With the electronic products to high-density, high-precision development, the corresponding circuit board made the same requirements.
The most effective way to increase the density of PCBs is to reduce the number of vias and to set blind holes and fill holes.
- Blind hole definition
a: with the through-hole relative to the through-hole is the hole are drilling holes, blind hole is non-drilling through-hole.
b: (BLIND HOLE), buried hole BURIED HOLE (outer layer is not visible);
c: from the production process on the production process, the hole in the hole, Distinguish: Blind holes are drilled before crimping, and through holes are drilled after crimping.
- Production method:
a: drill belt:
(1): Select reference point: Select the through hole (ie, a hole in the first drill band) as the unit reference hole.
(2): Each blind hole drilling belt need to select a hole, marked with its relative unit reference hole coordinates.
(3): Note which drill belt which corresponds to which layers: unit sub-hole map and drill Tsui table must be marked, and before and after the name to be consistent; can not appear sub-hole diagram with abc said, and in front with 1st, 2nd Expressed the situation.
Note that when the laser hole is nested together with the inner hole, that is, the holes of the two drill holes are in the same position, the position of the laser hole is asked to move the connection. (Illustration 9430)
B: production pnl board edge process hole:
Ordinary multi-layer board: the inner layer is not drilling;
(1): rivets gh, aoi gh, et gh are eroded plate after the play (beer out)
(2): target hole (hole gh) ccd: outer layer to be painted copper, x-ray machine: direct play, and pay attention to the long side of the minimum 11inch.
All the tooling holes are drilled, pay attention to rivets gh; need to beer out, to avoid bit deviation.
(Aoi gh also for the beer out), the production of pnl board need to drill word, to distinguish between each board.
- Film modification for blind hole plate technology:
(1): Note film out positive, negative:
General principle: plate thickness greater than 8mil (not even copper) take the positive process;
Thickness less than 8mil (not even copper) take negative film process (sheet);
Line thick line gap valley when the need to consider d / f when the copper thick, rather than the end of copper thick.
Blind hole ring to do 5mil, do not need to do 7mil.
Blind holes corresponding to the inner layer of the pad are reserved.
Blind hole can not do no ring hole.
Buried orifice and ordinary double-panel practice consistent.
Blind plate, that is, one side is the outer layer:
Positive film process: need to do single-sided d / f, pay attention to not rubbing the wrong side (double-sided copper is inconsistent); d / f exposure, light copper surface covered with black tape to prevent light transmission.
Due to blind plate to do more than two times the board power, electricity, finished very easy thick plate thickness, so the figure pay attention to control the thickness of thick copper, etching, said thick copper thick plate range.
After pressing the board with x-ray machine to play multi-layer with target hole.
Negative film process: for thin plate (<12mil with copper> because it can not be produced in the map of electric pull, must be in the water Jin La production, and water Jin pull can not be sub-surface current, it can not be made by mi requirements do not play current or play Small current, such as walking process, often lead to single-sided copper thick thick, resulting in difficult etching, young line of the phenomenon, so this board to take negative film process.
- Hole, blind hole drilling in different order, the production of the deviation is inconsistent; blind hole plate is easy to produce deformation, open transverse material on the multi-layer board alignment and pipe distance control is difficult, so open only when the material or Only straight material.
- Laser drill:
LASER DRILL for a blind hole, has its own characteristics:
Pore size: 4-6 mil
Pp thickness must be <= 4.5mil, calculated according to aspect ratio <= 0.75: 1
There are three types of pp: LDPP 106 1080; FR4 106 1080; RCC.
- How to define the buried hole board need to use resin plug hole:
- H1 (CCL): H2 (PP)> = 4 thickness ratio
- HI (CCL) “32 MIL
C.2OZ and more than 2OZ laser buried plate; high thick copper, high tg board need to use resin sealing.
Such a board of the board process should pay attention to the first use of resin sealing line to avoid the line to cause greater damage.