PCB txoj hauv kev txuas txuas ntxiv txhim kho, thiab cov txheej txheem hloov pauv tau yooj yim tuaj yeem txo cov xov hlau ntev thiab pub dawb ntau qhov chaw PCB. Cov kab hluav taws xob PCB yooj yim raug txwv los ntawm cov xov hlau ruaj khov thiab tsis muaj cov xov tooj cua tsis ncaj ncees. Tshem tawm cov kev txwv no tuaj yeem txhim kho qhov zoo ntawm cov thaiv.

Let’s start with some terminology. Peb txiav txim siab txoj kev xav tsis zoo raws li xaim hluav taws xob siv qhov kev xav tsis zoo ntawm lub kaum ntse ntse thiab radians. Nws yog ib hom xov hlau, tab sis tsis txwv rau siv tsuas yog 90 degree thiab 45 degree Angle kab ntu. Topological wiring is wire wiring that does not adhere to grids and coordinates and does not use regular or irregular grids like shape-based wiring. Cia peb txhais lub sij hawm hloov pauv tau yooj yim raws li cov xaim hluav taws xob tsis muaj cov duab ruaj khov uas ua rau lub sijhawm xaim hluav taws xob rov ua dua tshiab kom ua tiav cov kev hloov pauv hauv qab no. Tsuas yog arcs los ntawm cov teeb meem thiab lawv cov tangents ib txwm tau siv los tsim cov kab duab. (Obstacles include pins, copper foil, forbidden areas, holes and other objects) part of the circuit of two PCB models. Cov xov hlau ntsuab thiab liab khiav ntawm ntau txheej txheej ntawm PCB tus qauv. The blue circles are the perforations. The red element is highlighted. There are also some red round pins. Use only line segments and models with an Angle of 90 degrees between them. Daim duab 1B yog tus qauv PCB siv cov arcs thiab cov kev xav tsis raws cai. Wiring at any Angle may seem strange, but it does have many advantages. The way it is wired is very similar to how engineers wired it by hand half a century ago. Qhia qhov tseeb PCB tsim hauv xyoo 1972 los ntawm Asmeskas tuam txhab hu ua Digibarn kom ua tiav tes txuas. This is a PCB board based on Intel8008 computer. Qhov kev xav tsis pom lub ntsej muag pom hauv daim duab 2 yog qhov zoo sib xws. Vim li cas lawv thiaj li siv txoj hlua txoj cai tsis zoo? Vim tias hom xov hlau no muaj ntau yam zoo. Arbitrary Angle wiring has many advantages. Ua ntej, tsis txhob siv cov ces kaum ntawm kab ntu ua haujlwm txuag chaw PCB (cov duab ib txwm siv ntau qhov chaw ntau dua li tangents). Traditional automatic cablers can place only three wires between adjacent components (see left and center in Figure 3). Txawm li cas los xij, thaum txuas xov tooj ntawm ib Lub Nkoj, muaj qhov chaw txaus los tso 4 txoj xov hlau nyob rau tib txoj kev yam tsis tau ua txhaum txoj cai tshawb xyuas (DRC). Piv txwv tias peb muaj lub hom phiaj zoo thiab xav txuas cov pins nti mus rau ob lwm tus pin. Using only 90 degrees takes up a lot of space. Kev siv txoj hlua hluav taws xob tuaj yeem ua rau qhov kev ncua deb ntawm cov nti thiab lwm tus pin, thaum txo cov hneev taw. In this case, the area was reduced from 30 square centimeters to 23 square centimeters. Kev tig lub nti ntawm ib lub kaum ntse ntse tuaj yeem muab cov txiaj ntsig zoo dua. In this case, the area was reduced from 23 square centimeters to 10 square centimeters. It shows a real PCB. Arbitrary Angle wiring with rotating chip function is the only wiring method for this circuit board. Qhov no tsis yog tsuas yog kev tshawb xav, tab sis kuj yog cov tswv yim daws teeb meem (qee zaum tsuas yog kev daws teeb meem nkaus xwb). Shows an example of a simple PCB. Topology cabler cov txiaj ntsig, thaum siv cov cabler tsis siv neeg raws qhov pom zoo yog cov duab ntawm PCB tiag tiag. An automatic cabler based on optimal shape cannot do this because the components are rotated at arbitrary angles. Koj xav tau thaj chaw ntau dua, thiab yog tias koj tsis tig cov khoom sib xyaw, lub cuab yeej yuav tsum ua kom loj dua. Cov txheej txheem ua haujlwm yuav raug txhim kho zoo yam tsis muaj ntu sib dhos, uas feem ntau yog qhov chaw ntawm crosstalk. The level of crosstalk increases linearly as the length of parallel wires increases. As the spacing between parallel wires increases, crosstalk decreases quadratic. Let’s set the level of crosstalk produced by two parallel 1mm wires spaced d to e. Yog tias muaj lub kaum sab xis ntawm ntu xaim, tom qab ntawd raws li Lub Caj Npab no nce ntxiv, qib ntawm crosstalk yuav qis dua. The crosstalk does not depend on the length of the wire, but only on the Angle value: where α represents the Angle between the wire segments. Xav txog peb txoj hauv kev txuas txuas hauv qab no. On the left side of Figure 8 (90 degree layout), there is the maximum wire length and the maximum emi value due to parallel line segments. In the middle of Figure 8 (45 degree layout), the wire length and emi values are reduced. On the right-hand side (at any Angle), the wire length is shortest and there are no parallel wire segments, so the interference value is negligible. So arbitrary Angle wiring helps to reduce the total wire length and significantly reduce electromagnetic interference. You also remember the effect on signal delay (conductors should not be parallel and should not be perpendicular to the PCB fiberglass). Advantages of flexible wiring Manual and automatic movement of components does not destroy the wiring in flexible wiring. Tus cabler tau suav qhov zoo tshaj plaws ntawm cov xaim (suav nrog qhov tsim nyog tshem tawm kev nyab xeeb). Cov kab hluav taws xob hloov pauv tau tuaj yeem txo qis lub sijhawm xav tau los kho cov txheej txheem, zoo txhawb ntau yam kom rov ua tau raws cov kev txwv. Qhov no qhia txog PCB tsim uas txav los ntawm qhov thiab cov ntsiab lus ceg. Thaum lub zog txav tsis siv neeg, cov ntsiab lus hlau ceg thiab dhau los ntawm qhov raug hloov kho rau txoj haujlwm zoo. In most computer-aided design (CAD) systems, the wiring interconnection problem is reduced to the problem of sequentially finding paths between pairs of points in a maze of pads, forbidden areas, and laid wires. Thaum pom txoj hauv kev, nws tau tsau thiab dhau los ua ib feem ntawm qhov tshawb nrhiav. Qhov tsis zoo ntawm kev txuas txuas txuas yog qhov kev sib txuas yuav tshwm sim ntawm kev xaj kab. Thaum cov txheej txheem zoo tshaj plaws tseem nyob deb ntawm qhov zoo tshaj plaws, teeb meem ntawm “tau daig” tshwm sim hauv thaj chaw me me hauv zos. But no matter which wire you rewire, it’s not going to improve the quality of the wiring. This is a serious problem in all CAD systems using sequential optimization. This is where the bending elimination process is useful. Kev khoov hlau hais txog qhov tshwm sim uas xaim hauv ib lub network yuav tsum taug kev ncig ib qho khoom ntawm lwm lub network kom nkag tau mus rau ib qho khoom. Rewiring a wire will not correct this. Ib qho piv txwv ntawm dabtsi yog khoov tau qhia. A lit red wire travels around a pin in the other network, and an unlit red wire connects to this pin. Kev ua tiav cov txiaj ntsig tau tshwm sim. In the second case (on another layer), a lighted green wire is automatically rewired by changing the wiring layer (from green to red). Eliminate wire bending by automatically optimizing wire shape (approximate arcs with line segments just to show any Angle examples without arcs). (top) original design, (bottom) after eliminating bending design. Cov xov hlau khoov liab tau hais txog. Hauv tsob ntoo Steiner, txhua txoj kab yuav tsum txuas nrog ua ntu rau qhov siab (qhov kawg thiab ntxiv). Nyob rau sab saum toj ntawm txhua qhov chaw tshiab, peb ntu yuav tsum sib sau ua ke thiab tsis pub ntau tshaj peb ntu yuav tsum xaus. The Angle between the line segments that converge to the vertex shall not be less than 120 degrees. Nws tsis yog qhov nyuaj heev los tsim Steiner nrog cov peev txheej no txaus, tab sis nws tsis tas yuav tsawg. Gray Steiner trees are not optimal, but black Steiner trees are. Hauv kev tsim kev sib txuas lus siv tswv yim, ntau yam teeb meem yuav tsum tau txiav txim siab. Lawv txwv tsis pub muaj peev xwm los tsim cov ntoo tsawg kawg nkaus siv ob txoj hauv kev thiab Steiner ntoo siv txoj hauv kev. The obstacles are shown in gray and we recommend starting at any end vertex. If there is more than one adjacent terminating vertex, you should choose one that allows you to continue using the second vertex. It depends on the Angle. Lub hauv paus tseem ceeb ntawm no yog lub zog ua raws cov txheej txheem uas suav cov rog ua rau ntawm qhov chaw tshiab thiab rov txav lawv mus rau qhov sib npaug (qhov loj thiab kev taw qhia ntawm cov rog nyob ntawm cov xov hlau ntawm cov ceg lus nyob ib sab). Yog tias Lub kaum sab xis ntawm ob kab ntawm kab txuas nrog rau lub vertex (qhov kawg lossis ntxiv) tsawg dua 120 degrees, ceg ceg ntxiv tuaj yeem ntxiv, thiab tom qab ntawd cov txheej txheem txheej txheem tuaj yeem siv los ua kom zoo dua qhov chaw vertex. It’s worth noting that simply sorting all angles in descending order and adding new vertices in that order doesn’t work, and the result is worse. After adding a new node, you should check the minimum of a subnet consisting of four pins:

1. If a vertex is added to the vicinity of another newly added vertex, check for the smallest four-pin network.

2. If the four-pin network is not minimal, select a pair of “diagonal” (belonging to the quadrilateral diagonal) endpoints or virtual terminal nodes (virtual terminal nodes – wire bends).

3. The line segment that connects the endpoint (virtual endpoint) to the nearest new vertex is replaced by the line segment that connects the endpoint (virtual endpoint) to the distant new vertex.

4. Use mechanical algorithms to optimize vertex positions.

This method does not guarantee to build the smallest network, but compared with other methods, it can achieve the smallest network length without grazing. Nws kuj tseem tso cai rau thaj chaw uas txwv tsis pub sib txuas qhov kawg, thiab cov lej ntawm qhov kawg tuaj yeem yog qhov xav tau.

Flexible wiring at any Angle has some other interesting advantages. For example, if you can automatically move many objects with the help of automatic real-time wire shape recalculation, you can create parallel serpentine lines. This cabling method makes better use of space, minimizes the number of iterations, and allows for flexible use of tolerances. If there are two serpentine lines interlaced with each other, the automatic cabler will reduce the length of one or both, depending on rule priority.

Consider the wiring of BGA components. In the traditional peripheral-to-center approach, the number of channels to the periphery is reduced by 8 with each successive layer (due to a reduction in perimeter). For example, a 28x28mm component with 784 pins requires 10 layers. Qee cov khaubncaws sab nraud povtseg hauv daim duab tau dim txoj hlua. Daim duab 16 qhia txog peb lub hlis twg ntawm BGA. Nyob rau tib lub sijhawm, thaum siv “qhov chaw mus rau ib puag ncig” txoj kev txuas xov tooj, tus lej ntawm txoj hauv kev xav kom tawm mus rau ib puag ncig tsis hloov pauv ntawm txheej mus rau txheej. Qhov no yuav zoo heev txo cov txheej. Rau ib qho loj me ntawm 28x28mm, 7 txheej yog txaus. Rau cov khoom loj, nws yog yeej-yeej. Figure 17 shows a quarter of the BGA. An example of BGA wiring is shown. When using the “center to periphery” cabling approach, we can complete the cabling of all networks. Arbitrary Angle topological automatic cabler tuaj yeem ua qhov no. Traditional automatic cablers cannot route this example. Shows an example of a real PCB where the engineer reduced the number of signal layers from 6 to 4 (compared to the specification). In addition, it took engineers only half a day to complete the wiring of the PCB.