCB inner layer separation (bubble): the area where blistering and delamination does not exceed 25% (MI) of the distance between plated holes or between inner wires; blistering between plated holes or between inner wires (MA)

27, PCB with foreign matter: conductive (MA); non-conductive (MI)

28, PCB version error: according to BOM, ECN

29, gold finger dip tin: the tin dip position falls within 80% of the board edge (MA)