Quality problems that can be produced by substrate and laminates

It is impossible to make any number of printed circuit boards without problems, and some of the quality reasons are attributed to the material of the copper clad laminate. When quality problems occur in the actual manufacturing process, it is often the reason that the substrate material becomes a problem. Even a technical specification for laminates that has been carefully written and implemented has not specified the test items that must be carried out to determine why laminates cause problems in the production process.


The phenomenon of signs: ink adhesion, coating adhesion is poor, some can not be etched away, and some can not solder.

Can be used to the inspection method: usually can see the water water formed in the plate surface for visual inspection or inspection using ultraviolet light irradiation, ultraviolet lamp radiation can be found in the copper foil copper foil is resin.

Possible reasons:

1. because of the very dense and smooth surface caused by the demoulding film, the surface of the uncovered copper is overly bright.

2. usually on the uncovered side of the laminates, the laminate maker does not remove the demoulding agent.

3., pinholes on copper foil cause resin to flow out and accumulate on the surface of copper foil, which usually appears on the copper foil which is thinner than the weight of 3/4 ounces, or environmental problems cause resin powder to be laminated on the surface of copper foil.


Terms of settlement:

1. it is suggested that the manufacturer of laminates use fabric like film or other demoulding material.

2. contact with the laminates manufacturer, using mechanical or chemical elimination methods.

3. contact with the laminate manufacturer to check the unqualified copper foil; take the solution to remove the resin and improve the manufacturing environment.

4. method to get rid of the laminate manufacturer. It is often recommended to use hydrochloric acid and then removed by mechanical method.



Appearance problem


The phenomenon of signs: laminate color, different colors, different surface or inner surface with a thin layer of stain, laminate on the surface of various colors.

The available examination method: visual.


Possible reasons:

1. glass cloth laminate with white linen or white spots in surface processing before or after etching.

2. after processing, there are white spots on the surface or more glass cloth.

3. after processing, especially in soldering, a thin layer of white film on the surface, it is showed that the resin is mild erosion or deposition outside.



Terms of settlement:


1. in very few cases, because of the lack of resin on the surface, the glass cloth is exposed, which is rare today. What is more often seen is small bubbles on the surface or small white holes. This is due to the reaction of the coating layer on the surface of the glass cloth and the reaction of the resin system. The surface resistivity of the plate with a lot of glass cloth is decreased when the humidity is increased. However, with small blisters or small bubble board is usually not decreased. Strictly speaking, this is just a problem of appearance, dealing with laminates manufacturers, avoiding such problems again, and determining acceptable internal standards for tiny bubbles.


2. most of the cases of glass cloth exposed after processing are due to solvent erosion, and some surface resins have been removed. Check all solvents and plating solution with laminates manufacturer, especially the time and temperature of laminates in each solution to ensure that they are suitable for the laminates. In the case of possible conditions, it is processed according to the conditions recommended by the laminate maker.



Machining problems


Phenomenon signs: the quality of punching, shearing and drilling is not consistent, the adhesion of the coating is poor or the coating is uneven in the metallized hole.

Inspection method: to check the incoming material, test all kinds of key machining operations, and carry out routine analysis after the laminates are metallized by holes.

Possible reasons:

1. the curing of materials, the content of resin, or the change of plasticizer will affect the drilling, punching and shearing quality of the material.

2. poor drilling, punching or shearing processes make the production quality poor or inconsistent.

The period of 3. punching or pre heating is too long, which sometimes affects the processing of the laminates.

The aging of 4. material is mainly phenolic, sometimes it causes the plasticizer to run off, making the material more brittle than usual.


Terms of settlement:


1. contact with the laminate maker, and establish a test that resembles the key mechanical machining performance requirements. The production die should not be used as a test, otherwise the wear and change of the production die will affect the test results. In any problem of mechanical processing performance change, only when the problem is the same batch number change at the same time, can we doubt the quality of the laminates.


2. refer to the recommendation for the manufacturing of various types of laminates.  Contact with the laminates manufacturer to identify the specific drilling speed, feed, bit and impact temperature of each level layer. Keep in mind that every manufacturer uses a mixture of different resins and substrates, and the recommendations are different.


3. carefully preheat the laminates, and be sure to find any overheating areas, such as the overheating area under the heating lamp. When the material is heated, the principle of advanced first - out should be observed.


 

(Source: internal information)

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